From bbb7d4925a05ecd5bbfdbc1147d402b0db203a5a Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Mon, 16 Nov 2015 12:10:14 +0000 Subject: [PATCH] perf test: Test the BPF prologue adding infrastructure This patch introduces a new BPF script to test the BPF prologue adding routines. The new script probes at null_lseek, which is the function pointer used when we try to lseek on '/dev/null'. The null_lseek function is chosen because it is used by function pointers, so we don't need to consider inlining and LTO. By extracting file->f_mode, bpf-script-test-prologue.c should know whether the file is writable or readonly. According to llseek_loop() and bpf-script-test-prologue.c, one fourth of total lseeks should be collected. Committer note: Testing it: # perf test -v BPF Kernel build dir is set to /lib/modules/4.3.0+/build set env: KBUILD_DIR=/lib/modules/4.3.0+/build unset env: KBUILD_OPTS include option is set to -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.9.2/include -I/home/git/linux/arch/x86/include -Iarch/x86/include/generated/uapi -Iarch/x86/include/generated -I/home/git/linux/include -Iinclude -I/home/git/linux/arch/x86/include/uapi -Iarch/x86/include/generated/uapi -I/home/git/linux/include/uapi -Iinclude/generated/uapi -include /home/git/linux/include/linux/kconfig.h set env: NR_CPUS=4 set env: LINUX_VERSION_CODE=0x40300 set env: CLANG_EXEC=/usr/libexec/icecc/bin/clang set env: CLANG_OPTIONS=-xc set env: KERNEL_INC_OPTIONS= -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/4.9.2/include -I/home/git/linux/arch/x86/include -Iarch/x86/include/generated/uapi -Iarch/x86/include/generated -I/home/git/linux/include -Iinclude -I/home/git/linux/arch/x86/include/uapi -Iarch/x86/include/generated/uapi -I/home/git/linux/include/uapi -Iinclude/generated/uapi -include /home/git/linux/include/linux/kconfig.h set env: WORKING_DIR=/lib/modules/4.3.0+/build set env: CLANG_SOURCE=- llvm compiling command template: echo '/* * bpf-script-test-prologue.c * Test BPF prologue */ #ifndef LINUX_VERSION_CODE # error Need LINUX_VERSION_CODE # error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig' #endif #define SEC(NAME) __attribute__((section(NAME), used)) #include #define FMODE_READ 0x1 #define FMODE_WRITE 0x2 static void (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) = (void *) 6; SEC("func=null_lseek file->f_mode offset orig") int bpf_func__null_lseek(void *ctx, int err, unsigned long f_mode, unsigned long offset, unsigned long orig) { if (err) return 0; if (f_mode & FMODE_WRITE) return 0; if (offset & 1) return 0; if (orig == SEEK_CUR) return 0; return 1; } char _license[] SEC("license") = "GPL"; int _version SEC("version") = LINUX_VERSION_CODE; ' | $CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS -DLINUX_VERSION_CODE=$LINUX_VERSION_CODE $CLANG_OPTIONS $KERNEL_INC_OPTIONS -Wno-unused-value -Wno-pointer-sign -working-directory $WORKING_DIR -c "$CLANG_SOURCE" -target bpf -O2 -o - libbpf: loading object '[bpf_prologue_test]' from buffer libbpf: section .strtab, size 135, link 0, flags 0, type=3 libbpf: section .text, size 0, link 0, flags 6, type=1 libbpf: section .data, size 0, link 0, flags 3, type=1 libbpf: section .bss, size 0, link 0, flags 3, type=8 libbpf: section func=null_lseek file->f_mode offset orig, size 112, link 0, flags 6, type=1 libbpf: found program func=null_lseek file->f_mode offset orig libbpf: section license, size 4, link 0, flags 3, type=1 libbpf: license of [bpf_prologue_test] is GPL libbpf: section version, size 4, link 0, flags 3, type=1 libbpf: kernel version of [bpf_prologue_test] is 40300 libbpf: section .symtab, size 168, link 1, flags 0, type=2 bpf: config program 'func=null_lseek file->f_mode offset orig' symbol:null_lseek file:(null) line:0 offset:0 return:0 lazy:(null) parsing arg: file->f_mode into file, f_mode(1) parsing arg: offset into offset parsing arg: orig into orig bpf: config 'func=null_lseek file->f_mode offset orig' is ok Looking at the vmlinux_path (7 entries long) Using /lib/modules/4.3.0+/build/vmlinux for symbols Open Debuginfo file: /lib/modules/4.3.0+/build/vmlinux Try to find probe point from debuginfo. Matched function: null_lseek Probe point found: null_lseek+0 Searching 'file' variable in context. Converting variable file into trace event. converting f_mode in file f_mode type is unsigned int. Searching 'offset' variable in context. Converting variable offset into trace event. offset type is long long int. Searching 'orig' variable in context. Converting variable orig into trace event. orig type is int. Found 1 probe_trace_events. Opening /sys/kernel/debug/tracing//kprobe_events write=1 Writing event: p:perf_bpf_probe/func _text+4840528 f_mode=+68(%di):u32 offset=%si:s64 orig=%dx:s32 libbpf: don't need create maps for [bpf_prologue_test] prologue: pass validation prologue: slow path prologue: fetch arg 0, base reg is %di prologue: arg 0: offset 68 prologue: fetch arg 1, base reg is %si prologue: fetch arg 2, base reg is %dx add bpf event perf_bpf_probe:func and attach bpf program 3 adding perf_bpf_probe:func adding perf_bpf_probe:func to 0x51672c0 mmap size 1052672B Opening /sys/kernel/debug/tracing//kprobe_events write=1 Opening /sys/kernel/debug/tracing//uprobe_events write=1 Parsing probe_events: p:perf_bpf_probe/func _text+4840528 f_mode=+68(%di):u32 offset=%si:s64 orig=%dx:s32 Group:perf_bpf_probe Event:func probe:p Writing event: -:perf_bpf_probe/func test child finished with 0 ---- end ---- Test BPF filter: Ok # Signed-off-by: Wang Nan Tested-by: Arnaldo Carvalho de Melo Cc: Alexei Starovoitov Cc: Masami Hiramatsu Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1447675815-166222-13-git-send-email-wangnan0@huawei.com [ Added tools/perf/tests/llvm-src-prologue.c to .gitignore ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/tests/.gitignore | 1 + tools/perf/tests/Build | 9 +++++- tools/perf/tests/bpf-script-test-prologue.c | 35 +++++++++++++++++++++ tools/perf/tests/bpf.c | 34 ++++++++++++++++++++ tools/perf/tests/llvm.c | 4 +++ tools/perf/tests/llvm.h | 2 ++ 6 files changed, 84 insertions(+), 1 deletion(-) create mode 100644 tools/perf/tests/bpf-script-test-prologue.c diff --git a/tools/perf/tests/.gitignore b/tools/perf/tests/.gitignore index 489fc9ffbcb0..bf016c439fbd 100644 --- a/tools/perf/tests/.gitignore +++ b/tools/perf/tests/.gitignore @@ -1,2 +1,3 @@ llvm-src-base.c llvm-src-kbuild.c +llvm-src-prologue.c diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build index f41ebf8849fe..0ff8a973b81c 100644 --- a/tools/perf/tests/Build +++ b/tools/perf/tests/Build @@ -31,7 +31,7 @@ perf-y += sample-parsing.o perf-y += parse-no-sample-id-all.o perf-y += kmod-path.o perf-y += thread-map.o -perf-y += llvm.o llvm-src-base.o llvm-src-kbuild.o +perf-y += llvm.o llvm-src-base.o llvm-src-kbuild.o llvm-src-prologue.o perf-y += bpf.o perf-y += topology.o @@ -49,6 +49,13 @@ $(OUTPUT)tests/llvm-src-kbuild.c: tests/bpf-script-test-kbuild.c $(Q)sed -e 's/"/\\"/g' -e 's/\(.*\)/"\1\\n"/g' $< >> $@ $(Q)echo ';' >> $@ +$(OUTPUT)tests/llvm-src-prologue.c: tests/bpf-script-test-prologue.c + $(call rule_mkdir) + $(Q)echo '#include ' > $@ + $(Q)echo 'const char test_llvm__bpf_test_prologue_prog[] =' >> $@ + $(Q)sed -e 's/"/\\"/g' -e 's/\(.*\)/"\1\\n"/g' $< >> $@ + $(Q)echo ';' >> $@ + ifeq ($(ARCH),$(filter $(ARCH),x86 arm arm64)) perf-$(CONFIG_DWARF_UNWIND) += dwarf-unwind.o endif diff --git a/tools/perf/tests/bpf-script-test-prologue.c b/tools/perf/tests/bpf-script-test-prologue.c new file mode 100644 index 000000000000..7230e62c70fc --- /dev/null +++ b/tools/perf/tests/bpf-script-test-prologue.c @@ -0,0 +1,35 @@ +/* + * bpf-script-test-prologue.c + * Test BPF prologue + */ +#ifndef LINUX_VERSION_CODE +# error Need LINUX_VERSION_CODE +# error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig' +#endif +#define SEC(NAME) __attribute__((section(NAME), used)) + +#include + +#define FMODE_READ 0x1 +#define FMODE_WRITE 0x2 + +static void (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) = + (void *) 6; + +SEC("func=null_lseek file->f_mode offset orig") +int bpf_func__null_lseek(void *ctx, int err, unsigned long f_mode, + unsigned long offset, unsigned long orig) +{ + if (err) + return 0; + if (f_mode & FMODE_WRITE) + return 0; + if (offset & 1) + return 0; + if (orig == SEEK_CUR) + return 0; + return 1; +} + +char _license[] SEC("license") = "GPL"; +int _version SEC("version") = LINUX_VERSION_CODE; diff --git a/tools/perf/tests/bpf.c b/tools/perf/tests/bpf.c index 6ebfdee3e2c6..d58442294e9e 100644 --- a/tools/perf/tests/bpf.c +++ b/tools/perf/tests/bpf.c @@ -19,6 +19,29 @@ static int epoll_pwait_loop(void) return 0; } +#ifdef HAVE_BPF_PROLOGUE + +static int llseek_loop(void) +{ + int fds[2], i; + + fds[0] = open("/dev/null", O_RDONLY); + fds[1] = open("/dev/null", O_RDWR); + + if (fds[0] < 0 || fds[1] < 0) + return -1; + + for (i = 0; i < NR_ITERS; i++) { + lseek(fds[i % 2], i, (i / 2) % 2 ? SEEK_CUR : SEEK_SET); + lseek(fds[(i + 1) % 2], i, (i / 2) % 2 ? SEEK_CUR : SEEK_SET); + } + close(fds[0]); + close(fds[1]); + return 0; +} + +#endif + static struct { enum test_llvm__testcase prog_id; const char *desc; @@ -37,6 +60,17 @@ static struct { &epoll_pwait_loop, (NR_ITERS + 1) / 2, }, +#ifdef HAVE_BPF_PROLOGUE + { + LLVM_TESTCASE_BPF_PROLOGUE, + "Test BPF prologue generation", + "[bpf_prologue_test]", + "fix kbuild first", + "check your vmlinux setting?", + &llseek_loop, + (NR_ITERS + 1) / 4, + }, +#endif }; static int do_test(struct bpf_object *obj, int (*func)(void), diff --git a/tools/perf/tests/llvm.c b/tools/perf/tests/llvm.c index 366e38ba8b49..b4147634fb44 100644 --- a/tools/perf/tests/llvm.c +++ b/tools/perf/tests/llvm.c @@ -44,6 +44,10 @@ static struct { .source = test_llvm__bpf_test_kbuild_prog, .desc = "Test kbuild searching", }, + [LLVM_TESTCASE_BPF_PROLOGUE] = { + .source = test_llvm__bpf_test_prologue_prog, + .desc = "Test BPF prologue generation", + }, }; diff --git a/tools/perf/tests/llvm.h b/tools/perf/tests/llvm.h index d91d8f44efee..5150b4d6ef50 100644 --- a/tools/perf/tests/llvm.h +++ b/tools/perf/tests/llvm.h @@ -6,10 +6,12 @@ extern const char test_llvm__bpf_base_prog[]; extern const char test_llvm__bpf_test_kbuild_prog[]; +extern const char test_llvm__bpf_test_prologue_prog[]; enum test_llvm__testcase { LLVM_TESTCASE_BASE, LLVM_TESTCASE_KBUILD, + LLVM_TESTCASE_BPF_PROLOGUE, __LLVM_TESTCASE_MAX, }; -- 2.30.2