Re: [PATCH 7/7] powerpc/traps: Show instructions on exceptions
From: LEROY Christophe <hidden>
Date: 2018-07-25 16:01:39
Also in:
lkml
Murilo Opsfelder Araujo [off-list ref] a =C3=A9crit=C2=A0:
Move show_instructions() declaration to arch/powerpc/include/asm/stacktra=
ce.h
and include asm/stracktrace.h in arch/powerpc/kernel/process.c,=20=20 =20which contains the implementation. Modify show_instructions() not to call __kernel_text_address(), allowing userspace instruction dump. probe_kernel_address(), which returns -EFAUL=
T if
something goes wrong, is still being called. Call show_instructions() in arch/powerpc/kernel/traps.c to dump=20=20 =20instructions at faulty location, useful to debugging.
Shouldn't this part be in a second patch ? Wouldn't it be better to also see regs in addition if we want to use=20=20 this=20to understand what happened ? So you could call show_regs() instead of show_instructions() ? Christophe
quoted hunk ↗ jump to hunk
Before this patch, an unhandled signal message looked like: Jul 24 09:57:00 localhost kernel: pandafault[10524]: segfault=20=20 =20(11) at 00000000100007d0 nip 000000001000061c lr 00007fffbd295100=20=20 =20code 2 in pandafault[10000000+10000] After this patch, it looks like: Jul 24 09:57:00 localhost kernel: pandafault[10524]: segfault=20=20 =20(11) at 00000000100007d0 nip 000000001000061c lr 00007fffbd295100=20=20 =20code 2 in pandafault[10000000+10000] Jul 24 09:57:00 localhost kernel: Instruction dump: Jul 24 09:57:00 localhost kernel: 4bfffeec 4bfffee8 3c401002=20=20 =2038427f00 fbe1fff8 f821ffc1 7c3f0b78 3d22fffe Jul 24 09:57:00 localhost kernel: 392988d0 f93f0020 e93f0020=20=20 =2039400048 <99490000> 39200000 7d234b78 383f0040 Signed-off-by: Murilo Opsfelder Araujo <redacted> --- arch/powerpc/include/asm/stacktrace.h | 7 +++++++ arch/powerpc/kernel/process.c | 6 +++--- arch/powerpc/kernel/traps.c | 3 +++ 3 files changed, 13 insertions(+), 3 deletions(-) create mode 100644 arch/powerpc/include/asm/stacktrace.hdiff --git a/arch/powerpc/include/asm/stacktrace.h=20=20=20b/arch/powerpc/include/asm/stacktrace.h new file mode 100644 index 000000000000..46e5ef451578--- /dev/null +++ b/arch/powerpc/include/asm/stacktrace.h@@ -0,0 +1,7 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_POWERPC_STACKTRACE_H +#define _ASM_POWERPC_STACKTRACE_H + +void show_instructions(struct pt_regs *regs); + +#endif /* _ASM_POWERPC_STACKTRACE_H */diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.=
c
quoted hunk ↗ jump to hunk
index b1af3390249c..ee1d63e03c52 100644--- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c@@ -52,6 +52,7 @@ #include <asm/machdep.h> #include <asm/time.h> #include <asm/runlatch.h> +#include <asm/stacktrace.h> #include <asm/syscalls.h> #include <asm/switch_to.h> #include <asm/tm.h>@@ -1261,7 +1262,7 @@ struct task_struct *__switch_to(struct=20=20=20task_struct *prev, static int instructions_to_print =3D 16; -static void show_instructions(struct pt_regs *regs) +void show_instructions(struct pt_regs *regs) { int i; unsigned long pc =3D regs->nip - (instructions_to_print * 3 / 4 *@@ -1283,8 +1284,7 @@ static void show_instructions(struct pt_regs *regs) pc =3D (unsigned long)phys_to_virt(pc); #endif - if (!__kernel_text_address(pc) || - probe_kernel_address((unsigned int __user *)pc, instr)) { + if (probe_kernel_address((unsigned int __user *)pc, instr)) { pr_cont("XXXXXXXX "); } else { if (regs->nip =3D=3D pc)diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index e55ee639d010..3beca17ac1b1 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c@@ -70,6 +70,7 @@ #include <asm/hmi.h> #include <sysdev/fsl_pci.h> #include <asm/kprobes.h> +#include <asm/stacktrace.h> #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC_CORE) int (*__debugger)(struct pt_regs *regs) __read_mostly;@@ -357,6 +358,8 @@ static void show_signal_msg(int signr, struct=20=20=20pt_regs *regs, int code, print_vma_addr(KERN_CONT " in ", regs->nip); pr_cont("\n"); + + show_instructions(regs); } void _exception_pkey(int signr, struct pt_regs *regs, int code, -- 2.17.1