Commit 7ceb3a10 authored by Mark Rutland's avatar Mark Rutland Committed by Catalin Marinas
Browse files

arm64: simplify dump_mem 



Currently dump_mem attempts to dump memory in 64-bit chunks when
reporting a failure in 64-bit code, or 32-bit chunks when reporting a
failure in 32-bit code. We added code to handle these two cases
separately in commit e147ae6d ("arm64: modify the dump mem for
64 bit addresses").

However, in all cases dump_mem is called, the failing context is a
kernel rather than user context. Additionally dump_mem is assumed to
only be used for kernel contexts, as internally it switches to
KERNEL_DS, and its callers pass kernel stack bounds.

This patch removes the redundant 32-bit chunk logic and associated
compat parameter, largely reverting the aforementioned commit. For the
call in __die(), the check of in_interrupt() is removed also, as __die()
is only called in response to faults from the kernel's exception level,
and thus the !user_mode(regs) check is sufficient. Were this not the
case, the used of task_stack_page(tsk) to generate the stack bounds
would be erroneous.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent bffe1baf

arch/arm64/kernel/traps.c

+11 −20
Original line number Diff line number Diff line
@@ -52,15 +52,14 @@ static const char *handler[]= { 
int show_unhandled_signals = 1;



/*

 * Dump out the contents of some memory nicely...

 * Dump out the contents of some kernel memory nicely...

 */

static void dump_mem(const char *lvl, const char *str, unsigned long bottom,

		     unsigned long top, bool compat)

		     unsigned long top)

{

	unsigned long first;

	mm_segment_t fs;

	int i;

	unsigned int width = compat ? 4 : 8;



	/*

	 * We need to switch to kernel mode so that we can use __get_user
@@ -78,22 +77,15 @@ static void dump_mem(const char *lvl, const char *str, unsigned long bottom, 
		memset(str, ' ', sizeof(str));

		str[sizeof(str) - 1] = '\0';



		for (p = first, i = 0; i < (32 / width)

					&& p < top; i++, p += width) {

		for (p = first, i = 0; i < (32 / 8)

					&& p < top; i++, p += 8) {

			if (p >= bottom && p < top) {

				unsigned long val;



				if (width == 8) {

				if (__get_user(val, (unsigned long *)p) == 0)

					sprintf(str + i * 17, " %016lx", val);

				else

					sprintf(str + i * 17, " ????????????????");

				} else {

					if (__get_user(val, (unsigned int *)p) == 0)

						sprintf(str + i * 9, " %08lx", val);

					else

						sprintf(str + i * 9, " ????????");

				}

			}

		}

		printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
@@ -216,7 +208,7 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk) 
				stack = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);



			dump_mem("", "Exception stack", stack,

				 stack + sizeof(struct pt_regs), false);

				 stack + sizeof(struct pt_regs));

		}

	}

}
@@ -254,10 +246,9 @@ static int __die(const char *str, int err, struct thread_info *thread, 
	pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",

		 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);



	if (!user_mode(regs) || in_interrupt()) {

	if (!user_mode(regs)) {

		dump_mem(KERN_EMERG, "Stack: ", regs->sp,

			 THREAD_SIZE + (unsigned long)task_stack_page(tsk),

			 compat_user_mode(regs));

			 THREAD_SIZE + (unsigned long)task_stack_page(tsk));

		dump_backtrace(regs, tsk);

		dump_instr(KERN_EMERG, regs);

	}

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