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x86/dumpstack: Remove NULL task pointer convention 

show_stack_log_lvl() and friends allow a NULL pointer for the
task_struct to indicate the current task.  This creates confusion and
can cause sneaky bugs.

Instead require the caller to pass 'current' directly.

This only changes the internal workings of the dumpstack code.  The
dump_trace() and show_stack() interfaces still allow a NULL task
pointer.  Those interfaces should also probably be fixed as well.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf 2016-09-16 08:05:20 -05:00 committed by Ingo Molnar
parent ac496bf48d
commit 81539169f2
4 changed files with 7 additions and 5 deletions
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4
arch/x86/include/asm/stacktrace.h
View File

@ -94,7 +94,7 @@ get_frame_pointer(struct task_struct *task, struct pt_regs *regs)
if (regs)
return (unsigned long *)regs->bp;
if (!task || task == current)
if (task == current)
return __builtin_frame_address(0);
return (unsigned long *)((struct inactive_task_frame *)task->thread.sp)->bp;
@ -113,7 +113,7 @@ get_stack_pointer(struct task_struct *task, struct pt_regs *regs)
if (regs)
return (unsigned long *)kernel_stack_pointer(regs);
if (!task || task == current)
if (task == current)
return __builtin_frame_address(0);
return (unsigned long *)task->thread.sp;

4
arch/x86/kernel/dumpstack.c
View File

@ -175,11 +175,13 @@ void show_stack(struct task_struct *task, unsigned long *sp)
{
unsigned long bp = 0;
task = task ? : current;
/*
* Stack frames below this one aren't interesting. Don't show them
* if we're printing for %current.
*/
if (!sp && (!task || task == current)) {
if (!sp && task == current) {
sp = get_stack_pointer(current, NULL);
bp = (unsigned long)get_frame_pointer(current, NULL);
}

2
arch/x86/kernel/dumpstack_32.c
View File

@ -205,7 +205,7 @@ void show_regs(struct pt_regs *regs)
u8 *ip;
pr_emerg("Stack:\n");
show_stack_log_lvl(NULL, regs, NULL, 0, KERN_EMERG);
show_stack_log_lvl(current, regs, NULL, 0, KERN_EMERG);
pr_emerg("Code:");

2
arch/x86/kernel/dumpstack_64.c
View File

@ -278,7 +278,7 @@ void show_regs(struct pt_regs *regs)
u8 *ip;
printk(KERN_DEFAULT "Stack:\n");
show_stack_log_lvl(NULL, regs, NULL, 0, KERN_DEFAULT);
show_stack_log_lvl(current, regs, NULL, 0, KERN_DEFAULT);
printk(KERN_DEFAULT "Code: ");