On Sun, Jan 11, 2015 at 02:32:30PM +0000, Roman Pen wrote:
> thread_info->syscall is used only for ptrace, but syscall number
> is also used by syscall_get_nr and returned to userspace by the
> following proc file access:
>
> $ cat /proc/self/syscall
> 0 0x3 0xbe928bd8 0x1000 0x0 0xac9e0 0x3 0xbe928bb4 0xb6f5dfbc
> ^
> The first number is the syscall number, currently it is zero.
> Patch fixes this:
>
> $ cat /proc/self/syscall
> 3 0x3 0xbefc7bd8 0x1000 0x0 0xac9e0 0x3 0xbefc7bb4 0xb6e82fbc
> ^
> Right, read syscall
Yes, it seems that despite requiring CONFIG_HAVE_ARCH_TRACEHOOK,
the /proc code requires syscall_get_nr to work regardless of
TIF_SYSCALL_TRACE.
> Signed-off-by: Roman Pen <r.peniaev@xxxxxxxxx>
> Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
> Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
> Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> Cc: Sekhar Nori <nsekhar@xxxxxx>
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> arch/arm/kernel/asm-offsets.c | 1 +
> arch/arm/kernel/entry-common.S | 1 +
> 2 files changed, 2 insertions(+)
>
> diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
> index 2d2d608..6911bad 100644
> --- a/arch/arm/kernel/asm-offsets.c
> +++ b/arch/arm/kernel/asm-offsets.c
> @@ -70,6 +70,7 @@ int main(void)
> DEFINE(TI_CPU, offsetof(struct thread_info, cpu));
> DEFINE(TI_CPU_DOMAIN, offsetof(struct thread_info, cpu_domain));
> DEFINE(TI_CPU_SAVE, offsetof(struct thread_info, cpu_context));
> + DEFINE(TI_SYSCALL, offsetof(struct thread_info, syscall));
> DEFINE(TI_USED_CP, offsetof(struct thread_info, used_cp));
> DEFINE(TI_TP_VALUE, offsetof(struct thread_info, tp_value));
> DEFINE(TI_FPSTATE, offsetof(struct thread_info, fpstate));
> diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
> index f8ccc21..89452ff 100644
> --- a/arch/arm/kernel/entry-common.S
> +++ b/arch/arm/kernel/entry-common.S
> @@ -189,6 +189,7 @@ ENTRY(vector_swi)
> #endif
>
> local_restart:
> + str scno, [tsk, #TI_SYSCALL] @ set syscall number
> ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
> stmdb sp!, {r4, r5} @ push fifth and sixth args
Do we definitely want to update scno on syscall restarting?
Will
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