* [PATCH 1/1] dumpstack: fix printk_address for direct addresses
@ 2013-10-12 20:13 Jiri Slaby
2013-10-12 21:35 ` Joe Perches
0 siblings, 1 reply; 3+ messages in thread
From: Jiri Slaby @ 2013-10-12 20:13 UTC (permalink / raw)
To: x86
Cc: jirislaby, linux-kernel, Jiri Slaby, Namhyung Kim,
Frederic Weisbecker, Ingo Molnar, H. Peter Anvin, Thomas Gleixner
Consider modules like this:
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 71f9e59800e5ad4e6b683348424c9fe54306cd43 (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: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/include/asm/kdebug.h | 2 +-
arch/x86/kernel/dumpstack.c | 11 ++++++++---
arch/x86/kernel/process_64.c | 2 +-
arch/x86/mm/fault.c | 2 +-
arch/x86/platform/uv/uv_nmi.c | 2 +-
5 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/arch/x86/include/asm/kdebug.h b/arch/x86/include/asm/kdebug.h
index 2c37aad..32ce713 100644
--- a/arch/x86/include/asm/kdebug.h
+++ b/arch/x86/include/asm/kdebug.h
@@ -21,7 +21,7 @@ enum die_val {
DIE_NMIUNKNOWN,
};
-extern void printk_address(unsigned long address, int reliable);
+extern void printk_address(unsigned long address);
extern void die(const char *, struct pt_regs *,long);
extern int __must_check __die(const char *, struct pt_regs *, long);
extern void show_trace(struct task_struct *t, struct pt_regs *regs,
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index deb6421..d9c12d3 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -25,12 +25,17 @@ unsigned int code_bytes = 64;
int kstack_depth_to_print = 3 * STACKSLOTS_PER_LINE;
static int die_counter;
-void printk_address(unsigned long address, int reliable)
+static void printk_stack_address(unsigned long address, int reliable)
{
pr_cont(" [<%p>] %s%pB\n",
(void *)address, reliable ? "" : "? ", (void *)address);
}
+void printk_address(unsigned long address)
+{
+ pr_cont(" [<%p>] %pS\n", (void *)address, (void *)address);
+}
+
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static void
print_ftrace_graph_addr(unsigned long addr, void *data,
@@ -151,7 +156,7 @@ static void print_trace_address(void *data, unsigned long addr, int reliable)
{
touch_nmi_watchdog();
printk(data);
- printk_address(addr, reliable);
+ printk_stack_address(addr, reliable);
}
static const struct stacktrace_ops print_trace_ops = {
@@ -281,7 +286,7 @@ int __kprobes __die(const char *str, struct pt_regs *regs, long err)
#else
/* Executive summary in case the oops scrolled away */
printk(KERN_ALERT "RIP ");
- printk_address(regs->ip, 1);
+ printk_address(regs->ip);
printk(" RSP <%016lx>\n", regs->sp);
#endif
return 0;
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 45ab4d6..176ad94 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",
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 3aaeffc..18feeb3 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -596,7 +596,7 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code,
printk(KERN_CONT " at %p\n", (void *) address);
printk(KERN_ALERT "IP:");
- printk_address(regs->ip, 1);
+ printk_address(regs->ip);
dump_pagetable(address);
}
diff --git a/arch/x86/platform/uv/uv_nmi.c b/arch/x86/platform/uv/uv_nmi.c
index 9126dfb..019b6ec 100644
--- a/arch/x86/platform/uv/uv_nmi.c
+++ b/arch/x86/platform/uv/uv_nmi.c
@@ -402,7 +402,7 @@ static void uv_nmi_dump_cpu_ip(int cpu, struct pt_regs *regs)
printk(KERN_DEFAULT "UV: %4d %6d %-32.32s ",
cpu, current->pid, current->comm);
- printk_address(regs->ip, 1);
+ printk_address(regs->ip);
}
/* Dump this cpu's state */
--
1.8.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 1/1] dumpstack: fix printk_address for direct addresses
2013-10-12 20:13 [PATCH 1/1] dumpstack: fix printk_address for direct addresses Jiri Slaby
@ 2013-10-12 21:35 ` Joe Perches
2013-10-16 9:52 ` Jiri Slaby
0 siblings, 1 reply; 3+ messages in thread
From: Joe Perches @ 2013-10-12 21:35 UTC (permalink / raw)
To: Jiri Slaby, Jiri Kosina
Cc: x86, jirislaby, linux-kernel, Namhyung Kim, Frederic Weisbecker,
Ingo Molnar, H. Peter Anvin, Thomas Gleixner
On Sat, 2013-10-12 at 22:13 +0200, Jiri Slaby wrote:
[]
> 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.
I'm still waiting for you to apply this:
https://lkml.org/lkml/2013/7/22/701
https://lkml.org/lkml/2013/7/22/700
Oh wait, wrong Jiri... ;-)
Anyway, I'd rather your specific changes be done inline
so it's less possible to have interleaved messages.
> diff --git a/arch/x86/include/asm/kdebug.h b/arch/x86/include/asm/kdebug.h
[]
> @@ -21,7 +21,7 @@ enum die_val {
> DIE_NMIUNKNOWN,
> };
>
> -extern void printk_address(unsigned long address, int reliable);
> +extern void printk_address(unsigned long address);
I think this can be removed.
> diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
[]
> @@ -25,12 +25,17 @@ unsigned int code_bytes = 64;
> int kstack_depth_to_print = 3 * STACKSLOTS_PER_LINE;
> static int die_counter;
>
> -void printk_address(unsigned long address, int reliable)
> +static void printk_stack_address(unsigned long address, int reliable)
> {
> pr_cont(" [<%p>] %s%pB\n",
> (void *)address, reliable ? "" : "? ", (void *)address);
> }
This is now used only once and could/should be done
at the single use site.
> +void printk_address(unsigned long address)
> +{
> + pr_cont(" [<%p>] %pS\n", (void *)address, (void *)address);
> +}
> +
And this could/should be done inline in the few
places it's used.
> #ifdef CONFIG_FUNCTION_GRAPH_TRACER
> static void
> print_ftrace_graph_addr(unsigned long addr, void *data,
> @@ -151,7 +156,7 @@ static void print_trace_address(void *data, unsigned long addr, int reliable)
> {
> touch_nmi_watchdog();
> printk(data);
> - printk_address(addr, reliable);
> + printk_stack_address(addr, reliable);
printk("%s [<%p>] %s%pB\n",
data, (void *)addr, reliable ? "" : "? ", (void *)addr);
> @@ -281,7 +286,7 @@ int __kprobes __die(const char *str, struct pt_regs *regs, long err)
> #else
> /* Executive summary in case the oops scrolled away */
> printk(KERN_ALERT "RIP ");
> - printk_address(regs->ip, 1);
> + printk_address(regs->ip);
printk(KERN_ALERT "RIP [<%p>] %pS\n",
(void *)regs->ip, (void *)regs->ip);
> diff --git 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 "RIP: %04lx:[<%016lx>] [<%p>] %pS\n",
regs->cs & 0xffff, regs->ip,
(void *)regs->ip, (void *)regs->ip);
This one looks ugly to me.
It emits the address twice.
> 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",
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index 3aaeffc..18feeb3 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -596,7 +596,7 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code,
>
> printk(KERN_CONT " at %p\n", (void *) address);
> printk(KERN_ALERT "IP:");
> - printk_address(regs->ip, 1);
> + printk_address(regs->ip);
printk(KERN_ALERT "IP: [<%p>] %pS\n",
(void *)regs->ip, (void *)regs->ip);
> dump_pagetable(address);
> }
> diff --git a/arch/x86/platform/uv/uv_nmi.c b/arch/x86/platform/uv/uv_nmi.c
> index 9126dfb..019b6ec 100644
> --- a/arch/x86/platform/uv/uv_nmi.c
> +++ b/arch/x86/platform/uv/uv_nmi.c
> @@ -402,7 +402,7 @@ static void uv_nmi_dump_cpu_ip(int cpu, struct pt_regs *regs)
> printk(KERN_DEFAULT "UV: %4d %6d %-32.32s ",
> cpu, current->pid, current->comm);
>
> - printk_address(regs->ip, 1);
> + printk_address(regs->ip);
printk(KERN_DEFAULT "UV: %4d %6d %-32.32s [<%p>] %pS\n",
cpu, current->pid, current->comm,
(void *)regs->ip, (void *)regs->ip);
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 1/1] dumpstack: fix printk_address for direct addresses
2013-10-12 21:35 ` Joe Perches
@ 2013-10-16 9:52 ` Jiri Slaby
0 siblings, 0 replies; 3+ messages in thread
From: Jiri Slaby @ 2013-10-16 9:52 UTC (permalink / raw)
To: Joe Perches, Jiri Kosina
Cc: x86, jirislaby, linux-kernel, Namhyung Kim, Frederic Weisbecker,
Ingo Molnar, H. Peter Anvin, Thomas Gleixner
On 10/12/2013 11:35 PM, Joe Perches wrote:
> On Sat, 2013-10-12 at 22:13 +0200, Jiri Slaby wrote:
> []
>> 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.
>
> I'm still waiting for you to apply this:
>
> https://lkml.org/lkml/2013/7/22/701
> https://lkml.org/lkml/2013/7/22/700
>
> Oh wait, wrong Jiri... ;-)
>
> Anyway, I'd rather your specific changes be done inline
> so it's less possible to have interleaved messages.
Why you are putting this here?
>> diff --git a/arch/x86/include/asm/kdebug.h b/arch/x86/include/asm/kdebug.h
> []
>> @@ -21,7 +21,7 @@ enum die_val {
>> DIE_NMIUNKNOWN,
>> };
>>
>> -extern void printk_address(unsigned long address, int reliable);
>> +extern void printk_address(unsigned long address);
>
> I think this can be removed.
I'm waiting for an x86's guys input as to what do they prefer to be done?
>> diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
> []
>> @@ -25,12 +25,17 @@ unsigned int code_bytes = 64;
>> int kstack_depth_to_print = 3 * STACKSLOTS_PER_LINE;
>> static int die_counter;
>>
>> -void printk_address(unsigned long address, int reliable)
>> +static void printk_stack_address(unsigned long address, int reliable)
>> {
>> pr_cont(" [<%p>] %s%pB\n",
>> (void *)address, reliable ? "" : "? ", (void *)address);
>> }
>
> This is now used only once and could/should be done
> at the single use site.
>
>> +void printk_address(unsigned long address)
>> +{
>> + pr_cont(" [<%p>] %pS\n", (void *)address, (void *)address);
>> +}
>> +
>
> And this could/should be done inline in the few
> places it's used.
>
>> #ifdef CONFIG_FUNCTION_GRAPH_TRACER
>> static void
>> print_ftrace_graph_addr(unsigned long addr, void *data,
>> @@ -151,7 +156,7 @@ static void print_trace_address(void *data, unsigned long addr, int reliable)
>> {
>> touch_nmi_watchdog();
>> printk(data);
>> - printk_address(addr, reliable);
>> + printk_stack_address(addr, reliable);
>
> printk("%s [<%p>] %s%pB\n",
> data, (void *)addr, reliable ? "" : "? ", (void *)addr);
>
>> @@ -281,7 +286,7 @@ int __kprobes __die(const char *str, struct pt_regs *regs, long err)
>> #else
>> /* Executive summary in case the oops scrolled away */
>> printk(KERN_ALERT "RIP ");
>> - printk_address(regs->ip, 1);
>> + printk_address(regs->ip);
>
> printk(KERN_ALERT "RIP [<%p>] %pS\n",
> (void *)regs->ip, (void *)regs->ip);
>
>> diff --git 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 "RIP: %04lx:[<%016lx>] [<%p>] %pS\n",
> regs->cs & 0xffff, regs->ip,
> (void *)regs->ip, (void *)regs->ip);
>
> This one looks ugly to me.
> It emits the address twice.
>
>> 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",
>> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
>> index 3aaeffc..18feeb3 100644
>> --- a/arch/x86/mm/fault.c
>> +++ b/arch/x86/mm/fault.c
>> @@ -596,7 +596,7 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code,
>>
>> printk(KERN_CONT " at %p\n", (void *) address);
>> printk(KERN_ALERT "IP:");
>> - printk_address(regs->ip, 1);
>> + printk_address(regs->ip);
>
> printk(KERN_ALERT "IP: [<%p>] %pS\n",
> (void *)regs->ip, (void *)regs->ip);
>
>> dump_pagetable(address);
>> }
>> diff --git a/arch/x86/platform/uv/uv_nmi.c b/arch/x86/platform/uv/uv_nmi.c
>> index 9126dfb..019b6ec 100644
>> --- a/arch/x86/platform/uv/uv_nmi.c
>> +++ b/arch/x86/platform/uv/uv_nmi.c
>> @@ -402,7 +402,7 @@ static void uv_nmi_dump_cpu_ip(int cpu, struct pt_regs *regs)
>> printk(KERN_DEFAULT "UV: %4d %6d %-32.32s ",
>> cpu, current->pid, current->comm);
>>
>> - printk_address(regs->ip, 1);
>> + printk_address(regs->ip);
>
> printk(KERN_DEFAULT "UV: %4d %6d %-32.32s [<%p>] %pS\n",
> cpu, current->pid, current->comm,
> (void *)regs->ip, (void *)regs->ip);
>
>
--
js
suse labs
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2013-10-16 9:52 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-10-12 20:13 [PATCH 1/1] dumpstack: fix printk_address for direct addresses Jiri Slaby
2013-10-12 21:35 ` Joe Perches
2013-10-16 9:52 ` Jiri Slaby
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox