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| author | Jiri Slaby <jslaby@suse.cz> | 2013-10-25 17:06:58 +0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-11-13 00:06:06 +0400 |
| commit | 5f01c98859073cb512b01d4fad74b5f4e047be0b (patch) | |
| tree | 57dae13988d5979e69e310049160ed9af1ea14a3 /arch/x86/kernel/process_64.c | |
| parent | 9b66bfb28049594fe2bb2b91607ba302f511ce8b (diff) | |
| download | linux-5f01c98859073cb512b01d4fad74b5f4e047be0b.tar.xz | |
x86/dumpstack: Fix printk_address for direct addresses
Consider a kernel crash in a module, simulated the following way:
static int my_init(void)
{
char *map = (void *)0x5;
*map = 3;
return 0;
}
module_init(my_init);
When we turn off FRAME_POINTERs, the very first instruction in
that function causes a BUG. The problem is that we print IP in
the BUG report using %pB (from printk_address). And %pB
decrements the pointer by one to fix printing addresses of
functions with tail calls.
This was added in commit 71f9e59800e5ad4 ("x86, dumpstack: Use
%pB format specifier for stack trace") to fix the call stack
printouts.
So instead of correct output:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000005
IP: [<ffffffffa01ac000>] my_init+0x0/0x10 [pb173]
We get:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000005
IP: [<ffffffffa0152000>] 0xffffffffa0151fff
To fix that, we use %pS only for stack addresses printouts (via
newly added printk_stack_address) and %pB for regs->ip (via
printk_address). I.e. we revert to the old behaviour for all
except call stacks. And since from all those reliable is 1, we
remove that parameter from printk_address.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: joe@perches.com
Cc: jirislaby@gmail.com
Link: http://lkml.kernel.org/r/1382706418-8435-1-git-send-email-jslaby@suse.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/process_64.c')
| -rw-r--r-- | arch/x86/kernel/process_64.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 45ab4d6fc8a7..176ad94e1d57 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -63,7 +63,7 @@ void __show_regs(struct pt_regs *regs, int all) unsigned int ds, cs, es; printk(KERN_DEFAULT "RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip); - printk_address(regs->ip, 1); + printk_address(regs->ip); printk(KERN_DEFAULT "RSP: %04lx:%016lx EFLAGS: %08lx\n", regs->ss, regs->sp, regs->flags); printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n", |