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accel/tcg/user-exec: Don't parse aarch64 insns to test for read vs write 

In cpu_signal_handler() for aarch64 hosts, currently we parse
the faulting instruction to see if it is a load or a store.
Since the 3.16 kernel (~2014), the kernel has provided us with
the syndrome register for a fault, which includes the WnR bit.
Use this instead if it is present, only falling back to
instruction parsing if not.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190108180014.32386-1-peter.maydell@linaro.org
master
Peter Maydell 2019-01-29 11:46:04 +00:00
parent ea7a5330b7
commit f454a54f3b
1 changed files with 52 additions and 14 deletions
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66
accel/tcg/user-exec.c
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@ -479,28 +479,66 @@ int cpu_signal_handler(int host_signum, void *pinfo,
#elif defined(__aarch64__)
#ifndef ESR_MAGIC
/* Pre-3.16 kernel headers don't have these, so provide fallback definitions */
#define ESR_MAGIC 0x45535201
struct esr_context {
struct _aarch64_ctx head;
uint64_t esr;
};
#endif
static inline struct _aarch64_ctx *first_ctx(ucontext_t *uc)
{
return (struct _aarch64_ctx *)&uc->uc_mcontext.__reserved;
}
static inline struct _aarch64_ctx *next_ctx(struct _aarch64_ctx *hdr)
{
return (struct _aarch64_ctx *)((char *)hdr + hdr->size);
}
int cpu_signal_handler(int host_signum, void *pinfo, void *puc)
{
siginfo_t *info = pinfo;
ucontext_t *uc = puc;
uintptr_t pc = uc->uc_mcontext.pc;
uint32_t insn = *(uint32_t *)pc;
bool is_write;
struct _aarch64_ctx *hdr;
struct esr_context const *esrctx = NULL;
/* XXX: need kernel patch to get write flag faster. */
is_write = ( (insn & 0xbfff0000) == 0x0c000000 /* C3.3.1 */
|| (insn & 0xbfe00000) == 0x0c800000 /* C3.3.2 */
|| (insn & 0xbfdf0000) == 0x0d000000 /* C3.3.3 */
|| (insn & 0xbfc00000) == 0x0d800000 /* C3.3.4 */
|| (insn & 0x3f400000) == 0x08000000 /* C3.3.6 */
|| (insn & 0x3bc00000) == 0x39000000 /* C3.3.13 */
|| (insn & 0x3fc00000) == 0x3d800000 /* ... 128bit */
/* Ingore bits 10, 11 & 21, controlling indexing. */
|| (insn & 0x3bc00000) == 0x38000000 /* C3.3.8-12 */
|| (insn & 0x3fe00000) == 0x3c800000 /* ... 128bit */
/* Ignore bits 23 & 24, controlling indexing. */
|| (insn & 0x3a400000) == 0x28000000); /* C3.3.7,14-16 */
/* Find the esr_context, which has the WnR bit in it */
for (hdr = first_ctx(uc); hdr->magic; hdr = next_ctx(hdr)) {
if (hdr->magic == ESR_MAGIC) {
esrctx = (struct esr_context const *)hdr;
break;
}
}
if (esrctx) {
/* For data aborts ESR.EC is 0b10010x: then bit 6 is the WnR bit */
uint64_t esr = esrctx->esr;
is_write = extract32(esr, 27, 5) == 0x12 && extract32(esr, 6, 1) == 1;
} else {
/*
* Fall back to parsing instructions; will only be needed
* for really ancient (pre-3.16) kernels.
*/
uint32_t insn = *(uint32_t *)pc;
is_write = ((insn & 0xbfff0000) == 0x0c000000 /* C3.3.1 */
|| (insn & 0xbfe00000) == 0x0c800000 /* C3.3.2 */
|| (insn & 0xbfdf0000) == 0x0d000000 /* C3.3.3 */
|| (insn & 0xbfc00000) == 0x0d800000 /* C3.3.4 */
|| (insn & 0x3f400000) == 0x08000000 /* C3.3.6 */
|| (insn & 0x3bc00000) == 0x39000000 /* C3.3.13 */
|| (insn & 0x3fc00000) == 0x3d800000 /* ... 128bit */
/* Ignore bits 10, 11 & 21, controlling indexing. */
|| (insn & 0x3bc00000) == 0x38000000 /* C3.3.8-12 */
|| (insn & 0x3fe00000) == 0x3c800000 /* ... 128bit */
/* Ignore bits 23 & 24, controlling indexing. */
|| (insn & 0x3a400000) == 0x28000000); /* C3.3.7,14-16 */
}
return handle_cpu_signal(pc, info, is_write, &uc->uc_sigmask);
}