Commit 10b02564 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

Merge branch 'perf/kprobes' into perf/core 



Conflicts:
	arch/x86/kernel/traps.c

The kprobes enhancements are fully cooked, ship them upstream.

Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parents c56d3406 69902c71

Documentation/kprobes.txt

+15 −1
Original line number Diff line number Diff line
@@ -22,8 +22,9 @@ Appendix B: The kprobes sysctl interface 


Kprobes enables you to dynamically break into any kernel routine and

collect debugging and performance information non-disruptively. You

can trap at almost any kernel code address, specifying a handler

can trap at almost any kernel code address(*), specifying a handler

routine to be invoked when the breakpoint is hit.

(*: some parts of the kernel code can not be trapped, see 1.5 Blacklist)



There are currently three types of probes: kprobes, jprobes, and

kretprobes (also called return probes).  A kprobe can be inserted
@@ -273,6 +274,19 @@ using one of the following techniques: 
 or

- Execute 'sysctl -w debug.kprobes_optimization=n'



1.5 Blacklist



Kprobes can probe most of the kernel except itself. This means

that there are some functions where kprobes cannot probe. Probing

(trapping) such functions can cause a recursive trap (e.g. double

fault) or the nested probe handler may never be called.

Kprobes manages such functions as a blacklist.

If you want to add a function into the blacklist, you just need

to (1) include linux/kprobes.h and (2) use NOKPROBE_SYMBOL() macro

to specify a blacklisted function.

Kprobes checks the given probe address against the blacklist and

rejects registering it, if the given address is in the blacklist.



2. Architectures Supported



Kprobes, jprobes, and return probes are implemented on the following

arch/x86/include/asm/asm.h

+7 −0
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@@ -57,6 +57,12 @@ 
	.long (from) - . ;					\

	.long (to) - . + 0x7ffffff0 ;				\

	.popsection



# define _ASM_NOKPROBE(entry)					\

	.pushsection "_kprobe_blacklist","aw" ;			\

	_ASM_ALIGN ;						\

	_ASM_PTR (entry);					\

	.popsection

#else

# define _ASM_EXTABLE(from,to)					\

	" .pushsection \"__ex_table\",\"a\"\n"			\
@@ -71,6 +77,7 @@ 
	" .long (" #from ") - .\n"				\

	" .long (" #to ") - . + 0x7ffffff0\n"			\

	" .popsection\n"

/* For C file, we already have NOKPROBE_SYMBOL macro */

#endif



#endif /* _ASM_X86_ASM_H */

arch/x86/include/asm/kprobes.h

+2 −0
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@@ -116,4 +116,6 @@ struct kprobe_ctlblk { 
extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr);

extern int kprobe_exceptions_notify(struct notifier_block *self,

				    unsigned long val, void *data);

extern int kprobe_int3_handler(struct pt_regs *regs);

extern int kprobe_debug_handler(struct pt_regs *regs);

#endif /* _ASM_X86_KPROBES_H */

arch/x86/include/asm/traps.h

+1 −1
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@@ -68,7 +68,7 @@ dotraplinkage void do_segment_not_present(struct pt_regs *, long); 
dotraplinkage void do_stack_segment(struct pt_regs *, long);

#ifdef CONFIG_X86_64

dotraplinkage void do_double_fault(struct pt_regs *, long);

asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *);

asmlinkage struct pt_regs *sync_regs(struct pt_regs *);

#endif

dotraplinkage void do_general_protection(struct pt_regs *, long);

dotraplinkage void do_page_fault(struct pt_regs *, unsigned long);

arch/x86/kernel/alternative.c

+1 −2
Original line number Diff line number Diff line
@@ -5,7 +5,6 @@ 
#include <linux/mutex.h>

#include <linux/list.h>

#include <linux/stringify.h>

#include <linux/kprobes.h>

#include <linux/mm.h>

#include <linux/vmalloc.h>

#include <linux/memory.h>
@@ -551,7 +550,7 @@ void *__init_or_module text_poke_early(void *addr, const void *opcode, 
 *

 * Note: Must be called under text_mutex.

 */

void *__kprobes text_poke(void *addr, const void *opcode, size_t len)

void *text_poke(void *addr, const void *opcode, size_t len)

{

	unsigned long flags;

	char *vaddr;