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linux-next/tools/perf/tests/bpf-script-test-prologue.c

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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 <SNIP> 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 <uapi/linux/fs.h> #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 <wangnan0@huawei.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Zefan Li <lizefan@huawei.com> 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 <acme@redhat.com>
2015-11-16 20:10:14 +08:00
/*
* 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 <uapi/linux/fs.h>
perf test llvm: Avoid error when PROFILE_ALL_BRANCHES is set The 'if' keyword is a define that expands to complex code when CONFIG_PROFILE_ALL_BRANCHES is selected, which causes a 'perf test LLVM' failure like: $ ./perf test LLVM 35: LLVM search and compile : 35.1: Basic BPF llvm compile : Ok 35.2: kbuild searching : Ok 35.3: Compile source for BPF prologue generation: FAILED! 35.4: Compile source for BPF relocation : Skip The only affected test case is bpf-script-test-prologue.c because it uses kernel headers and has 'if' inside. This patch undefines 'if' to make it passes perf test. More detailed analysis from a message in this thread, also by Wang: The problem is caused by following relocation information: $ readelf -a ./llvmsubtest3 ... [ 5] _ftrace_branch PROGBITS 0000000000000000 00000260 00000000000000a0 0000000000000000 WA 0 0 4 ... Relocation section '.relfunc=null_lseek file->f_mode offset orig' at offset 0x490 contains 4 entries: Offset Info Type Sym. Value Sym. Name 000000000038 000b00000001 unrecognized: 1 0000000000000000 _ftrace_branch 0000000000b0 000b00000001 unrecognized: 1 0000000000000000 _ftrace_branch 000000000128 000b00000001 unrecognized: 1 0000000000000000 _ftrace_branch 0000000001c0 000b00000001 unrecognized: 1 0000000000000000 _ftrace_branch Relocation section '.rel_ftrace_branch' at offset 0x4d0 contains 8 entries: Offset Info Type Sym. Value Sym. Name 000000000000 000200000001 unrecognized: 1 0000000000000000 .L__func__.bpf_func__n 000000000008 000100000001 unrecognized: 1 0000000000000015 .L.str 000000000028 000200000001 unrecognized: 1 0000000000000000 .L__func__.bpf_func__n 000000000030 000100000001 unrecognized: 1 0000000000000015 .L.str 000000000050 000200000001 unrecognized: 1 0000000000000000 .L__func__.bpf_func__n 000000000058 000100000001 unrecognized: 1 0000000000000015 .L.str 000000000078 000200000001 unrecognized: 1 0000000000000000 .L__func__.bpf_func__n 000000000080 000100000001 unrecognized: 1 0000000000000015 .L.str ... So I think the failure is because you enabled CONFIG_PROFILE_ALL_BRANCHES. I can reproduce your buggy result by selecting CONFIG_PROFILE_ALL_BRANCHES in my kbuild: $ ./perf test LLVM 35: LLVM search and compile : 35.1: Basic BPF llvm compile : Ok 35.2: kbuild searching : Ok 35.3: Compile source for BPF prologue generation: FAILED! 35.4: Compile source for BPF relocation : Skip Simply undef CONFIG_PROFILE_ALL_BRANCHES in clang opts not working because it is introduced by "#include <uapi/linux/fs.h>", which override cmdline options. So I think the best way is to undefine 'if' inside BPF script. Reported-and-Tested-by: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com> Signed-off-by: Wang Nan <wangnan0@huawei.com> Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com> Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Cc: Zefan Li <lizefan@huawei.com> Link: http://lkml.kernel.org/r/20170620183203.2517-1-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2017-06-21 02:32:03 +08:00
/*
* If CONFIG_PROFILE_ALL_BRANCHES is selected,
* 'if' is redefined after include kernel header.
* Recover 'if' for BPF object code.
*/
#ifdef if
# undef if
#endif
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 <SNIP> 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 <uapi/linux/fs.h> #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 <wangnan0@huawei.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Zefan Li <lizefan@huawei.com> 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 <acme@redhat.com>
2015-11-16 20:10:14 +08:00
#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;
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