The difference between the two sets of APIs is now miniscule.
This allows tlb_flush, tlb_flush_all_cpus, and tlb_flush_all_cpus_synced
to be merged with their corresponding by_mmuidx functions as well. For
accounting, consider mmu_idx_bitmask = ALL_MMUIDX_BITS to be a full flush.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The rest of the tlb victim cache is per-tlb,
the next use index should be as well.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The set of large pages in the kernel is probably not the same
as the set of large pages in the application. Forcing one
range to cover both will flush more often than necessary.
This allows tlb_flush_page_async_work to flush just the one
mmu_idx implicated, which in turn allows us to remove
tlb_check_page_and_flush_by_mmuidx_async_work.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Protect it with the tlb_lock instead of using atomics.
The move puts it in or near the same cacheline as the lock;
using the lock means we don't need a second atomic operation
in order to perform the update. Which makes it cheap to also
update pending_flush in tlb_flush_by_mmuidx_async_work.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The bugs this was working around were fixed with commits
022d6378c7 target/unicore32: remove tlb_flush from uc32_init_fn
6e11beecfd target/alpha: remove tlb_flush from alpha_cpu_initfn
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This is the first of several moves to reduce the size of the
CPU_COMMON_TLB macro and improve some locality of refernce.
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
GCC7+ will no longer advertise support for 16-byte __atomic operations
if only cmpxchg is supported, as for x86_64. Fortunately, x86_64 still
has support for __sync_compare_and_swap_16 and we can make use of that.
AArch64 does not have, nor ever has had such support, so open-code it.
Reviewed-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Isolate the computation of an index from an address into a
helper before we change that function.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
[ cota: convert tlb_vaddr_to_host; use atomic_read on addr_write ]
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181009175129.17888-2-cota@braap.org>
Currently we rely on atomic operations for cross-CPU invalidations.
There are two cases that these atomics miss: cross-CPU invalidations
can race with either (1) vCPU threads flushing their TLB, which
happens via memset, or (2) vCPUs calling tlb_reset_dirty on their TLB,
which updates .addr_write with a regular store. This results in
undefined behaviour, since we're mixing regular and atomic ops
on concurrent accesses.
Fix it by using tlb_lock, a per-vCPU lock. All updaters of tlb_table
and the corresponding victim cache now hold the lock.
The readers that do not hold tlb_lock must use atomic reads when
reading .addr_write, since this field can be updated by other threads;
the conversion to atomic reads is done in the next patch.
Note that an alternative fix would be to expand the use of atomic ops.
However, in the case of TLB flushes this would have a huge performance
impact, since (1) TLB flushes can happen very frequently and (2) we
currently use a full memory barrier to flush each TLB entry, and a TLB
has many entries. Instead, acquiring the lock is barely slower than a
full memory barrier since it is uncontended, and with a single lock
acquisition we can flush the entire TLB.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181009174557.16125-6-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181009174557.16125-5-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Paves the way for the addition of a per-TLB lock.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181009174557.16125-4-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Consistently access u16.high with atomics to avoid
undefined behaviour in MTTCG.
Note that icount_decr.u16.low is only used in icount mode,
so regular accesses to it are OK.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <20181010144853.13005-2-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Rather than test NOCHAIN before linking, do not emit the
goto_tb opcode at all. We already do this for goto_ptr.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The global cpu_single_env variable has been removed more than 5 years
ago, so apparently nobody used this dead debug code in that timeframe
anymore. Thus let's remove it completely now.
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1537204134-15905-1-git-send-email-thuth@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
QEMU cannot pass through the breakpoints when 'si' command is used
in remote gdb. This patch disables inserting the breakpoints
when we are already single stepping though the gdb remote protocol.
This patch also fixes icount calculation for the blocks that include
breakpoints - instruction with breakpoint is not executed and shouldn't
be used in icount calculation.
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-Id: <20180912081910.3228.8523.stgit@pasha-VirtualBox>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Accessing the HT from an iterator results almost always
in a deadlock. Given that only one qht-internal function
uses this argument, drop it from the interface.
Suggested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
We set up TLB entries in tlb_set_page_with_attrs(), where we have
some logic for determining whether the TLB entry is considered
to be RAM-backed, and thus has a valid addend field. When we
look at the TLB entry in get_page_addr_code(), we use different
logic for determining whether to treat the page as RAM-backed
and use the addend field. This is confusing, and in fact buggy,
because the code in tlb_set_page_with_attrs() correctly decides
that rom_device memory regions not in romd mode are not RAM-backed,
but the code in get_page_addr_code() thinks they are RAM-backed.
This typically results in "Bad ram pointer" assertion if the
guest tries to execute from such a memory region.
Fix this by making get_page_addr_code() just look at the
TLB_MMIO bit in the code_address field of the TLB, which
tlb_set_page_with_attrs() sets if and only if the addend
field is not valid for code execution.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180713150945.12348-1-peter.maydell@linaro.org
Now that all the callers can handle get_page_addr_code() returning -1,
remove all the code which tries to handle execution from MMIO regions
or small-MMU-region RAM areas. This will mean that we can correctly
execute from these areas, rather than ending up either aborting QEMU
or delivering an incorrect guest exception.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Cédric Le Goater <clg@kaod.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180710160013.26559-6-peter.maydell@linaro.org
If get_page_addr_code() returns -1, this indicates that there is no RAM
page we can read a full TB from. Instead we must create a TB which
contains a single instruction and which we do not cache, so it is
executed only once.
Since this means we can now have TBs which are not in any page list,
we also need to make tb_phys_invalidate() handle them (by not trying
to remove them from a nonexistent page list).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Tested-by: Cédric Le Goater <clg@kaod.org>
Message-id: 20180710160013.26559-5-peter.maydell@linaro.org
When we support execution from non-RAM MMIO regions, get_page_addr_code()
will return -1 to indicate that there is no RAM at the requested address.
Handle this in tb_check_watchpoint() -- if the exception happened for a
PC which doesn't correspond to RAM then there is no need to invalidate
any TBs, because the one-instruction TB will not have been cached.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Cédric Le Goater <clg@kaod.org>
Message-id: 20180710160013.26559-4-peter.maydell@linaro.org
When we support execution from non-RAM MMIO regions, get_page_addr_code()
will return -1 to indicate that there is no RAM at the requested address.
Handle this in the cpu-exec TB hashtable lookup code, treating it as
"no match found".
Note that the call to get_page_addr_code() in tb_lookup_cmp() needs
no changes -- a return of -1 will already correctly result in the
function returning false.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Emilio G. Cota <cota@braap.org>
Tested-by: Cédric Le Goater <clg@kaod.org>
Message-id: 20180710160013.26559-3-peter.maydell@linaro.org
The io_readx() function needs to know whether the load it is
doing is an MMU_DATA_LOAD or an MMU_INST_FETCH, so that it
can pass the right value to the cpu_transaction_failed()
function. Plumb this information through from the softmmu
code.
This is currently not often going to give the wrong answer,
because usually instruction fetches go via get_page_addr_code().
However once we switch over to handling execution from non-RAM by
creating single-insn TBs, the path for an insn fetch to generate
a bus error will be through cpu_ld*_code() and io_readx(),
so without this change we will generate a d-side fault when we
should generate an i-side fault.
We also have to pass the access type via a CPU struct global
down to unassigned_mem_read(), for the benefit of the targets
which still use the cpu_unassigned_access() hook (m68k, mips,
sparc, xtensa).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Cédric Le Goater <clg@kaod.org>
Message-id: 20180710160013.26559-2-peter.maydell@linaro.org
In commit 4b1a3e1e34 we added a check for whether the TLB entry
we had following a tlb_fill had the INVALID bit set. This could
happen in some circumstances because a stale or wrong TLB entry was
pulled out of the victim cache. However, after commit
68fea03855 (which prevents stale entries being in the victim
cache) and the previous commit (which ensures we don't incorrectly
hit in the victim cache)) this should never be possible.
Drop the check on TLB_INVALID_MASK from the "is this a TLB_RECHECK?"
condition, and instead assert that the tlb fill procedure has given
us a valid TLB entry (or longjumped out with a guest exception).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180713141636.18665-3-peter.maydell@linaro.org
In get_page_addr_code(), we were incorrectly looking in the victim
TLB for an entry which matched the target address for reads, not
for code accesses. This meant that we could hit on a victim TLB
entry that indicated that the address was readable but not
executable, and incorrectly bypass the call to tlb_fill() which
should generate the guest MMU exception. Fix this bug.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180713141636.18665-2-peter.maydell@linaro.org
The typo was found by codespell.
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Message-Id: <20180712194454.26765-1-sw@weilnetz.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This fixes a record-replay regression introduced by 95590e2
("translate-all: discard TB when tb_link_page returns an existing
matching TB", 2018-06-15). The problem is that code using CF_NOCACHE
assumes that the TB returned from tb_gen_code is always a
newly-generated one. This assumption, however, was broken in
the aforementioned commit.
Fix it by honouring CF_NOCACHE, so that tb_gen_code always
returns a newly-generated TB when CF_NOCACHE is passed to it.
Do this by avoiding the TB hash table if CF_NOCACHE is set.
Reported-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Tested-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 1530806837-5416-1-git-send-email-cota@braap.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
When installing a TLB entry, remove any cached version of the
same page in the VTLB. If the existing TLB entry matches, do
not copy into the VTLB, but overwrite it.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
In get_page_addr_code() when we check whether the TLB entry
is marked as TLB_RECHECK, we should not go down that code
path if the TLB entry is not valid at all (ie the TLB_INVALID
bit is set).
Tested-by: Laurent Vivier <laurent@vivier.eu>
Reported-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20180629161731.16239-1-peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
In commit 71b9a45330 we changed the condition we use
to determine whether we need to refill the TLB in
get_page_addr_code() to
if (unlikely(env->tlb_table[mmu_idx][index].addr_code !=
(addr & (TARGET_PAGE_MASK | TLB_INVALID_MASK)))) {
This isn't the right check (it will falsely fail if the
input addr happens to have the low bit corresponding to
TLB_INVALID_MASK set, for instance). Replace it with a
use of the new tlb_hit() function, which is the correct test.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20180629162122.19376-3-peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The condition to check whether an address has hit against a particular
TLB entry is not completely trivial. We do this in various places, and
in fact in one place (get_page_addr_code()) we have got the condition
wrong. Abstract it out into new tlb_hit() and tlb_hit_page() inline
functions (one for a known-page-aligned address and one for an
arbitrary address), and use them in all the places where we had the
condition correct.
This is a no-behaviour-change patch; we leave fixing the buggy
code in get_page_addr_code() to a subsequent patch.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20180629162122.19376-2-peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Commit 0b5c91f ("translate-all: use per-page locking in !user-mode",
2018-06-15) introduced per-page locking. It assumed that the physical
pages corresponding to a TB (at most two pages) are always distinct,
which is wrong. For instance, an xtensa test provided by Max Filippov
is broken by the commit, since the test maps two virtual pages
to the same physical page:
virt1: 7fff, virt2: 8000
phys1 6000fff, phys2 6000000
Fix it by removing the assumption from page_lock_pair.
If the two physical page addresses are equal, we only lock
the PageDesc once. Note that the two callers of page_lock_pair,
namely page_unlock_tb and tb_link_page, are also updated so that
we do not try to unlock the same PageDesc twice.
Fixes: 0b5c91f74f
Reported-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <1529944302-14186-1-git-send-email-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
When guest CPU PM is enabled, and with -cpu host, expose the host CPU
MWAIT leaf in the CPUID so guest can make good PM decisions.
Note: the result is 100% CPU utilization reported by host as host
no longer knows that the CPU is halted.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20180622192148.178309-3-mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Place them in exec.c, exec-all.h and ram_addr.h. This removes
knowledge of translate-all.h (which is an internal header) from
several files outside accel/tcg and removes knowledge of
AddressSpace from translate-all.c (as it only operates on ram_addr_t).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Determining the size of a field is useful when you don't have a struct
variable handy. Open-coding this is ugly.
This patch adds the sizeof_field() macro, which is similar to
typeof_field(). Existing instances are updated to use the macro.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20180614164431.29305-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
We do not trace guest atomic accesses. Fix it.
Tested with a modified atomic_add-bench so that it executes
a deterministic number of instructions, i.e. fixed seeding,
no threading and fixed number of loop iterations instead
of running for a certain time.
Before:
- With parallel_cpus = false (no clone syscall so it is never set to true):
220070 memory accesses
- With parallel_cpus = true (hard-coded):
212105 memory accesses <-- we're not tracing the atomics!
After:
220070 memory accesses regardless of parallel_cpus.
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-id: 1527028012-21888-6-git-send-email-cota@braap.org
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Add support for MMU protection regions that are smaller than
TARGET_PAGE_SIZE. We do this by marking the TLB entry for those
pages with a flag TLB_RECHECK. This flag causes us to always
take the slow-path for accesses. In the slow path we can then
special case them to always call tlb_fill() again, so we have
the correct information for the exact address being accessed.
This change allows us to handle reading and writing from small
regions; we cannot deal with execution from the small region.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180620130619.11362-2-peter.maydell@linaro.org
Use mmap_lock in user-mode to protect TCG state and the page descriptors.
In !user-mode, each vCPU has its own TCG state, so no locks needed.
Per-page locks are used to protect the page descriptors.
Per-TB locks are used in both modes to protect TB jumps.
Some notes:
- tb_lock is removed from notdirty_mem_write by passing a
locked page_collection to tb_invalidate_phys_page_fast.
- tcg_tb_lookup/remove/insert/etc have their own internal lock(s),
so there is no need to further serialize access to them.
- do_tb_flush is run in a safe async context, meaning no other
vCPU threads are running. Therefore acquiring mmap_lock there
is just to please tools such as thread sanitizer.
- Not visible in the diff, but tb_invalidate_phys_page already
has an assert_memory_lock.
- cpu_io_recompile is !user-only, so no mmap_lock there.
- Added mmap_unlock()'s before all siglongjmp's that could
be called in user-mode while mmap_lock is held.
+ Added an assert for !have_mmap_lock() after returning from
the longjmp in cpu_exec, just like we do in cpu_exec_step_atomic.
Performance numbers before/after:
Host: AMD Opteron(tm) Processor 6376
ubuntu 17.04 ppc64 bootup+shutdown time
700 +-+--+----+------+------------+-----------+------------*--+-+
| + + + + + *B |
| before ***B*** ** * |
|tb lock removal ###D### *** |
600 +-+ *** +-+
| ** # |
| *B* #D |
| *** * ## |
500 +-+ *** ### +-+
| * *** ### |
| *B* # ## |
| ** * #D# |
400 +-+ ** ## +-+
| ** ### |
| ** ## |
| ** # ## |
300 +-+ * B* #D# +-+
| B *** ### |
| * ** #### |
| * *** ### |
200 +-+ B *B #D# +-+
| #B* * ## # |
| #* ## |
| + D##D# + + + + |
100 +-+--+----+------+------------+-----------+------------+--+-+
1 8 16 Guest CPUs 48 64
png: https://imgur.com/HwmBHXe
debian jessie aarch64 bootup+shutdown time
90 +-+--+-----+-----+------------+------------+------------+--+-+
| + + + + + + |
| before ***B*** B |
80 +tb lock removal ###D### **D +-+
| **### |
| **## |
70 +-+ ** # +-+
| ** ## |
| ** # |
60 +-+ *B ## +-+
| ** ## |
| *** #D |
50 +-+ *** ## +-+
| * ** ### |
| **B* ### |
40 +-+ **** # ## +-+
| **** #D# |
| ***B** ### |
30 +-+ B***B** #### +-+
| B * * # ### |
| B ###D# |
20 +-+ D ##D## +-+
| D# |
| + + + + + + |
10 +-+--+-----+-----+------------+------------+------------+--+-+
1 8 16 Guest CPUs 48 64
png: https://imgur.com/iGpGFtv
The gains are high for 4-8 CPUs. Beyond that point, however, unrelated
lock contention significantly hurts scalability.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
tb_lock was needed when the function did retranslation. However,
since fca8a500d5 ("tcg: Save insn data and use it in
cpu_restore_state_from_tb") we don't do retranslation.
Get rid of the comment.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The acquisition of tb_lock was added when the async tlb_flush
was introduced in e3b9ca810 ("cputlb: introduce tlb_flush_* async work.")
tb_lock was there to allow us to do memset() on the tb_jmp_cache's.
However, since f3ced3c592 ("tcg: consistently access cpu->tb_jmp_cache
atomically") all accesses to tb_jmp_cache are atomic, so tb_lock
is not needed here. Get rid of it.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This applies to both user-mode and !user-mode emulation.
Instead of relying on a global lock, protect the list of incoming
jumps with tb->jmp_lock. This lock also protects tb->cflags,
so update all tb->cflags readers outside tb->jmp_lock to use
atomic reads via tb_cflags().
In order to find the destination TB (and therefore its jmp_lock)
from the origin TB, we introduce tb->jmp_dest[].
I considered not using a linked list of jumps, which simplifies
code and makes the struct smaller. However, it unnecessarily increases
memory usage, which results in a performance decrease. See for
instance these numbers booting+shutting down debian-arm:
Time (s) Rel. err (%) Abs. err (s) Rel. slowdown (%)
------------------------------------------------------------------------------
before 20.88 0.74 0.154512 0.
after 20.81 0.38 0.079078 -0.33524904
GTree 21.02 0.28 0.058856 0.67049808
GHashTable + xxhash 21.63 1.08 0.233604 3.5919540
Using a hash table or a binary tree to keep track of the jumps
doesn't really pay off, not only due to the increased memory usage,
but also because most TBs have only 0 or 1 jumps to them. The maximum
number of jumps when booting debian-arm that I measured is 35, but
as we can see in the histogram below a TB with that many incoming jumps
is extremely rare; the average TB has 0.80 incoming jumps.
n_jumps: 379208; avg jumps/tb: 0.801099
dist: [0.0,1.0)|▄█▁▁▁▁▁▁▁▁▁▁▁ ▁▁▁▁▁▁ ▁▁▁ ▁▁▁ ▁|[34.0,35.0]
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Use the recently-gained QHT feature of returning the matching TB if it
already exists. This allows us to get rid of the lookup we perform
right after acquiring tb_lock.
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The appended adds assertions to make sure we do not longjmp with page
locks held. Note that user-mode has nothing to check, since page_locks
are !user-mode only.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This is only compiled under CONFIG_DEBUG_TCG to avoid
bloating the binary.
In user-mode, assert_page_locked is equivalent to assert_mmap_lock.
Note: There are some tb_lock assertions left that will be
removed by later patches.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Suggested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Groundwork for supporting parallel TCG generation.
Instead of using a global lock (tb_lock) to protect changes
to pages, use fine-grained, per-page locks in !user-mode.
User-mode stays with mmap_lock.
Sometimes changes need to happen atomically on more than one
page (e.g. when a TB that spans across two pages is
added/invalidated, or when a range of pages is invalidated).
We therefore introduce struct page_collection, which helps
us keep track of a set of pages that have been locked in
the appropriate locking order (i.e. by ascending page index).
This commit first introduces the structs and the function helpers,
to then convert the calling code to use per-page locking. Note
that tb_lock is not removed yet.
While at it, rename tb_alloc_page to tb_page_add, which pairs with
tb_page_remove.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This greatly simplifies next commit's diff.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
So that we pass a same-page range to tb_invalidate_phys_page_range,
instead of always passing an end address that could be on a different
page.
As discussed with Peter Maydell on the list [1], tb_invalidate_phys_page_range
doesn't actually do much with 'end', which explains why we have never
hit a bug despite going against what the comment on top of
tb_invalidate_phys_page_range requires:
> * Invalidate all TBs which intersect with the target physical address range
> * [start;end[. NOTE: start and end must refer to the *same* physical page.
The appended honours the comment, which avoids confusion.
While at it, rework the loop into a for loop, which is less error prone
(e.g. "continue" won't result in an infinite loop).
[1] https://lists.gnu.org/archive/html/qemu-devel/2017-07/msg09165.html
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Groundwork for supporting parallel TCG generation.
Move the hole to the end of the struct, so that a u32
field can be added there without bloating the struct.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Groundwork for supporting parallel TCG generation.
We never remove entries from the radix tree, so we can use cmpxchg
to implement lockless insertions.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit does several things, but to avoid churn I merged them all
into the same commit. To wit:
- Use uintptr_t instead of TranslationBlock * for the list of TBs in a page.
Just like we did in (c37e6d7e "tcg: Use uintptr_t type for
jmp_list_{next|first} fields of TB"), the rationale is the same: these
are tagged pointers, not pointers. So use a more appropriate type.
- Only check the least significant bit of the tagged pointers. Masking
with 3/~3 is unnecessary and confusing.
- Introduce the TB_FOR_EACH_TAGGED macro, and use it to define
PAGE_FOR_EACH_TB, which improves readability. Note that
TB_FOR_EACH_TAGGED will gain another user in a subsequent patch.
- Update tb_page_remove to use PAGE_FOR_EACH_TB. In case there
is a bug and we attempt to remove a TB that is not in the list, instead
of segfaulting (since the list is NULL-terminated) we will reach
g_assert_not_reached().
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Thereby making it per-TCGContext. Once we remove tb_lock, this will
avoid an atomic increment every time a TB is invalidated.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This paves the way for enabling scalable parallel generation of TCG code.
Instead of tracking TBs with a single binary search tree (BST), use a
BST for each TCG region, protecting it with a lock. This is as scalable
as it gets, since each TCG thread operates on a separate region.
The core of this change is the introduction of struct tcg_region_tree,
which contains a pointer to a GTree and an associated lock to serialize
accesses to it. We then allocate an array of tcg_region_tree's, adding
the appropriate padding to avoid false sharing based on
qemu_dcache_linesize.
Given a tc_ptr, we first find the corresponding region_tree. This
is done by special-casing the first and last regions first, since they
might be of size != region.size; otherwise we just divide the offset
by region.stride. I was worried about this division (several dozen
cycles of latency), but profiling shows that this is not a fast path.
Note that region.stride is not required to be a power of two; it
is only required to be a multiple of the host's page size.
Note that with this design we can also provide consistent snapshots
about all region trees at once; for instance, tcg_tb_foreach
acquires/releases all region_tree locks before/after iterating over them.
For this reason we now drop tb_lock in dump_exec_info().
As an alternative I considered implementing a concurrent BST, but this
can be tricky to get right, offers no consistent snapshots of the BST,
and performance and scalability-wise I don't think it could ever beat
having separate GTrees, given that our workload is insert-mostly (all
concurrent BST designs I've seen focus, understandably, on making
lookups fast, which comes at the expense of convoluted, non-wait-free
insertions/removals).
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The meaning of "existing" is now changed to "matches in hash and
ht->cmp result". This is saner than just checking the pointer value.
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
qht_lookup now uses the default cmp function. qht_lookup_custom is defined
to retain the old behaviour, that is a cmp function is explicitly provided.
qht_insert will gain use of the default cmp in the next patch.
Note that we move qht_lookup_custom's @func to be the last argument,
which makes the new qht_lookup as simple as possible.
Instead of this (i.e. keeping @func 2nd):
0000000000010750 <qht_lookup>:
10750: 89 d1 mov %edx,%ecx
10752: 48 89 f2 mov %rsi,%rdx
10755: 48 8b 77 08 mov 0x8(%rdi),%rsi
10759: e9 22 ff ff ff jmpq 10680 <qht_lookup_custom>
1075e: 66 90 xchg %ax,%ax
We get:
0000000000010740 <qht_lookup>:
10740: 48 8b 4f 08 mov 0x8(%rdi),%rcx
10744: e9 37 ff ff ff jmpq 10680 <qht_lookup_custom>
10749: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Currently we don't support board configurations that put an IOMMU
in the path of the CPU's memory transactions, and instead just
assert() if the memory region fonud in address_space_translate_for_iotlb()
is an IOMMUMemoryRegion.
Remove this limitation by having the function handle IOMMUs.
This is mostly straightforward, but we must make sure we have
a notifier registered for every IOMMU that a transaction has
passed through, so that we can flush the TLB appropriately
when any of the IOMMUs change their mappings.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20180604152941.20374-5-peter.maydell@linaro.org
The API for cpu_transaction_failed() says that it takes the physical
address for the failed transaction. However we were actually passing
it the offset within the target MemoryRegion. We don't currently
have any target CPU implementations of this hook that require the
physical address; fix this bug so we don't get confused if we ever
do add one.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180611125633.32755-3-peter.maydell@linaro.org
The 'addr' field in the CPUIOTLBEntry struct has a rather non-obvious
use; add a comment documenting it (reverse-engineered from what
the code that sets it is doing).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180611125633.32755-2-peter.maydell@linaro.org
As part of plumbing MemTxAttrs down to the IOMMU translate method,
add MemTxAttrs as an argument to address_space_translate()
and address_space_translate_cached(). Callers either have an
attrs value to hand, or don't care and can use MEMTXATTRS_UNSPECIFIED.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180521140402.23318-4-peter.maydell@linaro.org
As part of plumbing MemTxAttrs down to the IOMMU translate method,
add MemTxAttrs as an argument to tb_invalidate_phys_addr().
Its callers either have an attrs value to hand, or don't care
and can use MEMTXATTRS_UNSPECIFIED.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20180521140402.23318-3-peter.maydell@linaro.org
Usually the logging of the CPU state produced by -d cpu is sufficient
to diagnose problems, but sometimes you want to see the state of
the floating point registers as well. We don't want to enable that
by default as it adds a lot of extra data to the log; instead,
allow it to be optionally enabled via -d fpu.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180510130024.31678-1-peter.maydell@linaro.org
* hw/arm/iotkit.c: fix minor memory leak
* softfloat: fix wrong-exception-flags bug for multiply-add corner case
* arm: isolate and clean up DTB generation
* implement Arm v8.1-Atomics extension
* Fix some bugs and missing instructions in the v8.2-FP16 extension
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Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20180510' into staging
target-arm queue:
* hw/arm/iotkit.c: fix minor memory leak
* softfloat: fix wrong-exception-flags bug for multiply-add corner case
* arm: isolate and clean up DTB generation
* implement Arm v8.1-Atomics extension
* Fix some bugs and missing instructions in the v8.2-FP16 extension
# gpg: Signature made Thu 10 May 2018 18:44:34 BST
# gpg: using RSA key 3C2525ED14360CDE
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>"
# gpg: aka "Peter Maydell <pmaydell@gmail.com>"
# gpg: aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>"
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83 15CF 3C25 25ED 1436 0CDE
* remotes/pmaydell/tags/pull-target-arm-20180510: (21 commits)
target/arm: Clear SVE high bits for FMOV
target/arm: Fix float16 to/from int16
target/arm: Implement vector shifted FCVT for fp16
target/arm: Implement vector shifted SCVF/UCVF for fp16
target/arm: Enable ARM_FEATURE_V8_ATOMICS for user-only
target/arm: Implement CAS and CASP
target/arm: Fill in disas_ldst_atomic
target/arm: Introduce ARM_FEATURE_V8_ATOMICS and initial decode
target/riscv: Use new atomic min/max expanders
tcg: Use GEN_ATOMIC_HELPER_FN for opposite endian atomic add
tcg: Introduce atomic helpers for integer min/max
target/xtensa: Use new min/max expanders
target/arm: Use new min/max expanders
tcg: Introduce helpers for integer min/max
atomic.h: Work around gcc spurious "unused value" warning
make sure that we aren't overwriting mc->get_hotplug_handler by accident
arm/boot: split load_dtb() from arm_load_kernel()
platform-bus-device: use device plug callback instead of machine_done notifier
pc: simplify MachineClass::get_hotplug_handler handling
softfloat: Handle default NaN mode after pickNaNMulAdd, not before
...
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
# Conflicts:
# target/riscv/translate.c
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180508151437.4232-6-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Given that this atomic operation will be used by both risc-v
and aarch64, let's not duplicate code across the two targets.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180508151437.4232-5-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
While at it, use int for both num_insns and max_insns to make
sure we have same-type comparisons.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
In icount mode, instructions that access io memory spaces in the middle
of the translation block invoke TB recompilation. After recompilation,
such instructions become last in the TB and are allowed to access io
memory spaces.
When the code includes instruction like i386 'xchg eax, 0xffffd080'
which accesses APIC, QEMU goes into an infinite loop of the recompilation.
This instruction includes two memory accesses - one read and one write.
After the first access, APIC calls cpu_report_tpr_access, which restores
the CPU state to get the current eip. But cpu_restore_state_from_tb
resets the cpu->can_do_io flag which makes the second memory access invalid.
Therefore the second memory access causes a recompilation of the block.
Then these operations repeat again and again.
This patch moves resetting cpu->can_do_io flag from
cpu_restore_state_from_tb to cpu_loop_exit* functions.
It also adds a parameter for cpu_restore_state which controls restoring
icount. There is no need to restore icount when we only query CPU state
without breaking the TB. Restoring it in such cases leads to the
incorrect flow of the virtual time.
In most cases new parameter is true (icount should be recalculated).
But there are two cases in i386 and openrisc when the CPU state is only
queried without the need to break the TB. This patch fixes both of
these cases.
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-Id: <20180409091320.12504.35329.stgit@pasha-VirtualBox>
[rth: Make can_do_io setting unconditional; move from cpu_exec;
make cpu_loop_exit_{noexc,restore} call cpu_loop_exit.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
A mistake in the type passed to sizeof, that happens to work
when the out-of-line fallback itself is using host vectors,
but fails when using only the base types.
Tested-by: Emilio G. Cota <cota@braap.org>
Reported-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
We have confused the number of instructions that have been
executed in the TB with the number of instructions needed
to repeat the I/O instruction.
We have used cpu_restore_state_from_tb, which means that
the guest pc is pointing to the I/O instruction. The only
time the answer to the later question is not 1 is when
MIPS or SH4 need to re-execute the branch for the delay
slot as well.
We must rely on cpu->cflags_next_tb to generate the next TB,
as otherwise we have a race condition with other guest cpus
within the TB cache.
Fixes: 0790f86861
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20180319031545.29359-1-richard.henderson@linaro.org>
Tested-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
cpu_io_recompile() function was broken by
the commit 9b990ee5a3. Instead of regenerating
the block starting from PC of the original block, it just set the instruction
counter for TCG. In most cases this was unnoticed, but in icount mode
there was an exception for incorrect usage of CF_LAST_IO flag.
This patch recovers recompilation of the original block and also
configures translation for executing single IO instruction which
caused a recompilation.
Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <20180227095338.1060.27385.stgit@pasha-VirtualBox>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Function cpu_handle_interrupt calls cc->cpu_exec_interrupt to process
pending hardware interrupts. Under the hood cpu_exec_interrupt uses
cpu->exception_index to pass information to the internal function which
is usually common for exception and interrupt processing.
But this value is not reset after return and may be processed again
by cpu_handle_exception. This does not happen due to overwriting
the exception_index at the end of cpu_handle_interrupt.
But this branch may also overwrite the valid exception_index in some cases.
Therefore this patch:
1. resets exception_index just after the call to cpu_exec_interrupt
2. prevents overwriting the meaningful value of exception_index
Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20180227095140.1060.61357.stgit@pasha-VirtualBox>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Use dup to convert a non-constant scalar to a third vector.
Add addition, multiplication, and logical operations with an immediate.
Add addition, subtraction, multiplication, and logical operations with
a non-constant scalar. Allow for the front-end to build operations in
which the scalar operand comes first.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
No vector ops as yet. SSE only has direct support for 8- and 16-bit
saturation; handling 32- and 64-bit saturation is much more expensive.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Opcodes are added for scalar and vector shifts, but considering the
varied semantics of these do not expose them to the front ends. Do
go ahead and provide them in case they are needed for backend expansion.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
We dropped support for ia64 host CPUs in the 2.11 release (removing
the TCG backend for it, and advertising the support as being
completely removed in the changelog). However there are a few bits
and pieces of code still floating about. Remove those, too.
We can drop the check in configure for "ia64 or hppa host?"
entirely, because we don't support hppa hosts either any more.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <1516897189-11035-1-git-send-email-peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The MC68040 MMU provides the size of the access that
triggers the page fault.
This size is set in the Special Status Word which
is written in the stack frame of the access fault
exception.
So we need the size in m68k_cpu_unassigned_access() and
m68k_cpu_handle_mmu_fault().
To be able to do that, this patch modifies the prototype of
handle_mmu_fault handler, tlb_fill() and probe_write().
do_unassigned_access() already includes a size parameter.
This patch also updates handle_mmu_fault handlers and
tlb_fill() of all targets (only parameter, no code change).
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20180118193846.24953-2-laurent@vivier.eu>
If multiple guest threads in user-mode emulation write to a
page which QEMU has marked read-only because of cached TCG
translations, the threads can race in page_unprotect:
* threads A & B both try to do a write to a page with code in it at
the same time (ie which we've made non-writeable, so SEGV)
* they race into the signal handler with this faulting address
* thread A happens to get to page_unprotect() first and takes the
mmap lock, so thread B sits waiting for it to be done
* A then finds the page, marks it PAGE_WRITE and mprotect()s it writable
* A can then continue OK (returns from signal handler to retry the
memory access)
* ...but when B gets the mmap lock it finds that the page is already
PAGE_WRITE, and so it exits page_unprotect() via the "not due to
protected translation" code path, and wrongly delivers the signal
to the guest rather than just retrying the access
In particular, this meant that trying to run 'javac' in user-mode
emulation would fail with a spurious guest SIGSEGV.
Handle this by making page_unprotect() assume that a call for a page
which is already PAGE_WRITE is due to a race of this sort and return
a "fault handled" indication.
Since this would cause an infinite loop if we ever called
page_unprotect() for some other kind of fault than "write failed due
to bad access permissions", tighten the condition in
handle_cpu_signal() to check the signal number and si_code, and add a
comment so that if somebody does ever find themselves debugging an
infinite loop of faults they have some clue about why.
(The trick for identifying the correct setting for
current_tb_invalidated for thread B (needed to handle the precise-SMC
case) is due to Richard Henderson. Paolo Bonzini suggested just
relying on si_code rather than trying anything more complicated.)
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <1511879725-9576-3-git-send-email-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Currently all the architecture/OS specific cpu_signal_handler()
functions call handle_cpu_signal() without passing it the
siginfo_t. We're going to want that so we can look at the si_code
to determine whether this is a SEGV_ACCERR access violation or
some other kind of fault, so change the functions to pass through
the pointer to the siginfo_t rather than just the si_addr value.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <1511879725-9576-2-git-send-email-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20171217055023.29225-1-pbonzini@redhat.com>
[rth: Also change the Chain logging in helper_lookup_tb_ptr.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The conditional memory barrier not only looks strange but actually is
wrong.
On s390x, I can reproduce interrupts via cpu_interrupt() not leading to
a proper kick out of emulation every now and then. cpu_interrupt() is
especially used for inter CPU communication via SIGP (esp. external
calls and emergency interrupts).
With this patch, I was not able to reproduce. (esp. no stalls or hangs
in the guest).
My setup is s390x MTTCG with 16 VCPUs on 8 CPU host, running make -j16.
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20171129191319.11483-1-david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
exec: housekeeping (funny since 02d0e09503)
applied using ./scripts/clean-includes
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
The cpu-exec-common.c file includes memory-internal.h, but it doesn't
actually use anything from that header. Remove the unnecessary include.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
To do a write to memory that is marked as notdirty, we need
to invalidate any TBs we have cached for that memory, and
update the cpu physical memory dirty flags for VGA and migration.
The slowpath code in notdirty_mem_write() does all this correctly,
but the new atomic handling code in atomic_mmu_lookup() doesn't
do anything at all, it just clears the dirty bit in the TLB.
The effect of this bug is that if the first write to a notdirty
page for which we have cached TBs is by a guest atomic access,
we fail to invalidate the TBs and subsequently will execute
incorrect code. This can be seen by trying to run 'javac' on AArch64.
Use the new notdirty_call_before() and notdirty_call_after()
functions to correctly handle the update to notdirty memory
in the atomic codepath.
Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 1511201308-23580-3-git-send-email-peter.maydell@linaro.org
When we handle a signal from a fault within a user-only memory helper,
we cannot cpu_restore_state with the PC found within the signal frame.
Use a TLS variable, helper_retaddr, to record the unwind start point
to find the faulting guest insn.
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This patch ensures that icount_decr.u32.high is clear before calling
cpu_exec_nocache when exception is pending. Because the exception is
caused by the first instruction in the block and it cannot be executed
without resetting the flag.
There are two parts in the fix. First, clear icount_decr.u32.high in
cpu_handle_interrupt (just before processing the "dependent" request,
stored in cpu->interrupt_request or cpu->exit_request) rather than
cpu_loop_exec_tb; this ensures that cpu_handle_exception is always
reached with zero icount_decr.u32.high unless another interrupt has
happened in the meanwhile.
Second, try to cause the exception at the beginning of
cpu_handle_exception, and exit immediately if the TB cannot
execute. With this change, interrupts are processed and
cpu_exec_nocache can make process.
Signed-off-by: Maria Klimushenkova <maria.klimushenkova@ispras.ru>
Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <20171114081818.27640.33165.stgit@pasha-VirtualBox>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This patch adds a condition before overwriting exception_index fiels.
It is needed when exception_index is already set to some meaningful value.
Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <20171114081812.27640.26372.stgit@pasha-VirtualBox>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We are still seeing signals during translation time when we walk over
a page protection boundary. This expands the check to ensure the host
PC is inside the code generation buffer. The original suggestion was
to check versus tcg_ctx.code_gen_ptr but as we now segment the
translation buffer we have to settle for just a general check for
being inside.
I've also fixed up the declaration to make it clear it can deal with
invalid addresses. A later patch will fix up the call sites.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20171108153245.20740-2-alex.bennee@linaro.org
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Tested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Commit ac03ee5331 narrowed the scope of the exclusive
region so it only covers when we're executing the TB, not when
we're generating it. However it missed that there is more than
one execution path out of cpu_tb_exec -- if the atomic insn
causes an exception then the code will longjmp out, skipping
the code to end the exclusive region. This causes QEMU to hang
the next time the CPU calls start_exclusive(), waiting for
itself to exit the region.
Move the "end the region" code out to the end of the
function so that it is run for both normal exit and also
for exit-via-longjmp. We have to use a volatile bool flag
to decide whether we need to end the region, because we
can longjump out of the codegen as well as the execution.
(For some reason this only reproduces for me with a clang
optimized build, not a gcc debug build.)
Reviewed-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Fixes: ac03ee5331
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <1509640536-32160-1-git-send-email-peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Two or more threads might race while invalidating the same TB. We currently
do not check for this at all despite taking tb_lock, which means we would
wrongly invalidate the same TB more than once. This bug has actually been
hit by users: I recently saw a report on IRC, although I have yet to see
the corresponding test case.
Fix this by using qht_remove as the synchronization point; if it fails,
that means the TB has already been invalidated, and therefore there
is nothing left to do in tb_phys_invalidate.
Note that this solution works now that we still have tb_lock, and will
continue working once we remove tb_lock.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <1508445114-4717-1-git-send-email-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This enables parallel TCG code generation. However, we do not take
advantage of it yet since tb_lock is still held during tb_gen_code.
In user-mode we use a single TCG context; see the documentation
added to tcg_region_init for the rationale.
Note that targets do not need any conversion: targets initialize a
TCGContext (e.g. defining TCG globals), and after this initialization
has finished, the context is cloned by the vCPU threads, each of
them keeping a separate copy.
TCG threads claim one entry in tcg_ctxs[] by atomically increasing
n_tcg_ctxs. Do not be too annoyed by the subsequent atomic_read's
of that variable and tcg_ctxs; they are there just to play nice with
analysis tools such as thread sanitizer.
Note that we do not allocate an array of contexts (we allocate
an array of pointers instead) because when tcg_context_init
is called, we do not know yet how many contexts we'll use since
the bool behind qemu_tcg_mttcg_enabled() isn't set yet.
Previous patches folded some TCG globals into TCGContext. The non-const
globals remaining are only set at init time, i.e. before the TCG
threads are spawned. Here is a list of these set-at-init-time globals
under tcg/:
Only written by tcg_context_init:
- indirect_reg_alloc_order
- tcg_op_defs
Only written by tcg_target_init (called from tcg_context_init):
- tcg_target_available_regs
- tcg_target_call_clobber_regs
- arm: arm_arch, use_idiv_instructions
- i386: have_cmov, have_bmi1, have_bmi2, have_lzcnt,
have_movbe, have_popcnt
- mips: use_movnz_instructions, use_mips32_instructions,
use_mips32r2_instructions, got_sigill (tcg_target_detect_isa)
- ppc: have_isa_2_06, have_isa_3_00, tb_ret_addr
- s390: tb_ret_addr, s390_facilities
- sparc: qemu_ld_trampoline, qemu_st_trampoline (build_trampolines),
use_vis3_instructions
Only written by tcg_prologue_init:
- 'struct jit_code_entry one_entry'
- aarch64: tb_ret_addr
- arm: tb_ret_addr
- i386: tb_ret_addr, guest_base_flags
- ia64: tb_ret_addr
- mips: tb_ret_addr, bswap32_addr, bswap32u_addr, bswap64_addr
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
