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SubjectRe: [PATCH v4 5/6] powerpc: Add show_user_instructions()
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Le 01/08/2018 à 23:33, Murilo Opsfelder Araujo a écrit :
> show_user_instructions() is a slightly modified version of
> show_instructions() that allows userspace instruction dump.
>
> This will be useful within show_signal_msg() to dump userspace
> instructions of the faulty location.
>
> Here is a sample of what show_user_instructions() outputs:
>
> pandafault[10850]: code: 4bfffeec 4bfffee8 3c401002 38427f00 fbe1fff8 f821ffc1 7c3f0b78 3d22fffe
> pandafault[10850]: code: 392988d0 f93f0020 e93f0020 39400048 <99490000> 39200000 7d234b78 383f0040
>
> The current->comm and current->pid printed can serve as a glue that
> links the instructions dump to its originator, allowing messages to be
> interleaved in the logs.
>
> Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
> ---
> arch/powerpc/include/asm/stacktrace.h | 13 +++++++++
> arch/powerpc/kernel/process.c | 40 +++++++++++++++++++++++++++
> 2 files changed, 53 insertions(+)
> create mode 100644 arch/powerpc/include/asm/stacktrace.h
>
> diff --git a/arch/powerpc/include/asm/stacktrace.h b/arch/powerpc/include/asm/stacktrace.h
> new file mode 100644
> index 000000000000..6149b53b3bc8
> --- /dev/null
> +++ b/arch/powerpc/include/asm/stacktrace.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Stack trace functions.
> + *
> + * Copyright 2018, Murilo Opsfelder Araujo, IBM Corporation.
> + */
> +
> +#ifndef _ASM_POWERPC_STACKTRACE_H
> +#define _ASM_POWERPC_STACKTRACE_H
> +
> +void show_user_instructions(struct pt_regs *regs);
> +
> +#endif /* _ASM_POWERPC_STACKTRACE_H */
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index e9533b4d2f08..364645ac732c 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1299,6 +1299,46 @@ static void show_instructions(struct pt_regs *regs)
> pr_cont("\n");
> }
>
> +void show_user_instructions(struct pt_regs *regs)
> +{
> + int i;
> + const char *prefix = KERN_INFO "%s[%d]: code: ";
> + unsigned long pc = regs->nip - (instructions_to_print * 3 / 4 *
> + sizeof(int));
> +
> + printk(prefix, current->comm, current->pid);

Why not use pr_info() and remove KERN_INFO from *prefix ?

> +
> + for (i = 0; i < instructions_to_print; i++) {
> + int instr;
> +
> + if (!(i % 8) && (i > 0)) {
> + pr_cont("\n");
> + printk(prefix, current->comm, current->pid);
> + }
> +
> +#if !defined(CONFIG_BOOKE)
> + /* If executing with the IMMU off, adjust pc rather
> + * than print XXXXXXXX.
> + */
> + if (!(regs->msr & MSR_IR))
> + pc = (unsigned long)phys_to_virt(pc);

Shouldn't this be done outside of the loop, only once ?

Christophe

> +#endif
> +
> + if (probe_kernel_address((unsigned int __user *)pc, instr)) {
> + pr_cont("XXXXXXXX ");
> + } else {
> + if (regs->nip == pc)
> + pr_cont("<%08x> ", instr);
> + else
> + pr_cont("%08x ", instr);
> + }
> +
> + pc += sizeof(int);
> + }
> +
> + pr_cont("\n");
> +}
> +
> struct regbit {
> unsigned long bit;
> const char *name;
>

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