[v5] user-only: Cleanup SIGSEGV and SIGBUS handling

[PATCH v5 43/67] hw/core: Add TCGCPUOps.record_sigbus

Richard Henderson posted 67 patches 4 years, 3 months ago

Diff against v6 v7
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Maintainers: Paolo Bonzini <pbonzini@redhat.com>, Taylor Simpson <tsimpson@quicinc.com>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, David Hildenbrand <david@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Greg Kurz <groug@kaod.org>, Cornelia Huck <cohuck@redhat.com>, Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>, Richard Henderson <richard.henderson@linaro.org>, "Philippe Mathieu-Daudé" <f4bug@amsat.org>, Thomas Huth <thuth@redhat.com>, David Gibson <david@gibson.dropbear.id.au>, Artyom Tarasenko <atar4qemu@gmail.com>, Laurent Vivier <laurent@vivier.eu>, Aurelien Jarno <aurelien@aurel32.net>, Eduardo Habkost <ehabkost@redhat.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, Riku Voipio <riku.voipio@iki.fi>, Peter Maydell <peter.maydell@linaro.org>, Yoshinori Sato <ysato@users.sourceforge.jp>, Jiaxun Yang <jiaxun.yang@flygoat.com>, "Philippe Mathieu-Daudé" <philmd@redhat.com>

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[PATCH v5 43/67] hw/core: Add TCGCPUOps.record_sigbus

Posted by Richard Henderson 4 years, 3 months ago

Add a new user-only interface for updating cpu state before
raising a signal.  This will take the place of do_unaligned_access
for user-only and should result in less boilerplate for each guest.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 include/hw/core/tcg-cpu-ops.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/include/hw/core/tcg-cpu-ops.h b/include/hw/core/tcg-cpu-ops.h
index 8eadd404c8..e13898553a 100644
--- a/include/hw/core/tcg-cpu-ops.h
+++ b/include/hw/core/tcg-cpu-ops.h
@@ -135,6 +135,29 @@ struct TCGCPUOps {
     void (*record_sigsegv)(CPUState *cpu, vaddr addr,
                            MMUAccessType access_type,
                            bool maperr, uintptr_t ra);
+    /**
+     * record_sigbus:
+     * @cpu: cpu context
+     * @addr: misaligned guest address
+     * @access_type: access was read/write/execute
+     * @ra: host pc for unwinding
+     *
+     * We are about to raise SIGBUS with si_code BUS_ADRALN,
+     * and si_addr set for @addr.  Record anything further needed
+     * for the signal ucontext_t.
+     *
+     * If the emulated kernel does not provide the signal handler with
+     * anything besides the user context registers, and the siginfo_t,
+     * then this hook need do nothing and may be omitted.
+     * Otherwise, record the data and return; the caller will raise
+     * the signal, unwind the cpu state, and return to the main loop.
+     *
+     * If it is simpler to re-use the sysemu do_unaligned_access code,
+     * @ra is provided so that a "normal" cpu exception can be raised.
+     * In this case, the signal must be raised by the architecture cpu_loop.
+     */
+    void (*record_sigbus)(CPUState *cpu, vaddr addr,
+                          MMUAccessType access_type, uintptr_t ra);
 #endif /* CONFIG_SOFTMMU */
 #endif /* NEED_CPU_H */
 
-- 
2.25.1

Re: [PATCH v5 43/67] hw/core: Add TCGCPUOps.record_sigbus

Posted by Warner Losh 4 years, 3 months ago

On Thu, Oct 14, 2021 at 10:14 PM Richard Henderson <
richard.henderson@linaro.org> wrote:

> Add a new user-only interface for updating cpu state before
> raising a signal.  This will take the place of do_unaligned_access
> for user-only and should result in less boilerplate for each guest.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  include/hw/core/tcg-cpu-ops.h | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
>

Reviewed-by: Warner Losh <imp@bsdimp.com>



> diff --git a/include/hw/core/tcg-cpu-ops.h b/include/hw/core/tcg-cpu-ops.h
> index 8eadd404c8..e13898553a 100644
> --- a/include/hw/core/tcg-cpu-ops.h
> +++ b/include/hw/core/tcg-cpu-ops.h
> @@ -135,6 +135,29 @@ struct TCGCPUOps {
>      void (*record_sigsegv)(CPUState *cpu, vaddr addr,
>                             MMUAccessType access_type,
>                             bool maperr, uintptr_t ra);
> +    /**
> +     * record_sigbus:
> +     * @cpu: cpu context
> +     * @addr: misaligned guest address
> +     * @access_type: access was read/write/execute
> +     * @ra: host pc for unwinding
> +     *
> +     * We are about to raise SIGBUS with si_code BUS_ADRALN,
> +     * and si_addr set for @addr.  Record anything further needed
> +     * for the signal ucontext_t.
> +     *
> +     * If the emulated kernel does not provide the signal handler with
> +     * anything besides the user context registers, and the siginfo_t,
> +     * then this hook need do nothing and may be omitted.
> +     * Otherwise, record the data and return; the caller will raise
> +     * the signal, unwind the cpu state, and return to the main loop.
> +     *
> +     * If it is simpler to re-use the sysemu do_unaligned_access code,
> +     * @ra is provided so that a "normal" cpu exception can be raised.
> +     * In this case, the signal must be raised by the architecture
> cpu_loop.
> +     */
> +    void (*record_sigbus)(CPUState *cpu, vaddr addr,
> +                          MMUAccessType access_type, uintptr_t ra);
>  #endif /* CONFIG_SOFTMMU */
>  #endif /* NEED_CPU_H */
>
> --
> 2.25.1
>
>