Commit f7667ca1 authored by Max Filippov's avatar Max Filippov
Browse files

xtensa: dump userspace code around the exception PC 



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

Signed-off-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
parent cc34f290

arch/xtensa/Kconfig.debug

+8 −0
Original line number Diff line number Diff line
@@ -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.

arch/xtensa/kernel/traps.c

+18 −0
Original line number Diff line number Diff line
@@ -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);

}