Hello, This patchset implements memory (address), stack[N], deference, bitfield, retval (it needs uretprobe tho) and file_offset fetch methods for uprobes. It's based on the previous work [1] done by Hyeoncheol Lee.
Now kprobes and uprobes have their own fetch_type_tables and, in turn, memory and stack access methods. The symbol and file_offset fetch methods are only available to kprobes and uprobes, respectively. Other fetch methods are shared. For the file_offset method, it translates the offset argument to a virtual address in a process. To do that, it calculates base mapping address using probe address (utask->vaddr) and probe offset (tu->offset) and then adds the argument offset. Those info are carried via utask and a new fetch parameter. The syntax is '@+offset' where offset are relative address to the base address. For shared libraries, it'd be simply the st_value of symbol in ELF format. But for executable, it needs to subtract base load address (e.g. 0x40000 for x86_64) from the symbol value. Please see previous discussion for an example [2] - Note that the syntax changed to '@+' from plain '@'. The plain '@addr' syntax is used for accessing absolute memory address if you already know the exact address. Many thanks to Oleg who provides valuable feedbacks and suggestions. The patch 1-2 are bug fixes and can be applied independently. The patch 16 is a preparation for patch 17 which implements the file_offset fetch method. * v9 changes: - [ku]probes_fetch_type_table have NULL terminator (Masami) - make symbol fetch methods static inline for !CONFIG_KPROBE_EVENT (Masami) - add more Ack's from Masami * v8 changes: - rename tk, tu and tp more consistently (Srikar) - change prefix format specifier: %#x -> 0x%x (Masami) - convert file_offset_param to uprobe_dispatch_data (Oleg) - add more Ack's from Srikar and Masami * v7 changes: - restructure patches not to break build with !CONFIG_[KU]PROBE_EVENT - print 0x prefix for unsigned types - add @+file_offset fetch method (Oleg) - get rid of uprobe_buffer_mutex (Oleg) - pass 'is_return' to uprobes argument parser [1] https://lkml.org/lkml/2012/11/14/84 [2] https://lkml.org/lkml/2013/11/5/25 A simple example: # cat foo.c int glob = -1; char str[] = "hello uprobe."; struct foo { unsigned int unused: 2; unsigned int foo: 20; unsigned int bar: 10; } foo = { .foo = 5, }; int main(int argc, char *argv[]) { long local = 0x1234; return 127; } # gcc -o foo -g foo.c # objdump -d foo | grep -A9 -F '<main>' 00000000004004b0 <main>: 4004b0: 55 push %rbp 4004b1: 48 89 e5 mov %rsp,%rbp 4004b4: 89 7d ec mov %edi,-0x14(%rbp) 4004b7: 48 89 75 e0 mov %rsi,-0x20(%rbp) 4004bb: 48 c7 45 f8 34 12 00 movq $0x1234,-0x8(%rbp) 4004c2: 00 4004c3: b8 7f 00 00 00 mov $0x7f,%eax 4004c8: 5d pop %rbp 4004c9: c3 retq # nm foo | grep -e glob$ -e str -e foo 00000000006008bc D foo 00000000006008a8 D glob 00000000006008ac D str # perf probe -x /home/namhyung/tmp/foo -a 'foo=main+0x13 glob=@0x6008a8:s32 \ > str=@+0x2008ac:string bit=@+0x2008bc:b10@2/32 argc=%di:s32 local=-0x8(%bp)' Added new event: probe_foo:foo (on 0x4c3 with glob=@0x6008a8:s32 str=@+0x2008ac:string bit=@+0x2008bc:b10@2/32 argc=%di:s32 local=-0x8(%bp)) You can now use it in all perf tools, such as: perf record -e probe_foo:foo -aR sleep 1 # perf record -e probe_foo:foo ./foo [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.001 MB perf.data (~33 samples) ] # perf script | grep -v ^# foo 2008 [002 2199.867154: probe_foo:foo (4004c3) glob=-1 str="hello uprobe." bit=0x5 argc=1 local=0x1234 This patchset is based on the current for-next branch of the Steven Rostedt's linux-trace tree. I also put this on my 'uprobe/fetch-v9' branch in my tree: git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git Any comments are welcome, thanks. Namhyung Cc: Masami Hiramatsu <masami.hiramatsu...@hitachi.com> Cc: Srikar Dronamraju <sri...@linux.vnet.ibm.com> Cc: Oleg Nesterov <o...@redhat.com> Cc: zhangwei(Jovi) <jovi.zhang...@huawei.com> Cc: Arnaldo Carvalho de Melo <a...@ghostprotocols.net> Cc: Hemant Kumar <hks...@linux.vnet.ibm.com> Hyeoncheol Lee (1): tracing/probes: Add fetch{,_size} member into deref fetch method Namhyung Kim (15): tracing/uprobes: Fix documentation of uprobe registration syntax tracing/probes: Fix basic print type functions tracing/kprobes: Factor out struct trace_probe tracing/uprobes: Convert to struct trace_probe tracing/kprobes: Move common functions to trace_probe.h tracing/probes: Integrate duplicate set_print_fmt() tracing/probes: Move fetch function helpers to trace_probe.h tracing/probes: Split [ku]probes_fetch_type_table tracing/probes: Implement 'stack' fetch method for uprobes tracing/probes: Move 'symbol' fetch method to kprobes tracing/probes: Implement 'memory' fetch method for uprobes tracing/uprobes: Pass 'is_return' to traceprobe_parse_probe_arg() tracing/uprobes: Fetch args before reserving a ring buffer tracing/uprobes: Add support for full argument access methods tracing/uprobes: Add @+file_offset fetch method Oleg Nesterov (1): uprobes: Allocate ->utask before handler_chain() for tracing handlers Documentation/trace/uprobetracer.txt | 36 +- kernel/events/uprobes.c | 4 + kernel/trace/trace_kprobe.c | 812 +++++++++++++++++++---------------- kernel/trace/trace_probe.c | 440 +++++++------------ kernel/trace/trace_probe.h | 216 ++++++++++ kernel/trace/trace_uprobe.c | 495 +++++++++++++++------ 6 files changed, 1208 insertions(+), 795 deletions(-) -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
