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Commit 4d7d8c82 authored by Chuck Ebbert's avatar Chuck Ebbert Committed by Linus Torvalds
Browse files

[PATCH] i386: multi-column stack backtraces 



Print stack backtraces in multiple columns, saving screen space.  Number of
columns is configurable and defaults to one so behavior is
backwards-compatible.

Also removes the brackets around addresses when printing more
that one entry per line so they print as:
    <address>
instead of:
    [<address>]
This helps multiple entries fit better on one line.

Original idea by Dave Jones, taken from x86_64.

Signed-off-by: default avatarChuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: default avatarDave Jones <davej@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent b824eb60

arch/i386/Kconfig.debug

+9 −0
Original line number Diff line number Diff line
@@ -31,6 +31,15 @@ config DEBUG_STACK_USAGE 


	  This option will slow down process creation somewhat.



config STACK_BACKTRACE_COLS

	int "Stack backtraces per line" if DEBUG_KERNEL

	range 1 3

	default 2

	help

	  Selects how many stack backtrace entries per line to display.



	  This can save screen space when displaying traces.



comment "Page alloc debug is incompatible with Software Suspend on i386"

	depends on DEBUG_KERNEL && SOFTWARE_SUSPEND

arch/i386/kernel/traps.c

+27 −5
Original line number Diff line number Diff line
@@ -112,12 +112,30 @@ static inline int valid_stack_ptr(struct thread_info *tinfo, void *p) 
		p < (void *)tinfo + THREAD_SIZE - 3;

}



static void print_addr_and_symbol(unsigned long addr, char *log_lvl)

/*

 * Print CONFIG_STACK_BACKTRACE_COLS address/symbol entries per line.

 */

static inline int print_addr_and_symbol(unsigned long addr, char *log_lvl,

					int printed)

{

	if (!printed)

		printk(log_lvl);



#if CONFIG_STACK_BACKTRACE_COLS == 1

	printk(" [<%08lx>] ", addr);

#else

	printk(" <%08lx> ", addr);

#endif

	print_symbol("%s", addr);



	printed = (printed + 1) % CONFIG_STACK_BACKTRACE_COLS;



	if (printed)

		printk("  ");

	else

		printk("\n");



	return printed;

}



static inline unsigned long print_context_stack(struct thread_info *tinfo,
@@ -125,20 +143,24 @@ static inline unsigned long print_context_stack(struct thread_info *tinfo, 
				char *log_lvl)

{

	unsigned long addr;

	int printed = 0; /* nr of entries already printed on current line */



#ifdef	CONFIG_FRAME_POINTER

	while (valid_stack_ptr(tinfo, (void *)ebp)) {

		addr = *(unsigned long *)(ebp + 4);

		print_addr_and_symbol(addr, log_lvl);

		printed = print_addr_and_symbol(addr, log_lvl, printed);

		ebp = *(unsigned long *)ebp;

	}

#else

	while (valid_stack_ptr(tinfo, stack)) {

		addr = *stack++;

		if (__kernel_text_address(addr))

			print_addr_and_symbol(addr, log_lvl);

			printed = print_addr_and_symbol(addr, log_lvl, printed);

	}

#endif

	if (printed)

		printk("\n");



	return ebp;

}