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Message-ID: <tip-cfeeed279dc2fa83a00fbe4856ebd231d56201ab@git.kernel.org>
Date: Wed, 14 Sep 2016 10:39:55 -0700
From: tip-bot for Josh Poimboeuf <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: luto@...nel.org, dvlasenk@...hat.com, luto@...capital.net,
linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
brgerst@...il.com, hpa@...or.com, rostedt@...dmis.org,
tglx@...utronix.de, fweisbec@...il.com, nilayvaish@...il.com,
peterz@...radead.org, bp@...en8.de, byungchul.park@....com,
mingo@...nel.org, keescook@...omium.org, jpoimboe@...hat.com
Subject: [tip:x86/asm] x86/dumpstack: Allow preemption in
show_stack_log_lvl() and dump_trace()
Commit-ID: cfeeed279dc2fa83a00fbe4856ebd231d56201ab
Gitweb: http://git.kernel.org/tip/cfeeed279dc2fa83a00fbe4856ebd231d56201ab
Author: Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate: Thu, 8 Sep 2016 16:49:20 -0500
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 14 Sep 2016 17:23:30 +0200
x86/dumpstack: Allow preemption in show_stack_log_lvl() and dump_trace()
show_stack_log_lvl() and dump_trace() are already preemption safe:
- If they're running in irq or exception context, preemption is already
disabled and the percpu stack pointers can be trusted.
- If they're running with preemption enabled, they must be running on
the task stack anyway, so it doesn't matter if they're comparing the
stack pointer against a percpu stack pointer from this CPU or another
one: either way it won't match.
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Byungchul Park <byungchul.park@....com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Nilay Vaish <nilayvaish@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/a0ca0b1044eca97d4f0ec7c1619cf80b3b65560d.1473371307.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
arch/x86/kernel/dumpstack_32.c | 14 ++++++--------
arch/x86/kernel/dumpstack_64.c | 26 +++++++++-----------------
2 files changed, 15 insertions(+), 25 deletions(-)
diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index c533b8b..da5cd62 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -24,16 +24,16 @@ static void *is_irq_stack(void *p, void *irq)
}
-static void *is_hardirq_stack(unsigned long *stack, int cpu)
+static void *is_hardirq_stack(unsigned long *stack)
{
- void *irq = per_cpu(hardirq_stack, cpu);
+ void *irq = this_cpu_read(hardirq_stack);
return is_irq_stack(stack, irq);
}
-static void *is_softirq_stack(unsigned long *stack, int cpu)
+static void *is_softirq_stack(unsigned long *stack)
{
- void *irq = per_cpu(softirq_stack, cpu);
+ void *irq = this_cpu_read(softirq_stack);
return is_irq_stack(stack, irq);
}
@@ -42,7 +42,6 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
unsigned long *stack, unsigned long bp,
const struct stacktrace_ops *ops, void *data)
{
- const unsigned cpu = get_cpu();
int graph = 0;
u32 *prev_esp;
@@ -53,9 +52,9 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
for (;;) {
void *end_stack;
- end_stack = is_hardirq_stack(stack, cpu);
+ end_stack = is_hardirq_stack(stack);
if (!end_stack)
- end_stack = is_softirq_stack(stack, cpu);
+ end_stack = is_softirq_stack(stack);
bp = ops->walk_stack(task, stack, bp, ops, data,
end_stack, &graph);
@@ -74,7 +73,6 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
break;
touch_nmi_watchdog();
}
- put_cpu();
}
EXPORT_SYMBOL(dump_trace);
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index b243352..07373be 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -31,8 +31,8 @@ static char x86_stack_ids[][8] = {
#endif
};
-static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
- unsigned *usedp, char **idp)
+static unsigned long *in_exception_stack(unsigned long stack, unsigned *usedp,
+ char **idp)
{
unsigned k;
@@ -41,7 +41,7 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
* 'stack' is in one of them:
*/
for (k = 0; k < N_EXCEPTION_STACKS; k++) {
- unsigned long end = per_cpu(orig_ist, cpu).ist[k];
+ unsigned long end = raw_cpu_ptr(&orig_ist)->ist[k];
/*
* Is 'stack' above this exception frame's end?
* If yes then skip to the next frame.
@@ -111,7 +111,7 @@ enum stack_type {
};
static enum stack_type
-analyze_stack(int cpu, struct task_struct *task, unsigned long *stack,
+analyze_stack(struct task_struct *task, unsigned long *stack,
unsigned long **stack_end, unsigned long *irq_stack,
unsigned *used, char **id)
{
@@ -121,8 +121,7 @@ analyze_stack(int cpu, struct task_struct *task, unsigned long *stack,
if ((unsigned long)task_stack_page(task) == addr)
return STACK_IS_NORMAL;
- *stack_end = in_exception_stack(cpu, (unsigned long)stack,
- used, id);
+ *stack_end = in_exception_stack((unsigned long)stack, used, id);
if (*stack_end)
return STACK_IS_EXCEPTION;
@@ -149,8 +148,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
unsigned long *stack, unsigned long bp,
const struct stacktrace_ops *ops, void *data)
{
- const unsigned cpu = get_cpu();
- unsigned long *irq_stack = (unsigned long *)per_cpu(irq_stack_ptr, cpu);
+ unsigned long *irq_stack = (unsigned long *)this_cpu_read(irq_stack_ptr);
unsigned used = 0;
int graph = 0;
int done = 0;
@@ -169,8 +167,8 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
enum stack_type stype;
char *id;
- stype = analyze_stack(cpu, task, stack, &stack_end,
- irq_stack, &used, &id);
+ stype = analyze_stack(task, stack, &stack_end, irq_stack, &used,
+ &id);
/* Default finish unless specified to continue */
done = 1;
@@ -225,7 +223,6 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
* This handles the process stack:
*/
bp = ops->walk_stack(task, stack, bp, ops, data, NULL, &graph);
- put_cpu();
}
EXPORT_SYMBOL(dump_trace);
@@ -236,13 +233,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
unsigned long *irq_stack_end;
unsigned long *irq_stack;
unsigned long *stack;
- int cpu;
int i;
- preempt_disable();
- cpu = smp_processor_id();
-
- irq_stack_end = (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
+ irq_stack_end = (unsigned long *)this_cpu_read(irq_stack_ptr);
irq_stack = irq_stack_end - (IRQ_STACK_SIZE / sizeof(long));
sp = sp ? : get_stack_pointer(task, regs);
@@ -274,7 +267,6 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
stack++;
touch_nmi_watchdog();
}
- preempt_enable();
pr_cont("\n");
show_trace_log_lvl(task, regs, sp, bp, log_lvl);
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