Hello, This is the 11th version of the series to fix the stacktrace with kretprobe on x86. The previous version is here; https://lore.kernel.org/all/162756755600.301564.4957591913842010341.stgit@devnote2/ This version is rebased on the latest tip/master branch and includes the kprobe cleanup series[1][2]. No code change. [1] https://lore.kernel.org/bpf/162748615977.59465.13262421617578791515.stgit@devnote2/ [2] https://lore.kernel.org/linux-csky/20210727133426.2919710-1-punitagrawal@xxxxxxxxx/ With this series, unwinder can unwind stack correctly from ftrace as below; # cd /sys/kernel/debug/tracing # echo > trace # echo 1 > options/sym-offset # echo r vfs_read >> kprobe_events # echo r full_proxy_read >> kprobe_events # echo traceoff:1 > events/kprobes/r_vfs_read_0/trigger # echo stacktrace:1 > events/kprobes/r_full_proxy_read_0/trigger # echo 1 > events/kprobes/enable # cat /sys/kernel/debug/kprobes/list ffffffff813bedf0 r full_proxy_read+0x0 [FTRACE] ffffffff812c13e0 r vfs_read+0x0 [FTRACE] # echo 0 > events/kprobes/enable # cat trace # tracer: nop # # entries-in-buffer/entries-written: 3/3 #P:8 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / _-=> migrate-disable # |||| / delay # TASK-PID CPU# ||||| TIMESTAMP FUNCTION # | | | ||||| | | cat-136 [000] ...1. 14.474966: r_full_proxy_read_0: (vfs_read+0x99/0x190 <- full_proxy_read) cat-136 [000] ...1. 14.474970: <stack trace> => kretprobe_trace_func+0x209/0x300 => kretprobe_dispatcher+0x9d/0xb0 => __kretprobe_trampoline_handler+0xd4/0x1b0 => trampoline_handler+0x43/0x60 => __kretprobe_trampoline+0x2a/0x50 => vfs_read+0x99/0x190 => ksys_read+0x68/0xe0 => do_syscall_64+0x3b/0x90 => entry_SYSCALL_64_after_hwframe+0x44/0xae cat-136 [000] ...1. 14.474971: r_vfs_read_0: (ksys_read+0x68/0xe0 <- vfs_read) This shows the double return probes (vfs_read() and full_proxy_read()) on the stack correctly unwinded. (vfs_read() returns to 'ksys_read+0x68' and full_proxy_read() returns to 'vfs_read+0x99') This also changes the kretprobe behavisor a bit, now the instraction pointer in the 'pt_regs' passed to kretprobe user handler is correctly set the real return address. So user handlers can get it via instruction_pointer() API, and can use stack_trace_save_regs(). You can also get this series from git://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git kprobes/kretprobe-stackfix-v11 Thank you, --- Josh Poimboeuf (3): objtool: Add frame-pointer-specific function ignore objtool: Ignore unwind hints for ignored functions x86/kprobes: Add UNWIND_HINT_FUNC on kretprobe_trampoline() Masami Hiramatsu (19): kprobes: treewide: Cleanup the error messages for kprobes kprobes: Fix coding style issues kprobes: Use IS_ENABLED() instead of kprobes_built_in() kprobes: Add assertions for required lock kprobes: treewide: Use 'kprobe_opcode_t *' for the code address in get_optimized_kprobe() kprobes: Use bool type for functions which returns boolean value ia64: kprobes: Fix to pass correct trampoline address to the handler kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbol_descriptor() kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler() kprobes: treewide: Make it harder to refer kretprobe_trampoline directly kprobes: Add kretprobe_find_ret_addr() for searching return address ARC: Add instruction_pointer_set() API ia64: Add instruction_pointer_set() API arm: kprobes: Make space for instruction pointer on stack kprobes: Enable stacktrace from pt_regs in kretprobe handler x86/kprobes: Push a fake return address at kretprobe_trampoline x86/unwind: Recover kretprobe trampoline entry tracing: Show kretprobe unknown indicator only for kretprobe_trampoline x86/kprobes: Fixup return address in generic trampoline handler Punit Agrawal (5): kprobes: Do not use local variable when creating debugfs file kprobes: Use helper to parse boolean input from userspace kprobe: Simplify prepare_kprobe() by dropping redundant version csky: ftrace: Drop duplicate implementation of arch_check_ftrace_location() kprobes: Make arch_check_ftrace_location static arch/arc/include/asm/kprobes.h | 2 arch/arc/include/asm/ptrace.h | 5 arch/arc/kernel/kprobes.c | 13 - arch/arm/probes/kprobes/core.c | 15 - arch/arm/probes/kprobes/opt-arm.c | 7 arch/arm64/include/asm/kprobes.h | 2 arch/arm64/kernel/probes/kprobes.c | 10 arch/arm64/kernel/probes/kprobes_trampoline.S | 4 arch/csky/include/asm/kprobes.h | 2 arch/csky/kernel/probes/ftrace.c | 7 arch/csky/kernel/probes/kprobes.c | 14 - arch/csky/kernel/probes/kprobes_trampoline.S | 4 arch/ia64/include/asm/ptrace.h | 5 arch/ia64/kernel/kprobes.c | 15 - arch/mips/kernel/kprobes.c | 26 + arch/parisc/kernel/kprobes.c | 6 arch/powerpc/include/asm/kprobes.h | 2 arch/powerpc/kernel/kprobes.c | 29 - arch/powerpc/kernel/optprobes.c | 8 arch/powerpc/kernel/stacktrace.c | 2 arch/riscv/include/asm/kprobes.h | 2 arch/riscv/kernel/probes/kprobes.c | 15 - arch/riscv/kernel/probes/kprobes_trampoline.S | 4 arch/s390/include/asm/kprobes.h | 2 arch/s390/kernel/kprobes.c | 16 - arch/s390/kernel/stacktrace.c | 2 arch/sh/include/asm/kprobes.h | 2 arch/sh/kernel/kprobes.c | 12 - arch/sparc/include/asm/kprobes.h | 2 arch/sparc/kernel/kprobes.c | 12 - arch/x86/include/asm/kprobes.h | 1 arch/x86/include/asm/unwind.h | 23 + arch/x86/include/asm/unwind_hints.h | 5 arch/x86/kernel/kprobes/core.c | 71 +++- arch/x86/kernel/kprobes/opt.c | 6 arch/x86/kernel/unwind_frame.c | 3 arch/x86/kernel/unwind_guess.c | 3 arch/x86/kernel/unwind_orc.c | 21 + include/linux/kprobes.h | 113 ++++-- include/linux/objtool.h | 12 + kernel/kprobes.c | 502 ++++++++++++++----------- kernel/trace/trace_kprobe.c | 2 kernel/trace/trace_output.c | 17 - lib/error-inject.c | 3 tools/include/linux/objtool.h | 12 + tools/objtool/check.c | 2 46 files changed, 607 insertions(+), 436 deletions(-) -- Masami Hiramatsu (Linaro) <mhiramat@xxxxxxxxxx>
