On Tue, 22 Aug 2023 at 18:03, Richard Henderson
<richard.hender...@linaro.org> wrote:
>
> These are all synchronous exceptions for which the kernel
> passes on ESR to the user signal handler.
>
> Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
> @@ -191,6 +199,14 @@ static void target_setup_end_record(struct
> target_aarch64_ctx *end)
> __put_user(0, &end->size);
> }
>
> +static void target_setup_esr_record(struct target_esr_context *esr,
> + CPUARMState *env)
> +{
> + __put_user(TARGET_ESR_MAGIC, &esr->head.magic);
> + __put_user(sizeof(struct target_esr_context), &esr->head.size);
> + __put_user(env->exception.syndrome, &esr->esr);
> +}
> +
> static void target_setup_sve_record(struct target_sve_context *sve,
> CPUARMState *env, int size)
> {
> @@ -443,6 +459,10 @@ static int target_restore_sigframe(CPUARMState *env,
> fpsimd = (struct target_fpsimd_context *)ctx;
> break;
>
> + case TARGET_ESR_MAGIC:
> + /* ignore */
> + break;
> +
> case TARGET_SVE_MAGIC:
> if (sve || size < sizeof(struct target_sve_context)) {
> goto err;
> @@ -558,6 +578,23 @@ static int alloc_sigframe_space(int this_size,
> target_sigframe_layout *l)
> return this_loc;
> }
>
> +static bool need_save_esr(target_siginfo_t *info, CPUARMState *env)
> +{
> + int sig = info->si_signo;
> + int type = info->si_code >> 16;
> +
> + if (type != QEMU_SI_FAULT) {
> + return false;
> + }
> +
> + /* See arch/arm64/mm/fault.c, set_thread_esr. */
> + if (sig == TARGET_SIGSEGV || sig == TARGET_SIGBUS) {
> + return true;
> + }
It's possible to get here without env->exception.syndrome
being set correctly, I think, if we take a host
SIGSEGV or SIGBUS and host_signal_handler() calls either
cpu_loop_exit_sigsegv() or cpu_loop_exit_sigbus(). Can also
happen for other places that call one of those two functions,
like allocation_tag_mem(). At least, I can't see where we
would be setting syndrome in that code path.
> +
> + return false;
> +}
Maybe we should do the "sanitize ESR for fault addresses in
the upper half of guest address space" logic that the kernel
set_thread_esr() does?
thanks
-- PMM
