[PATCH -v2 1/3] x86/dumpstack: Honor supplied @regs arg

From: Borislav Petkov
Date: Mon Jul 04 2016 - 18:31:50 EST


From: Andy Lutomirski <luto@xxxxxxxxxx>

The comment suggests that show_stack(NULL, NULL) should backtrace the
current context, but the code doesn't match the comment. If regs are
given, start the "Stack:" hexdump at regs->sp.

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: x86-ml <x86@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/efcd79bf4106d61f1cd258c2caa87f3a0618eeac.1466036668.git.luto@xxxxxxxxxx
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
arch/x86/kernel/dumpstack_32.c | 4 +++-
arch/x86/kernel/dumpstack_64.c | 4 +++-
2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index fef917e79b9d..948d77da3881 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -96,7 +96,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
int i;

if (sp == NULL) {
- if (task)
+ if (regs)
+ sp = (unsigned long *)regs->sp;
+ else if (task)
sp = (unsigned long *)task->thread.sp;
else
sp = (unsigned long *)&sp;
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index d558a8a49016..a81e1ef73bf2 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -264,7 +264,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
* back trace for this cpu:
*/
if (sp == NULL) {
- if (task)
+ if (regs)
+ sp = (unsigned long *)regs->sp;
+ else if (task)
sp = (unsigned long *)task->thread.sp;
else
sp = (unsigned long *)&sp;
--
2.7.3