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accel/tcg: Preserve PAGE_ANON when changing page permissions

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Using mprotect() to change PROT_* does not change the MAP_ANON
previously set with mmap().  Our linux-user version of MTE only
works with MAP_ANON pages, so losing PAGE_ANON caused MTE to
stop working.

Reported-by: Stephen Long <steplong@quicinc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Richard Henderson 2021-04-06 10:40:20 -07:00 committed by Peter Maydell
parent 017a913af4
commit eb42297a59
4 changed files with 53 additions and 4 deletions
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9
accel/tcg/translate-all.c
View file

@ -2714,6 +2714,8 @@ void page_set_flags(target_ulong start, target_ulong end, int flags)
a missing call to h2g_valid. */
assert(end - 1 <= GUEST_ADDR_MAX);
assert(start < end);
/* Only set PAGE_ANON with new mappings. */
assert(!(flags & PAGE_ANON) || (flags & PAGE_RESET));
assert_memory_lock();
start = start & TARGET_PAGE_MASK;
@ -2737,11 +2739,14 @@ void page_set_flags(target_ulong start, target_ulong end, int flags)
p->first_tb) {
tb_invalidate_phys_page(addr, 0);
}
if (reset_target_data && p->target_data) {
if (reset_target_data) {
g_free(p->target_data);
p->target_data = NULL;
p->flags = flags;
} else {
/* Using mprotect on a page does not change MAP_ANON. */
p->flags = (p->flags & PAGE_ANON) | flags;
}
p->flags = flags;
}
}

2
tests/tcg/aarch64/Makefile.target
View file

@ -37,7 +37,7 @@ AARCH64_TESTS += bti-2
# MTE Tests
ifneq ($(DOCKER_IMAGE)$(CROSS_CC_HAS_ARMV8_MTE),)
AARCH64_TESTS += mte-1 mte-2 mte-3 mte-4
AARCH64_TESTS += mte-1 mte-2 mte-3 mte-4 mte-6
mte-%: CFLAGS += -march=armv8.5-a+memtag
endif

43
tests/tcg/aarch64/mte-6.c Normal file
View file

@ -0,0 +1,43 @@
#include "mte.h"
void pass(int sig, siginfo_t *info, void *uc)
{
assert(info->si_code == SEGV_MTESERR);
exit(0);
}
int main(void)
{
enable_mte(PR_MTE_TCF_SYNC);
void *brk = sbrk(16);
if (brk == (void *)-1) {
perror("sbrk");
return 2;
}
if (mprotect(brk, 16, PROT_READ | PROT_WRITE | PROT_MTE)) {
perror("mprotect");
return 2;
}
int *p1, *p2;
long excl = 1;
asm("irg %0,%1,%2" : "=r"(p1) : "r"(brk), "r"(excl));
asm("gmi %0,%1,%0" : "+r"(excl) : "r"(p1));
asm("irg %0,%1,%2" : "=r"(p2) : "r"(brk), "r"(excl));
asm("stg %0,[%0]" : : "r"(p1));
*p1 = 0;
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = pass;
sa.sa_flags = SA_SIGINFO;
sigaction(SIGSEGV, &sa, NULL);
*p2 = 0;
abort();
}

3
tests/tcg/aarch64/mte.h
View file

@ -48,7 +48,8 @@ static void enable_mte(int tcf)
}
}
static void *alloc_mte_mem(size_t size)
static void * alloc_mte_mem(size_t size) __attribute__((unused));
static void * alloc_mte_mem(size_t size)
{
void *p = mmap(NULL, size, PROT_READ | PROT_WRITE | PROT_MTE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);