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systrap/arm64: add the end header after FPSIMD state in signal frame

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gVisor doesn't support other than FPSIMD extension, so we have to be sure that
only FPSIMD states are restored from signal frames. Stub processes are forked
from the sentry and so they can have other extensions such as SVE which shares
FPSR and FPCR registers with FPSIMD.

Fixes #10900

PiperOrigin-RevId: 684878144
This commit is contained in:
Andrei Vagin
2024-10-11 10:22:33 -07:00
committed by gVisor bot
parent 35d3c6eb73
commit f9c7e51064
1 changed files with 12 additions and 5 deletions
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pkg/sentry/platform/systrap/sysmsg/sighandler_arm64.c
+12 -5
View File
@@ -122,16 +122,21 @@ void __export_sighandler(int signo, siginfo_t *siginfo, void *_ucontext) {
// point context.
//
// See: arch/arm64/include/uapi/asm/sigcontext.h
const uint64_t kSigframeMagicHeaderLen = sizeof(struct _aarch64_ctx);
const uint64_t kFpsimdContextSize =
sizeof(struct fpsimd_context) - sizeof(struct _aarch64_ctx);
struct fpsimd_context *fpctx =
(struct fpsimd_context *)&ucontext->uc_mcontext.__reserved;
uint8_t *fpStatePointer = (uint8_t *)&fpctx->fpsr;
// Verify the header.
if (((uint32_t *)&ucontext->uc_mcontext.__reserved)[0] != FPSIMD_MAGIC) {
if (fpctx->head.magic != FPSIMD_MAGIC ||
__export_arch_state.fp_len < kFpsimdContextSize ||
fpctx->head.size != sizeof(struct fpsimd_context)) {
panic(STUB_ERROR_FPSTATE_BAD_HEADER,
((uint32_t *)&ucontext->uc_mcontext.__reserved)[0]);
}
uint8_t *fpStatePointer =
(uint8_t *)&ucontext->uc_mcontext.__reserved + kSigframeMagicHeaderLen;
memcpy(ctx->fpstate, fpStatePointer, __export_arch_state.fp_len);
memcpy(ctx->fpstate, fpStatePointer, kFpsimdContextSize);
ctx->tls = get_tls();
ctx->siginfo = *siginfo;
switch (signo) {
@@ -192,6 +197,8 @@ void restore_state(struct sysmsg *sysmsg, struct thread_context *ctx,
if (atomic_load(&ctx->fpstate_changed)) {
memcpy(fpStatePointer, ctx->fpstate, __export_arch_state.fp_len);
fpctx[1].head.size = 0;
fpctx[1].head.magic = 0;
}
ptregs_to_gregs(ucontext, &ctx->ptregs);
set_tls(ctx->tls);