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xtensa: dump userspace code around the exception PC

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In the absence of other debug facilities dumping user code around the
unhandled exception address may help debugging the issue.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
This commit is contained in:
Max Filippov 2023-05-07 16:18:17 -07:00
parent cc34f2909d
commit f7667ca106
2 changed files with 26 additions and 0 deletions
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8
arch/xtensa/Kconfig.debug
View file

@ -38,3 +38,11 @@ config PRINT_STACK_DEPTH
help
This option allows you to set the stack depth that the kernel
prints in stack traces.
config PRINT_USER_CODE_ON_UNHANDLED_EXCEPTION
bool "Dump user code around unhandled exception address"
help
Enable this option to display user code around PC of the unhandled
exception (starting at address aligned on 16 byte boundary).
This may simplify finding faulting code in the absence of other
debug facilities.

18
arch/xtensa/kernel/traps.c
View file

@ -175,6 +175,23 @@ __die_if_kernel(const char *str, struct pt_regs *regs, long err)
die(str, regs, err);
}
#ifdef CONFIG_PRINT_USER_CODE_ON_UNHANDLED_EXCEPTION
static inline void dump_user_code(struct pt_regs *regs)
{
char buf[32];
if (copy_from_user(buf, (void __user *)(regs->pc & -16), sizeof(buf)) == 0) {
print_hex_dump(KERN_INFO, " ", DUMP_PREFIX_NONE,
32, 1, buf, sizeof(buf), false);
}
}
#else
static inline void dump_user_code(struct pt_regs *regs)
{
}
#endif
/*
* Unhandled Exceptions. Kill user task or panic if in kernel space.
*/
@ -190,6 +207,7 @@ void do_unhandled(struct pt_regs *regs)
"\tEXCCAUSE is %ld\n",
current->comm, task_pid_nr(current), regs->pc,
regs->exccause);
dump_user_code(regs);
force_sig(SIGILL);
}