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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 e147ae6d7f ("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: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Mark Rutland 2016-06-13 11:15:15 +01:00 committed by Catalin Marinas
parent bffe1baff5
commit 7ceb3a1040
1 changed files with 11 additions and 20 deletions
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31
arch/arm64/kernel/traps.c
View File

@ -52,15 +52,14 @@ static const char *handler[]= {
int show_unhandled_signals = 1; 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, static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
unsigned long top, bool compat) unsigned long top)
{ {
unsigned long first; unsigned long first;
mm_segment_t fs; mm_segment_t fs;
int i; int i;
unsigned int width = compat ? 4 : 8;
/* /*
* We need to switch to kernel mode so that we can use __get_user * 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)); memset(str, ' ', sizeof(str));
str[sizeof(str) - 1] = '\0'; str[sizeof(str) - 1] = '\0';
for (p = first, i = 0; i < (32 / width) for (p = first, i = 0; i < (32 / 8)
&& p < top; i++, p += width) { && p < top; i++, p += 8) {
if (p >= bottom && p < top) { if (p >= bottom && p < top) {
unsigned long val; unsigned long val;
if (width == 8) { if (__get_user(val, (unsigned long *)p) == 0)
if (__get_user(val, (unsigned long *)p) == 0) sprintf(str + i * 17, " %016lx", val);
sprintf(str + i * 17, " %016lx", val); else
else sprintf(str + i * 17, " ????????????????");
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); 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); stack = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
dump_mem("", "Exception stack", stack, 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", pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1); 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, dump_mem(KERN_EMERG, "Stack: ", regs->sp,
THREAD_SIZE + (unsigned long)task_stack_page(tsk), THREAD_SIZE + (unsigned long)task_stack_page(tsk));
compat_user_mode(regs));
dump_backtrace(regs, tsk); dump_backtrace(regs, tsk);
dump_instr(KERN_EMERG, regs); dump_instr(KERN_EMERG, regs);
} }