linux-kernel - Re: [PATCH 1/1] dumpstack: fix printk

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Date:	Sat, 12 Oct 2013 14:35:10 -0700
From:	Joe Perches <joe@...ches.com>
To:	Jiri Slaby <jslaby@...e.cz>, Jiri Kosina <trivial@...nel.org>
Cc:	x86@...nel.org, jirislaby@...il.com, linux-kernel@...r.kernel.org,
	Namhyung Kim <namhyung@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1/1] dumpstack: fix printk_address for direct addresses

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);


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