Skip to content

arm: Add missing hflag update after writing PSTATE #2386

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
phverg wants to merge 2 commits into
base: dev
Choose a base branch
from
+29 −0
Open

arm: Add missing hflag update after writing PSTATE #2386

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
bc27112
target/arm: Rebuild hflags after writing PSTATE
phverg Aug 11, 2026
4adfa6b
tests: Add aarch64 PSTATE hflags rebuild test
phverg Aug 11, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions qemu/target/arm/unicorn_aarch64.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -383,6 +383,7 @@ uc_err reg_write(void *_env, int mode, unsigned int regid, const void *value,
case UC_ARM64_REG_PSTATE:
CHECK_REG_TYPE(uint32_t);
pstate_write(env, *(uint32_t *)value);
arm_rebuild_hflags(env);
break;
case UC_ARM64_REG_TTBR0_EL1:
CHECK_REG_TYPE(uint64_t);
Expand Down
28 changes: 28 additions & 0 deletions tests/unit/test_arm64.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -944,6 +944,32 @@ static void test_arm64_pauth_ctl(void)
OK(uc_close(uc));
}

static void test_arm64_pstate_hflags_rebuild(void)
{
uc_engine *uc;
// mrs x0, currentel
char code[] = "\x40\x42\x38\xd5";
uint64_t x0 = 0, pstate = 0;

uc_common_setup(&uc, UC_ARCH_ARM64, UC_MODE_LITTLE_ENDIAN | UC_MODE_ARM,
code, sizeof(code) - 1, UC_CPU_ARM64_MAX);

// Elevate to EL2 by writing PSTATE. Writing PSTATE must refresh the cached
// hflags, otherwise the current exception level stays stale and MRS
// CurrentEL (as well as a subsequent ERET) observes the old level.
OK(uc_reg_read(uc, UC_ARM64_REG_PSTATE, &pstate));
pstate = (pstate & ~0xcUL) | (2UL << 2); // PSTATE.EL = 2 (EL2)
OK(uc_reg_write(uc, UC_ARM64_REG_PSTATE, &pstate));

OK(uc_emu_start(uc, code_start, code_start + sizeof(code) - 1, 0, 1));

OK(uc_reg_read(uc, UC_ARM64_REG_X0, &x0));
// CurrentEL reports the current EL in bits [3:2]; EL2 -> 0x8.
TEST_CHECK(x0 == 0x8);

OK(uc_close(uc));
}

TEST_LIST = {{"test_arm64_until", test_arm64_until},
{"test_arm64_code_patching", test_arm64_code_patching},
{"test_arm64_code_patching_count", test_arm64_code_patching_count},
Expand All @@ -965,4 +991,6 @@ TEST_LIST = {{"test_arm64_until", test_arm64_until},
{"test_arm64_pc_guarantee", test_arm64_pc_guarantee},
{"test_arm64_pauth_vanilla", test_arm64_pauth_vanilla},
{"test_arm64_pauth_ctl", test_arm64_pauth_ctl},
{"test_arm64_pstate_hflags_rebuild",
test_arm64_pstate_hflags_rebuild},
{NULL, NULL}};