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Commit 0f46efeb authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Ingo Molnar
Browse files

kprobes, x86: Prohibit probing on debug_stack_*() 



Prohibit probing on debug_stack_reset and debug_stack_set_zero.
Since the both functions are called from TRACE_IRQS_ON/OFF_DEBUG
macros which run in int3 ist entry, probing it may cause a soft
lockup.

This happens when the kernel built with CONFIG_DYNAMIC_FTRACE=y
and CONFIG_TRACE_IRQFLAGS=y.

Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Link: http://lkml.kernel.org/r/20140417081712.26341.32994.stgit@ltc230.yrl.intra.hitachi.co.jp


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 376e2424

arch/x86/kernel/cpu/common.c

+4 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <linux/delay.h>

#include <linux/sched.h>

#include <linux/init.h>

#include <linux/kprobes.h>

#include <linux/kgdb.h>

#include <linux/smp.h>

#include <linux/io.h>
@@ -1160,6 +1161,7 @@ int is_debug_stack(unsigned long addr) 
		(addr <= __get_cpu_var(debug_stack_addr) &&

		 addr > (__get_cpu_var(debug_stack_addr) - DEBUG_STKSZ));

}

NOKPROBE_SYMBOL(is_debug_stack);



DEFINE_PER_CPU(u32, debug_idt_ctr);
@@ -1168,6 +1170,7 @@ void debug_stack_set_zero(void) 
	this_cpu_inc(debug_idt_ctr);

	load_current_idt();

}

NOKPROBE_SYMBOL(debug_stack_set_zero);



void debug_stack_reset(void)

{
@@ -1176,6 +1179,7 @@ void debug_stack_reset(void) 
	if (this_cpu_dec_return(debug_idt_ctr) == 0)

		load_current_idt();

}

NOKPROBE_SYMBOL(debug_stack_reset);



#else	/* CONFIG_X86_64 */