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qemu/target/arm/op_helper.c
Peter Maydell 5b2c8af89b target/arm: Make WFI a NOP for userspace emulators 
The WFI insn is not system-mode only, though it doesn't usually make
a huge amount of sense for userspace code to execute it.  Currently
if you try it in qemu-arm then the helper function will raise an
EXCP_HLT exception, which is not covered by the switch in cpu_loop()
and results in an abort:

qemu: unhandled CPU exception 0x10001 - aborting
R00=00000001 R01=408003e4 R02=408003ec R03=000102ec
R04=00010a28 R05=00010158 R06=00087460 R07=00010158
R08=00000000 R09=00000000 R10=00085b7c R11=408002a4
R12=408002b8 R13=408002a0 R14=0001057c R15=000102f8
PSR=60000010 -ZC- A usr32
qemu:handle_cpu_signal received signal outside vCPU context @ pc=0x7fcbfa4f0a12

Make the WFI helper function return immediately in the usermode
emulator. This turns WFI into a NOP, which is OK because:
 * architecturally "WFI is a NOP" is a permitted implementation
 * aarch64 Linux kernels use the SCTLR_EL1.nTWI bit to trap
   userspace WFI and NOP it (though aarch32 kernels currently
   just let WFI do whatever it would do)

We could in theory make the translate.c code special case user-mode
emulation and NOP the insn entirely rather than making the helper
do nothing, but because no real world code will be trying to
execute WFI we don't care about efficiency and the helper provides
a single place where we can make the change rather than having
to touch multiple places in translate.c and translate-a64.c.

Fixes: https://bugs.launchpad.net/qemu/+bug/1926759
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210430162212.825-1-peter.maydell@linaro.org
2021-05-10 13:24:09 +01:00

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/*
* ARM helper routines
*
* Copyright (c) 2005-2007 CodeSourcery, LLC
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu/main-loop.h"
#include "cpu.h"
#include "exec/helper-proto.h"
#include "internals.h"
#include "exec/exec-all.h"
#include "exec/cpu_ldst.h"
#define SIGNBIT (uint32_t)0x80000000
#define SIGNBIT64 ((uint64_t)1 << 63)
static CPUState *do_raise_exception(CPUARMState *env, uint32_t excp,
uint32_t syndrome, uint32_t target_el)
{
CPUState *cs = env_cpu(env);
if (target_el == 1 && (arm_hcr_el2_eff(env) & HCR_TGE)) {
/*
* Redirect NS EL1 exceptions to NS EL2. These are reported with
* their original syndrome register value, with the exception of
* SIMD/FP access traps, which are reported as uncategorized
* (see DDI0478C.a D1.10.4)
*/
target_el = 2;
if (syn_get_ec(syndrome) == EC_ADVSIMDFPACCESSTRAP) {
syndrome = syn_uncategorized();
}
}
assert(!excp_is_internal(excp));
cs->exception_index = excp;
env->exception.syndrome = syndrome;
env->exception.target_el = target_el;
return cs;
}
void raise_exception(CPUARMState *env, uint32_t excp,
uint32_t syndrome, uint32_t target_el)
{
CPUState *cs = do_raise_exception(env, excp, syndrome, target_el);
cpu_loop_exit(cs);
}
void raise_exception_ra(CPUARMState *env, uint32_t excp, uint32_t syndrome,
uint32_t target_el, uintptr_t ra)
{
CPUState *cs = do_raise_exception(env, excp, syndrome, target_el);
cpu_loop_exit_restore(cs, ra);
}
uint64_t HELPER(neon_tbl)(CPUARMState *env, uint32_t desc,
uint64_t ireg, uint64_t def)
{
uint64_t tmp, val = 0;
uint32_t maxindex = ((desc & 3) + 1) * 8;
uint32_t base_reg = desc >> 2;
uint32_t shift, index, reg;
for (shift = 0; shift < 64; shift += 8) {
index = (ireg >> shift) & 0xff;
if (index < maxindex) {
reg = base_reg + (index >> 3);
tmp = *aa32_vfp_dreg(env, reg);
tmp = ((tmp >> ((index & 7) << 3)) & 0xff) << shift;
} else {
tmp = def & (0xffull << shift);
}
val |= tmp;
}
return val;
}
void HELPER(v8m_stackcheck)(CPUARMState *env, uint32_t newvalue)
{
/*
* Perform the v8M stack limit check for SP updates from translated code,
* raising an exception if the limit is breached.
*/
if (newvalue < v7m_sp_limit(env)) {
CPUState *cs = env_cpu(env);
/*
* Stack limit exceptions are a rare case, so rather than syncing
* PC/condbits before the call, we use cpu_restore_state() to
* get them right before raising the exception.
*/
cpu_restore_state(cs, GETPC(), true);
raise_exception(env, EXCP_STKOF, 0, 1);
}
}
uint32_t HELPER(add_setq)(CPUARMState *env, uint32_t a, uint32_t b)
{
uint32_t res = a + b;
if (((res ^ a) & SIGNBIT) && !((a ^ b) & SIGNBIT))
env->QF = 1;
return res;
}
uint32_t HELPER(add_saturate)(CPUARMState *env, uint32_t a, uint32_t b)
{
uint32_t res = a + b;
if (((res ^ a) & SIGNBIT) && !((a ^ b) & SIGNBIT)) {
env->QF = 1;
res = ~(((int32_t)a >> 31) ^ SIGNBIT);
}
return res;
}
uint32_t HELPER(sub_saturate)(CPUARMState *env, uint32_t a, uint32_t b)
{
uint32_t res = a - b;
if (((res ^ a) & SIGNBIT) && ((a ^ b) & SIGNBIT)) {
env->QF = 1;
res = ~(((int32_t)a >> 31) ^ SIGNBIT);
}
return res;
}
uint32_t HELPER(add_usaturate)(CPUARMState *env, uint32_t a, uint32_t b)
{
uint32_t res = a + b;
if (res < a) {
env->QF = 1;
res = ~0;
}
return res;
}
uint32_t HELPER(sub_usaturate)(CPUARMState *env, uint32_t a, uint32_t b)
{
uint32_t res = a - b;
if (res > a) {
env->QF = 1;
res = 0;
}
return res;
}
/* Signed saturation. */
static inline uint32_t do_ssat(CPUARMState *env, int32_t val, int shift)
{
int32_t top;
uint32_t mask;
top = val >> shift;
mask = (1u << shift) - 1;
if (top > 0) {
env->QF = 1;
return mask;
} else if (top < -1) {
env->QF = 1;
return ~mask;
}
return val;
}
/* Unsigned saturation. */
static inline uint32_t do_usat(CPUARMState *env, int32_t val, int shift)
{
uint32_t max;
max = (1u << shift) - 1;
if (val < 0) {
env->QF = 1;
return 0;
} else if (val > max) {
env->QF = 1;
return max;
}
return val;
}
/* Signed saturate. */
uint32_t HELPER(ssat)(CPUARMState *env, uint32_t x, uint32_t shift)
{
return do_ssat(env, x, shift);
}
/* Dual halfword signed saturate. */
uint32_t HELPER(ssat16)(CPUARMState *env, uint32_t x, uint32_t shift)
{
uint32_t res;
res = (uint16_t)do_ssat(env, (int16_t)x, shift);
res |= do_ssat(env, ((int32_t)x) >> 16, shift) << 16;
return res;
}
/* Unsigned saturate. */
uint32_t HELPER(usat)(CPUARMState *env, uint32_t x, uint32_t shift)
{
return do_usat(env, x, shift);
}
/* Dual halfword unsigned saturate. */
uint32_t HELPER(usat16)(CPUARMState *env, uint32_t x, uint32_t shift)
{
uint32_t res;
res = (uint16_t)do_usat(env, (int16_t)x, shift);
res |= do_usat(env, ((int32_t)x) >> 16, shift) << 16;
return res;
}
void HELPER(setend)(CPUARMState *env)
{
env->uncached_cpsr ^= CPSR_E;
arm_rebuild_hflags(env);
}
#ifndef CONFIG_USER_ONLY
/* Function checks whether WFx (WFI/WFE) instructions are set up to be trapped.
* The function returns the target EL (1-3) if the instruction is to be trapped;
* otherwise it returns 0 indicating it is not trapped.
*/
static inline int check_wfx_trap(CPUARMState *env, bool is_wfe)
{
int cur_el = arm_current_el(env);
uint64_t mask;
if (arm_feature(env, ARM_FEATURE_M)) {
/* M profile cores can never trap WFI/WFE. */
return 0;
}
/* If we are currently in EL0 then we need to check if SCTLR is set up for
* WFx instructions being trapped to EL1. These trap bits don't exist in v7.
*/
if (cur_el < 1 && arm_feature(env, ARM_FEATURE_V8)) {
int target_el;
mask = is_wfe ? SCTLR_nTWE : SCTLR_nTWI;
if (arm_is_secure_below_el3(env) && !arm_el_is_aa64(env, 3)) {
/* Secure EL0 and Secure PL1 is at EL3 */
target_el = 3;
} else {
target_el = 1;
}
if (!(env->cp15.sctlr_el[target_el] & mask)) {
return target_el;
}
}
/* We are not trapping to EL1; trap to EL2 if HCR_EL2 requires it
* No need for ARM_FEATURE check as if HCR_EL2 doesn't exist the
* bits will be zero indicating no trap.
*/
if (cur_el < 2) {
mask = is_wfe ? HCR_TWE : HCR_TWI;
if (arm_hcr_el2_eff(env) & mask) {
return 2;
}
}
/* We are not trapping to EL1 or EL2; trap to EL3 if SCR_EL3 requires it */
if (cur_el < 3) {
mask = (is_wfe) ? SCR_TWE : SCR_TWI;
if (env->cp15.scr_el3 & mask) {
return 3;
}
}
return 0;
}
#endif
void HELPER(wfi)(CPUARMState *env, uint32_t insn_len)
{
#ifdef CONFIG_USER_ONLY
/*
* WFI in the user-mode emulator is technically permitted but not
* something any real-world code would do. AArch64 Linux kernels
* trap it via SCTRL_EL1.nTWI and make it an (expensive) NOP;
* AArch32 kernels don't trap it so it will delay a bit.
* For QEMU, make it NOP here, because trying to raise EXCP_HLT
* would trigger an abort.
*/
return;
#else
CPUState *cs = env_cpu(env);
int target_el = check_wfx_trap(env, false);
if (cpu_has_work(cs)) {
/* Don't bother to go into our "low power state" if
* we would just wake up immediately.
*/
return;
}
if (target_el) {
if (env->aarch64) {
env->pc -= insn_len;
} else {
env->regs[15] -= insn_len;
}
raise_exception(env, EXCP_UDEF, syn_wfx(1, 0xe, 0, insn_len == 2),
target_el);
}
cs->exception_index = EXCP_HLT;
cs->halted = 1;
cpu_loop_exit(cs);
#endif
}
void HELPER(wfe)(CPUARMState *env)
{
/* This is a hint instruction that is semantically different
* from YIELD even though we currently implement it identically.
* Don't actually halt the CPU, just yield back to top
* level loop. This is not going into a "low power state"
* (ie halting until some event occurs), so we never take
* a configurable trap to a different exception level.
*/
HELPER(yield)(env);
}
void HELPER(yield)(CPUARMState *env)
{
CPUState *cs = env_cpu(env);
/* This is a non-trappable hint instruction that generally indicates
* that the guest is currently busy-looping. Yield control back to the
* top level loop so that a more deserving VCPU has a chance to run.
*/
cs->exception_index = EXCP_YIELD;
cpu_loop_exit(cs);
}
/* Raise an internal-to-QEMU exception. This is limited to only
* those EXCP values which are special cases for QEMU to interrupt
* execution and not to be used for exceptions which are passed to
* the guest (those must all have syndrome information and thus should
* use exception_with_syndrome).
*/
void HELPER(exception_internal)(CPUARMState *env, uint32_t excp)
{
CPUState *cs = env_cpu(env);
assert(excp_is_internal(excp));
cs->exception_index = excp;
cpu_loop_exit(cs);
}
/* Raise an exception with the specified syndrome register value */
void HELPER(exception_with_syndrome)(CPUARMState *env, uint32_t excp,
uint32_t syndrome, uint32_t target_el)
{
raise_exception(env, excp, syndrome, target_el);
}
/* Raise an EXCP_BKPT with the specified syndrome register value,
* targeting the correct exception level for debug exceptions.
*/
void HELPER(exception_bkpt_insn)(CPUARMState *env, uint32_t syndrome)
{
int debug_el = arm_debug_target_el(env);
int cur_el = arm_current_el(env);
/* FSR will only be used if the debug target EL is AArch32. */
env->exception.fsr = arm_debug_exception_fsr(env);
/* FAR is UNKNOWN: clear vaddress to avoid potentially exposing
* values to the guest that it shouldn't be able to see at its
* exception/security level.
*/
env->exception.vaddress = 0;
/*
* Other kinds of architectural debug exception are ignored if
* they target an exception level below the current one (in QEMU
* this is checked by arm_generate_debug_exceptions()). Breakpoint
* instructions are special because they always generate an exception
* to somewhere: if they can't go to the configured debug exception
* level they are taken to the current exception level.
*/
if (debug_el < cur_el) {
debug_el = cur_el;
}
raise_exception(env, EXCP_BKPT, syndrome, debug_el);
}
uint32_t HELPER(cpsr_read)(CPUARMState *env)
{
return cpsr_read(env) & ~CPSR_EXEC;
}
void HELPER(cpsr_write)(CPUARMState *env, uint32_t val, uint32_t mask)
{
cpsr_write(env, val, mask, CPSRWriteByInstr);
/* TODO: Not all cpsr bits are relevant to hflags. */
arm_rebuild_hflags(env);
}
/* Write the CPSR for a 32-bit exception return */
void HELPER(cpsr_write_eret)(CPUARMState *env, uint32_t val)
{
uint32_t mask;
qemu_mutex_lock_iothread();
arm_call_pre_el_change_hook(env_archcpu(env));
qemu_mutex_unlock_iothread();
mask = aarch32_cpsr_valid_mask(env->features, &env_archcpu(env)->isar);
cpsr_write(env, val, mask, CPSRWriteExceptionReturn);
/* Generated code has already stored the new PC value, but
* without masking out its low bits, because which bits need
* masking depends on whether we're returning to Thumb or ARM
* state. Do the masking now.
*/
env->regs[15] &= (env->thumb ? ~1 : ~3);
arm_rebuild_hflags(env);
qemu_mutex_lock_iothread();
arm_call_el_change_hook(env_archcpu(env));
qemu_mutex_unlock_iothread();
}
/* Access to user mode registers from privileged modes. */
uint32_t HELPER(get_user_reg)(CPUARMState *env, uint32_t regno)
{
uint32_t val;
if (regno == 13) {
val = env->banked_r13[BANK_USRSYS];
} else if (regno == 14) {
val = env->banked_r14[BANK_USRSYS];
} else if (regno >= 8
&& (env->uncached_cpsr & 0x1f) == ARM_CPU_MODE_FIQ) {
val = env->usr_regs[regno - 8];
} else {
val = env->regs[regno];
}
return val;
}
void HELPER(set_user_reg)(CPUARMState *env, uint32_t regno, uint32_t val)
{
if (regno == 13) {
env->banked_r13[BANK_USRSYS] = val;
} else if (regno == 14) {
env->banked_r14[BANK_USRSYS] = val;
} else if (regno >= 8
&& (env->uncached_cpsr & 0x1f) == ARM_CPU_MODE_FIQ) {
env->usr_regs[regno - 8] = val;
} else {
env->regs[regno] = val;
}
}
void HELPER(set_r13_banked)(CPUARMState *env, uint32_t mode, uint32_t val)
{
if ((env->uncached_cpsr & CPSR_M) == mode) {
env->regs[13] = val;
} else {
env->banked_r13[bank_number(mode)] = val;
}
}
uint32_t HELPER(get_r13_banked)(CPUARMState *env, uint32_t mode)
{
if ((env->uncached_cpsr & CPSR_M) == ARM_CPU_MODE_SYS) {
/* SRS instruction is UNPREDICTABLE from System mode; we UNDEF.
* Other UNPREDICTABLE and UNDEF cases were caught at translate time.
*/
raise_exception(env, EXCP_UDEF, syn_uncategorized(),
exception_target_el(env));
}
if ((env->uncached_cpsr & CPSR_M) == mode) {
return env->regs[13];
} else {
return env->banked_r13[bank_number(mode)];
}
}
static void msr_mrs_banked_exc_checks(CPUARMState *env, uint32_t tgtmode,
uint32_t regno)
{
/* Raise an exception if the requested access is one of the UNPREDICTABLE
* cases; otherwise return. This broadly corresponds to the pseudocode
* BankedRegisterAccessValid() and SPSRAccessValid(),
* except that we have already handled some cases at translate time.
*/
int curmode = env->uncached_cpsr & CPSR_M;
if (regno == 17) {
/* ELR_Hyp: a special case because access from tgtmode is OK */
if (curmode != ARM_CPU_MODE_HYP && curmode != ARM_CPU_MODE_MON) {
goto undef;
}
return;
}
if (curmode == tgtmode) {
goto undef;
}
if (tgtmode == ARM_CPU_MODE_USR) {
switch (regno) {
case 8 ... 12:
if (curmode != ARM_CPU_MODE_FIQ) {
goto undef;
}
break;
case 13:
if (curmode == ARM_CPU_MODE_SYS) {
goto undef;
}
break;
case 14:
if (curmode == ARM_CPU_MODE_HYP || curmode == ARM_CPU_MODE_SYS) {
goto undef;
}
break;
default:
break;
}
}
if (tgtmode == ARM_CPU_MODE_HYP) {
/* SPSR_Hyp, r13_hyp: accessible from Monitor mode only */
if (curmode != ARM_CPU_MODE_MON) {
goto undef;
}
}
return;
undef:
raise_exception(env, EXCP_UDEF, syn_uncategorized(),
exception_target_el(env));
}
void HELPER(msr_banked)(CPUARMState *env, uint32_t value, uint32_t tgtmode,
uint32_t regno)
{
msr_mrs_banked_exc_checks(env, tgtmode, regno);
switch (regno) {
case 16: /* SPSRs */
env->banked_spsr[bank_number(tgtmode)] = value;
break;
case 17: /* ELR_Hyp */
env->elr_el[2] = value;
break;
case 13:
env->banked_r13[bank_number(tgtmode)] = value;
break;
case 14:
env->banked_r14[r14_bank_number(tgtmode)] = value;
break;
case 8 ... 12:
switch (tgtmode) {
case ARM_CPU_MODE_USR:
env->usr_regs[regno - 8] = value;
break;
case ARM_CPU_MODE_FIQ:
env->fiq_regs[regno - 8] = value;
break;
default:
g_assert_not_reached();
}
break;
default:
g_assert_not_reached();
}
}
uint32_t HELPER(mrs_banked)(CPUARMState *env, uint32_t tgtmode, uint32_t regno)
{
msr_mrs_banked_exc_checks(env, tgtmode, regno);
switch (regno) {
case 16: /* SPSRs */
return env->banked_spsr[bank_number(tgtmode)];
case 17: /* ELR_Hyp */
return env->elr_el[2];
case 13:
return env->banked_r13[bank_number(tgtmode)];
case 14:
return env->banked_r14[r14_bank_number(tgtmode)];
case 8 ... 12:
switch (tgtmode) {
case ARM_CPU_MODE_USR:
return env->usr_regs[regno - 8];
case ARM_CPU_MODE_FIQ:
return env->fiq_regs[regno - 8];
default:
g_assert_not_reached();
}
default:
g_assert_not_reached();
}
}
void HELPER(access_check_cp_reg)(CPUARMState *env, void *rip, uint32_t syndrome,
uint32_t isread)
{
const ARMCPRegInfo *ri = rip;
int target_el;
if (arm_feature(env, ARM_FEATURE_XSCALE) && ri->cp < 14
&& extract32(env->cp15.c15_cpar, ri->cp, 1) == 0) {
raise_exception(env, EXCP_UDEF, syndrome, exception_target_el(env));
}
/*
* Check for an EL2 trap due to HSTR_EL2. We expect EL0 accesses
* to sysregs non accessible at EL0 to have UNDEF-ed already.
*/
if (!is_a64(env) && arm_current_el(env) < 2 && ri->cp == 15 &&
(arm_hcr_el2_eff(env) & (HCR_E2H | HCR_TGE)) != (HCR_E2H | HCR_TGE)) {
uint32_t mask = 1 << ri->crn;
if (ri->type & ARM_CP_64BIT) {
mask = 1 << ri->crm;
}
/* T4 and T14 are RES0 */
mask &= ~((1 << 4) | (1 << 14));
if (env->cp15.hstr_el2 & mask) {
target_el = 2;
goto exept;
}
}
if (!ri->accessfn) {
return;
}
switch (ri->accessfn(env, ri, isread)) {
case CP_ACCESS_OK:
return;
case CP_ACCESS_TRAP:
target_el = exception_target_el(env);
break;
case CP_ACCESS_TRAP_EL2:
/* Requesting a trap to EL2 when we're in EL3 is
* a bug in the access function.
*/
assert(arm_current_el(env) != 3);
target_el = 2;
break;
case CP_ACCESS_TRAP_EL3:
target_el = 3;
break;
case CP_ACCESS_TRAP_UNCATEGORIZED:
target_el = exception_target_el(env);
syndrome = syn_uncategorized();
break;
case CP_ACCESS_TRAP_UNCATEGORIZED_EL2:
target_el = 2;
syndrome = syn_uncategorized();
break;
case CP_ACCESS_TRAP_UNCATEGORIZED_EL3:
target_el = 3;
syndrome = syn_uncategorized();
break;
case CP_ACCESS_TRAP_FP_EL2:
target_el = 2;
/* Since we are an implementation that takes exceptions on a trapped
* conditional insn only if the insn has passed its condition code
* check, we take the IMPDEF choice to always report CV=1 COND=0xe
* (which is also the required value for AArch64 traps).
*/
syndrome = syn_fp_access_trap(1, 0xe, false);
break;
case CP_ACCESS_TRAP_FP_EL3:
target_el = 3;
syndrome = syn_fp_access_trap(1, 0xe, false);
break;
default:
g_assert_not_reached();
}
exept:
raise_exception(env, EXCP_UDEF, syndrome, target_el);
}
void HELPER(set_cp_reg)(CPUARMState *env, void *rip, uint32_t value)
{
const ARMCPRegInfo *ri = rip;
if (ri->type & ARM_CP_IO) {
qemu_mutex_lock_iothread();
ri->writefn(env, ri, value);
qemu_mutex_unlock_iothread();
} else {
ri->writefn(env, ri, value);
}
}
uint32_t HELPER(get_cp_reg)(CPUARMState *env, void *rip)
{
const ARMCPRegInfo *ri = rip;
uint32_t res;
if (ri->type & ARM_CP_IO) {
qemu_mutex_lock_iothread();
res = ri->readfn(env, ri);
qemu_mutex_unlock_iothread();
} else {
res = ri->readfn(env, ri);
}
return res;
}
void HELPER(set_cp_reg64)(CPUARMState *env, void *rip, uint64_t value)
{
const ARMCPRegInfo *ri = rip;
if (ri->type & ARM_CP_IO) {
qemu_mutex_lock_iothread();
ri->writefn(env, ri, value);
qemu_mutex_unlock_iothread();
} else {
ri->writefn(env, ri, value);
}
}
uint64_t HELPER(get_cp_reg64)(CPUARMState *env, void *rip)
{
const ARMCPRegInfo *ri = rip;
uint64_t res;
if (ri->type & ARM_CP_IO) {
qemu_mutex_lock_iothread();
res = ri->readfn(env, ri);
qemu_mutex_unlock_iothread();
} else {
res = ri->readfn(env, ri);
}
return res;
}
void HELPER(pre_hvc)(CPUARMState *env)
{
ARMCPU *cpu = env_archcpu(env);
int cur_el = arm_current_el(env);
/* FIXME: Use actual secure state. */
bool secure = false;
bool undef;
if (arm_is_psci_call(cpu, EXCP_HVC)) {
/* If PSCI is enabled and this looks like a valid PSCI call then
* that overrides the architecturally mandated HVC behaviour.
*/
return;
}
if (!arm_feature(env, ARM_FEATURE_EL2)) {
/* If EL2 doesn't exist, HVC always UNDEFs */
undef = true;
} else if (arm_feature(env, ARM_FEATURE_EL3)) {
/* EL3.HCE has priority over EL2.HCD. */
undef = !(env->cp15.scr_el3 & SCR_HCE);
} else {
undef = env->cp15.hcr_el2 & HCR_HCD;
}
/* In ARMv7 and ARMv8/AArch32, HVC is undef in secure state.
* For ARMv8/AArch64, HVC is allowed in EL3.
* Note that we've already trapped HVC from EL0 at translation
* time.
*/
if (secure && (!is_a64(env) || cur_el == 1)) {
undef = true;
}
if (undef) {
raise_exception(env, EXCP_UDEF, syn_uncategorized(),
exception_target_el(env));
}
}
void HELPER(pre_smc)(CPUARMState *env, uint32_t syndrome)
{
ARMCPU *cpu = env_archcpu(env);
int cur_el = arm_current_el(env);
bool secure = arm_is_secure(env);
bool smd_flag = env->cp15.scr_el3 & SCR_SMD;
/*
* SMC behaviour is summarized in the following table.
* This helper handles the "Trap to EL2" and "Undef insn" cases.
* The "Trap to EL3" and "PSCI call" cases are handled in the exception
* helper.
*
* -> ARM_FEATURE_EL3 and !SMD
* HCR_TSC && NS EL1 !HCR_TSC || !NS EL1
*
* Conduit SMC, valid call Trap to EL2 PSCI Call
* Conduit SMC, inval call Trap to EL2 Trap to EL3
* Conduit not SMC Trap to EL2 Trap to EL3
*
*
* -> ARM_FEATURE_EL3 and SMD
* HCR_TSC && NS EL1 !HCR_TSC || !NS EL1
*
* Conduit SMC, valid call Trap to EL2 PSCI Call
* Conduit SMC, inval call Trap to EL2 Undef insn
* Conduit not SMC Trap to EL2 Undef insn
*
*
* -> !ARM_FEATURE_EL3
* HCR_TSC && NS EL1 !HCR_TSC || !NS EL1
*
* Conduit SMC, valid call Trap to EL2 PSCI Call
* Conduit SMC, inval call Trap to EL2 Undef insn
* Conduit not SMC Undef insn Undef insn
*/
/* On ARMv8 with EL3 AArch64, SMD applies to both S and NS state.
* On ARMv8 with EL3 AArch32, or ARMv7 with the Virtualization
* extensions, SMD only applies to NS state.
* On ARMv7 without the Virtualization extensions, the SMD bit
* doesn't exist, but we forbid the guest to set it to 1 in scr_write(),
* so we need not special case this here.
*/
bool smd = arm_feature(env, ARM_FEATURE_AARCH64) ? smd_flag
: smd_flag && !secure;
if (!arm_feature(env, ARM_FEATURE_EL3) &&
cpu->psci_conduit != QEMU_PSCI_CONDUIT_SMC) {
/* If we have no EL3 then SMC always UNDEFs and can't be
* trapped to EL2. PSCI-via-SMC is a sort of ersatz EL3
* firmware within QEMU, and we want an EL2 guest to be able
* to forbid its EL1 from making PSCI calls into QEMU's
* "firmware" via HCR.TSC, so for these purposes treat
* PSCI-via-SMC as implying an EL3.
* This handles the very last line of the previous table.
*/
raise_exception(env, EXCP_UDEF, syn_uncategorized(),
exception_target_el(env));
}
if (cur_el == 1 && (arm_hcr_el2_eff(env) & HCR_TSC)) {
/* In NS EL1, HCR controlled routing to EL2 has priority over SMD.
* We also want an EL2 guest to be able to forbid its EL1 from
* making PSCI calls into QEMU's "firmware" via HCR.TSC.
* This handles all the "Trap to EL2" cases of the previous table.
*/
raise_exception(env, EXCP_HYP_TRAP, syndrome, 2);
}
/* Catch the two remaining "Undef insn" cases of the previous table:
* - PSCI conduit is SMC but we don't have a valid PCSI call,
* - We don't have EL3 or SMD is set.
*/
if (!arm_is_psci_call(cpu, EXCP_SMC) &&
(smd || !arm_feature(env, ARM_FEATURE_EL3))) {
raise_exception(env, EXCP_UDEF, syn_uncategorized(),
exception_target_el(env));
}
}
/* ??? Flag setting arithmetic is awkward because we need to do comparisons.
The only way to do that in TCG is a conditional branch, which clobbers
all our temporaries. For now implement these as helper functions. */
/* Similarly for variable shift instructions. */
uint32_t HELPER(shl_cc)(CPUARMState *env, uint32_t x, uint32_t i)
{
int shift = i & 0xff;
if (shift >= 32) {
if (shift == 32)
env->CF = x & 1;
else
env->CF = 0;
return 0;
} else if (shift != 0) {
env->CF = (x >> (32 - shift)) & 1;
return x << shift;
}
return x;
}
uint32_t HELPER(shr_cc)(CPUARMState *env, uint32_t x, uint32_t i)
{
int shift = i & 0xff;
if (shift >= 32) {
if (shift == 32)
env->CF = (x >> 31) & 1;
else
env->CF = 0;
return 0;
} else if (shift != 0) {
env->CF = (x >> (shift - 1)) & 1;
return x >> shift;
}
return x;
}
uint32_t HELPER(sar_cc)(CPUARMState *env, uint32_t x, uint32_t i)
{
int shift = i & 0xff;
if (shift >= 32) {
env->CF = (x >> 31) & 1;
return (int32_t)x >> 31;
} else if (shift != 0) {
env->CF = (x >> (shift - 1)) & 1;
return (int32_t)x >> shift;
}
return x;
}
uint32_t HELPER(ror_cc)(CPUARMState *env, uint32_t x, uint32_t i)
{
int shift1, shift;
shift1 = i & 0xff;
shift = shift1 & 0x1f;
if (shift == 0) {
if (shift1 != 0)
env->CF = (x >> 31) & 1;
return x;
} else {
env->CF = (x >> (shift - 1)) & 1;
return ((uint32_t)x >> shift) | (x << (32 - shift));
}
}
void HELPER(probe_access)(CPUARMState *env, target_ulong ptr,
uint32_t access_type, uint32_t mmu_idx,
uint32_t size)
{
uint32_t in_page = -((uint32_t)ptr | TARGET_PAGE_SIZE);
uintptr_t ra = GETPC();
if (likely(size <= in_page)) {
probe_access(env, ptr, size, access_type, mmu_idx, ra);
} else {
probe_access(env, ptr, in_page, access_type, mmu_idx, ra);
probe_access(env, ptr + in_page, size - in_page,
access_type, mmu_idx, ra);
}
}
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