Commit ce5af3ba authored by Jon Medhurst's avatar Jon Medhurst

ARM: kprobes: Add some benchmarking to test module

These benchmarks show the basic speed of kprobes and verify the success
of optimisations done to the emulation of typical function entry
instructions (i.e. push/stmdb).
Signed-off-by: default avatarJon Medhurst <tixy@yxit.co.uk>
Acked-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
parent 963780df
......@@ -185,6 +185,9 @@
#include "kprobes-test.h"
#define BENCHMARKING 1
/*
* Test basic API
*/
......@@ -443,6 +446,157 @@ static int run_api_tests(long (*func)(long, long))
}
/*
* Benchmarking
*/
#if BENCHMARKING
static void __naked benchmark_nop(void)
{
__asm__ __volatile__ (
"nop \n\t"
"bx lr"
);
}
#ifdef CONFIG_THUMB2_KERNEL
#define wide ".w"
#else
#define wide
#endif
static void __naked benchmark_pushpop1(void)
{
__asm__ __volatile__ (
"stmdb"wide" sp!, {r3-r11,lr} \n\t"
"ldmia"wide" sp!, {r3-r11,pc}"
);
}
static void __naked benchmark_pushpop2(void)
{
__asm__ __volatile__ (
"stmdb"wide" sp!, {r0-r8,lr} \n\t"
"ldmia"wide" sp!, {r0-r8,pc}"
);
}
static void __naked benchmark_pushpop3(void)
{
__asm__ __volatile__ (
"stmdb"wide" sp!, {r4,lr} \n\t"
"ldmia"wide" sp!, {r4,pc}"
);
}
static void __naked benchmark_pushpop4(void)
{
__asm__ __volatile__ (
"stmdb"wide" sp!, {r0,lr} \n\t"
"ldmia"wide" sp!, {r0,pc}"
);
}
#ifdef CONFIG_THUMB2_KERNEL
static void __naked benchmark_pushpop_thumb(void)
{
__asm__ __volatile__ (
"push.n {r0-r7,lr} \n\t"
"pop.n {r0-r7,pc}"
);
}
#endif
static int __kprobes
benchmark_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
return 0;
}
static int benchmark(void(*fn)(void))
{
unsigned n, i, t, t0;
for (n = 1000; ; n *= 2) {
t0 = sched_clock();
for (i = n; i > 0; --i)
fn();
t = sched_clock() - t0;
if (t >= 250000000)
break; /* Stop once we took more than 0.25 seconds */
}
return t / n; /* Time for one iteration in nanoseconds */
};
static int kprobe_benchmark(void(*fn)(void), unsigned offset)
{
struct kprobe k = {
.addr = (kprobe_opcode_t *)((uintptr_t)fn + offset),
.pre_handler = benchmark_pre_handler,
};
int ret = register_kprobe(&k);
if (ret < 0) {
pr_err("FAIL: register_kprobe failed with %d\n", ret);
return ret;
}
ret = benchmark(fn);
unregister_kprobe(&k);
return ret;
};
struct benchmarks {
void (*fn)(void);
unsigned offset;
const char *title;
};
static int run_benchmarks(void)
{
int ret;
struct benchmarks list[] = {
{&benchmark_nop, 0, "nop"},
/*
* benchmark_pushpop{1,3} will have the optimised
* instruction emulation, whilst benchmark_pushpop{2,4} will
* be the equivalent unoptimised instructions.
*/
{&benchmark_pushpop1, 0, "stmdb sp!, {r3-r11,lr}"},
{&benchmark_pushpop1, 4, "ldmia sp!, {r3-r11,pc}"},
{&benchmark_pushpop2, 0, "stmdb sp!, {r0-r8,lr}"},
{&benchmark_pushpop2, 4, "ldmia sp!, {r0-r8,pc}"},
{&benchmark_pushpop3, 0, "stmdb sp!, {r4,lr}"},
{&benchmark_pushpop3, 4, "ldmia sp!, {r4,pc}"},
{&benchmark_pushpop4, 0, "stmdb sp!, {r0,lr}"},
{&benchmark_pushpop4, 4, "ldmia sp!, {r0,pc}"},
#ifdef CONFIG_THUMB2_KERNEL
{&benchmark_pushpop_thumb, 0, "push.n {r0-r7,lr}"},
{&benchmark_pushpop_thumb, 2, "pop.n {r0-r7,pc}"},
#endif
{0}
};
struct benchmarks *b;
for (b = list; b->fn; ++b) {
ret = kprobe_benchmark(b->fn, b->offset);
if (ret < 0)
return ret;
pr_info(" %dns for kprobe %s\n", ret, b->title);
}
pr_info("\n");
return 0;
}
#endif /* BENCHMARKING */
/*
* Decoding table self-consistency tests
*/
......@@ -1526,6 +1680,13 @@ static int __init run_all_tests(void)
goto out;
}
#if BENCHMARKING
pr_info("Benchmarks\n");
ret = run_benchmarks();
if (ret)
goto out;
#endif
#if __LINUX_ARM_ARCH__ >= 7
/* We are able to run all test cases so coverage should be complete */
if (coverage_fail) {
......
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