Commit 3737a127 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull more perf updates from Ingo Molnar:
 "A second round of perf updates:

   - wide reaching kprobes sanitization and robustization, with the hope
     of fixing all 'probe this function crashes the kernel' bugs, by
     Masami Hiramatsu.

   - uprobes updates from Oleg Nesterov: tmpfs support, corner case
     fixes and robustization work.

   - perf tooling updates and fixes from Jiri Olsa, Namhyung Ki, Arnaldo
     et al:
        * Add support to accumulate hist periods (Namhyung Kim)
        * various fixes, refactorings and enhancements"

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (101 commits)
  perf: Differentiate exec() and non-exec() comm events
  perf: Fix perf_event_comm() vs. exec() assumption
  uprobes/x86: Rename arch_uprobe->def to ->defparam, minor comment updates
  perf/documentation: Add description for conditional branch filter
  perf/x86: Add conditional branch filtering support
  perf/tool: Add conditional branch filter 'cond' to perf record
  perf: Add new conditional branch filter 'PERF_SAMPLE_BRANCH_COND'
  uprobes: Teach copy_insn() to support tmpfs
  uprobes: Shift ->readpage check from __copy_insn() to uprobe_register()
  perf/x86: Use common PMU interrupt disabled code
  perf/ARM: Use common PMU interrupt disabled code
  perf: Disable sampled events if no PMU interrupt
  perf: Fix use after free in perf_remove_from_context()
  perf tools: Fix 'make help' message error
  perf record: Fix poll return value propagation
  perf tools: Move elide bool into perf_hpp_fmt struct
  perf tools: Remove elide setup for SORT_MODE__MEMORY mode
  perf tools: Fix "==" into "=" in ui_browser__warning assignment
  perf tools: Allow overriding sysfs and proc finding with env var
  perf tools: Consider header files outside perf directory in tags target
  ...
parents c29deef3 82b89778

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/arm/kernel/perf_event.c

+1 −1
Original line number Diff line number Diff line
@@ -410,7 +410,7 @@ __hw_perf_event_init(struct perf_event *event) 
	 */

	hwc->config_base	    |= (unsigned long)mapping;



	if (!hwc->sample_period) {

	if (!is_sampling_event(event)) {

		/*

		 * For non-sampling runs, limit the sample_period to half

		 * of the counter width. That way, the new counter value

arch/arm/kernel/perf_event_cpu.c

+6 −2
Original line number Diff line number Diff line
@@ -126,8 +126,8 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler) 


	irqs = min(pmu_device->num_resources, num_possible_cpus());

	if (irqs < 1) {

		pr_err("no irqs for PMUs defined\n");

		return -ENODEV;

		printk_once("perf/ARM: No irqs for PMU defined, sampling events not supported\n");

		return 0;

	}



	irq = platform_get_irq(pmu_device, 0);
@@ -191,6 +191,10 @@ static void cpu_pmu_init(struct arm_pmu *cpu_pmu) 
	/* Ensure the PMU has sane values out of reset. */

	if (cpu_pmu->reset)

		on_each_cpu(cpu_pmu->reset, cpu_pmu, 1);



	/* If no interrupts available, set the corresponding capability flag */

	if (!platform_get_irq(cpu_pmu->plat_device, 0))

		cpu_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;

}



/*

arch/x86/include/asm/asm.h

+7 −0
Original line number Diff line number Diff line
@@ -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
Original line number Diff line number Diff line
@@ -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 */

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