[PATCH v2] linux-user/hppa: Fix segfaults on page zero

[PATCH v2] linux-user/hppa: Fix segfaults on page zero

[Helge Deller]

This program:

    int main(void) { asm("bv %r0(%r0)"); return 0; }

produces on real hppa hardware the expected segfault:

    SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x3} ---
    killed by SIGSEGV +++
    Segmentation fault

But when run on linux-user you get instead internal qemu errors:

ERROR: linux-user/hppa/cpu_loop.c:172:cpu_loop: code should not be reached
Bail out! ERROR: linux-user/hppa/cpu_loop.c:172:cpu_loop: code should not be reached
ERROR: accel/tcg/cpu-exec.c:933:cpu_exec: assertion failed: (cpu == current_cpu)
Bail out! ERROR: accel/tcg/cpu-exec.c:933:cpu_exec: assertion failed: (cpu == current_cpu)

Fix it by adding the missing case for the EXCP_IMP trap in
cpu_loop() and raise a segfault.

Signed-off-by: Helge Deller <deller@gmx.de>
---
Changes:

v2: Dropped the "+++" in the commit message - it confused b4 and git-am.
    no functional changes.

---
diff --git a/linux-user/hppa/cpu_loop.c b/linux-user/hppa/cpu_loop.c
index a576d1a249..8f374aeef6 100644
--- a/linux-user/hppa/cpu_loop.c
+++ b/linux-user/hppa/cpu_loop.c
@@ -143,6 +143,9 @@ void cpu_loop(CPUHPPAState *env)
             env->iaoq_f = env->gr[31];
             env->iaoq_b = env->gr[31] + 4;
             break;
+        case EXCP_IMP:
+            force_sig_fault(TARGET_SIGSEGV, TARGET_SEGV_MAPERR, env->iaoq_f);
+            break;
         case EXCP_ILL:
             force_sig_fault(TARGET_SIGILL, TARGET_ILL_ILLOPN, env->iaoq_f);
             break;

Re: [PATCH v2] linux-user/hppa: Fix segfaults on page zero

[Peter Maydell]

On Mon, 18 Jul 2022 at 17:44, Helge Deller <deller@gmx.de> wrote:
>
> This program:
>
>     int main(void) { asm("bv %r0(%r0)"); return 0; }
>
> produces on real hppa hardware the expected segfault:
>
>     SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x3} ---
>     killed by SIGSEGV +++
>     Segmentation fault
>
> But when run on linux-user you get instead internal qemu errors:
>
> ERROR: linux-user/hppa/cpu_loop.c:172:cpu_loop: code should not be reached
> Bail out! ERROR: linux-user/hppa/cpu_loop.c:172:cpu_loop: code should not be reached
> ERROR: accel/tcg/cpu-exec.c:933:cpu_exec: assertion failed: (cpu == current_cpu)
> Bail out! ERROR: accel/tcg/cpu-exec.c:933:cpu_exec: assertion failed: (cpu == current_cpu)
>
> Fix it by adding the missing case for the EXCP_IMP trap in
> cpu_loop() and raise a segfault.
>
> Signed-off-by: Helge Deller <deller@gmx.de>
> ---
> Changes:
>
> v2: Dropped the "+++" in the commit message - it confused b4 and git-am.
>     no functional changes.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM

Re: [PATCH v2] linux-user/hppa: Fix segfaults on page zero

[Laurent Vivier]

Le 18/07/2022 à 18:40, Helge Deller a écrit :
> This program:
> 
>      int main(void) { asm("bv %r0(%r0)"); return 0; }
> 
> produces on real hppa hardware the expected segfault:
> 
>      SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x3} ---
>      killed by SIGSEGV +++
>      Segmentation fault
> 
> But when run on linux-user you get instead internal qemu errors:
> 
> ERROR: linux-user/hppa/cpu_loop.c:172:cpu_loop: code should not be reached
> Bail out! ERROR: linux-user/hppa/cpu_loop.c:172:cpu_loop: code should not be reached
> ERROR: accel/tcg/cpu-exec.c:933:cpu_exec: assertion failed: (cpu == current_cpu)
> Bail out! ERROR: accel/tcg/cpu-exec.c:933:cpu_exec: assertion failed: (cpu == current_cpu)
> 
> Fix it by adding the missing case for the EXCP_IMP trap in
> cpu_loop() and raise a segfault.
> 
> Signed-off-by: Helge Deller <deller@gmx.de>
> ---
> Changes:
> 
> v2: Dropped the "+++" in the commit message - it confused b4 and git-am.
>      no functional changes.
> 
> ---
> diff --git a/linux-user/hppa/cpu_loop.c b/linux-user/hppa/cpu_loop.c
> index a576d1a249..8f374aeef6 100644
> --- a/linux-user/hppa/cpu_loop.c
> +++ b/linux-user/hppa/cpu_loop.c
> @@ -143,6 +143,9 @@ void cpu_loop(CPUHPPAState *env)
>               env->iaoq_f = env->gr[31];
>               env->iaoq_b = env->gr[31] + 4;
>               break;
> +        case EXCP_IMP:
> +            force_sig_fault(TARGET_SIGSEGV, TARGET_SEGV_MAPERR, env->iaoq_f);
> +            break;
>           case EXCP_ILL:
>               force_sig_fault(TARGET_SIGILL, TARGET_ILL_ILLOPN, env->iaoq_f);
>               break;
> 
> 
> 
Applied to my linux-user-for-7.1 branch.

Thanks,
Laurent