From 4f5c67f8df7f26e559509c68c45e652709edd23f Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Wed, 22 Mar 2023 08:00:27 -0700 Subject: [PATCH] linux-user/arm: Take more care allocating commpage MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit User setting of -R reserved_va can lead to an assertion failure in page_set_flags. Sanity check the value of reserved_va and print an error message instead. Do not allocate a commpage at all for m-profile cpus. Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Richard Henderson --- linux-user/elfload.c | 37 +++++++++++++++++++++++++++---------- 1 file changed, 27 insertions(+), 10 deletions(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index f1370a7a8b..b96b3e566b 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -423,12 +423,32 @@ enum { static bool init_guest_commpage(void) { - abi_ptr commpage = HI_COMMPAGE & -qemu_host_page_size; - void *want = g2h_untagged(commpage); - void *addr = mmap(want, qemu_host_page_size, PROT_READ | PROT_WRITE, - MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0); + ARMCPU *cpu = ARM_CPU(thread_cpu); + abi_ptr want = HI_COMMPAGE & TARGET_PAGE_MASK; + abi_ptr addr; - if (addr == MAP_FAILED) { + /* + * M-profile allocates maximum of 2GB address space, so can never + * allocate the commpage. Skip it. + */ + if (arm_feature(&cpu->env, ARM_FEATURE_M)) { + return true; + } + + /* + * If reserved_va does not cover the commpage, we get an assert + * in page_set_flags. Produce an intelligent error instead. + */ + if (reserved_va != 0 && want + TARGET_PAGE_SIZE - 1 > reserved_va) { + error_report("Allocating guest commpage: -R 0x%" PRIx64 " too small", + (uint64_t)reserved_va + 1); + exit(EXIT_FAILURE); + } + + addr = target_mmap(want, TARGET_PAGE_SIZE, PROT_READ | PROT_WRITE, + MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0); + + if (addr == -1) { perror("Allocating guest commpage"); exit(EXIT_FAILURE); } @@ -437,15 +457,12 @@ static bool init_guest_commpage(void) } /* Set kernel helper versions; rest of page is 0. */ - __put_user(5, (uint32_t *)g2h_untagged(0xffff0ffcu)); + put_user_u32(5, 0xffff0ffcu); - if (mprotect(addr, qemu_host_page_size, PROT_READ)) { + if (target_mprotect(addr, qemu_host_page_size, PROT_READ | PROT_EXEC)) { perror("Protecting guest commpage"); exit(EXIT_FAILURE); } - - page_set_flags(commpage, commpage | ~qemu_host_page_mask, - PAGE_READ | PAGE_EXEC | PAGE_VALID); return true; }