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powerpc: Add show_user_instructions()

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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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Murilo Opsfelder Araujo 2018-08-01 18:33:19 -03:00 committed by Michael Ellerman
parent 0f642d616b
commit 88b0fe1757
2 changed files with 45 additions and 0 deletions
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13
arch/powerpc/include/asm/stacktrace.h Normal file
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@ -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 */

32
arch/powerpc/kernel/process.c
View File

@ -1299,6 +1299,38 @@ static void show_instructions(struct pt_regs *regs)
pr_cont("\n");
}
void show_user_instructions(struct pt_regs *regs)
{
unsigned long pc;
int i;
pc = regs->nip - (instructions_to_print * 3 / 4 * sizeof(int));
pr_info("%s[%d]: code: ", current->comm, current->pid);
for (i = 0; i < instructions_to_print; i++) {
int instr;
if (!(i % 8) && (i > 0)) {
pr_cont("\n");
pr_info("%s[%d]: code: ", current->comm, current->pid);
}
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;