Oops, please ignore this. I missed updating the version. Thanks, On Mon, 22 Mar 2021 15:36:46 +0900 Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote: > Hello, > > Here is the 4th version of the series to fix the stacktrace with kretprobe > on x86. After merging this, I'll fix other architectures. > > The previous version is; > > https://lore.kernel.org/bpf/161615650355.306069.17260992641363840330.stgit@devnote2/ > > This version fixes some build warnings/errors and a bug on arm. (I think > arm's kretprobe implementation is a bit odd. anyway, that is off topic.) > [5/12] fixes objtool warning when CONFIG_FRAME_POINTER=y. [7/12] fixes a > build error on ia64. And add [8/12] for avoiding stack corruption by > instruction_pointer_set() in kretprobe_trampoline_handler on arm. > > With this series, unwinder can unwind stack correctly from ftrace as below; > > # cd /sys/kernel/debug/tracing > # echo > trace > # 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 > # echo 1 > options/sym-offset > # cat /sys/kernel/debug/kprobes/list > ffffffff8133b740 r full_proxy_read+0x0 [FTRACE] > ffffffff812560b0 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 > # ||| / delay > # TASK-PID CPU# |||| TIMESTAMP FUNCTION > # | | | |||| | | > <...>-135 [005] ...1 9.422114: r_full_proxy_read_0: (vfs_read+0xab/0x1a0 <- full_proxy_read) > <...>-135 [005] ...1 9.422158: <stack trace> > => kretprobe_trace_func+0x209/0x2f0 > => kretprobe_dispatcher+0x4a/0x70 > => __kretprobe_trampoline_handler+0xca/0x150 > => trampoline_handler+0x44/0x70 > => kretprobe_trampoline+0x2a/0x50 > => vfs_read+0xab/0x1a0 > => ksys_read+0x5f/0xe0 > => do_syscall_64+0x33/0x40 > => entry_SYSCALL_64_after_hwframe+0x44/0xae > => 0 > > This shows the double return probes (vfs_read and full_proxy_read) on the stack > correctly unwinded. (vfs_read was called from ksys_read+0x5f and full_proxy_read > was called from vfs_read+0xab) > > This actually 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. > > You can also get this series from > git://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git kprobes/kretprobe-stackfix-v4 > > > Thank you, > > --- > > Josh Poimboeuf (1): > x86/kprobes: Add UNWIND_HINT_FUNC on kretprobe_trampoline code > > Masami Hiramatsu (11): > ia64: kprobes: Fix to pass correct trampoline address to the handler > kprobes: treewide: Replace arch_deref_entry_point() with dereference_function_descriptor() > kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler() > 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 a space for regs->ARM_pc at kretprobe_trampoline > kprobes: Setup instruction pointer in __kretprobe_trampoline_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 > > > arch/arc/include/asm/ptrace.h | 5 ++ > arch/arc/kernel/kprobes.c | 2 - > arch/arm/probes/kprobes/core.c | 5 +- > arch/arm64/kernel/probes/kprobes.c | 3 - > arch/csky/kernel/probes/kprobes.c | 2 - > arch/ia64/include/asm/ptrace.h | 5 ++ > arch/ia64/kernel/kprobes.c | 15 ++--- > arch/mips/kernel/kprobes.c | 3 - > arch/parisc/kernel/kprobes.c | 4 + > arch/powerpc/kernel/kprobes.c | 13 ----- > arch/riscv/kernel/probes/kprobes.c | 2 - > arch/s390/kernel/kprobes.c | 2 - > arch/sh/kernel/kprobes.c | 2 - > arch/sparc/kernel/kprobes.c | 2 - > arch/x86/include/asm/kprobes.h | 1 > arch/x86/include/asm/unwind.h | 17 ++++++ > arch/x86/include/asm/unwind_hints.h | 5 ++ > arch/x86/kernel/kprobes/core.c | 44 ++++++++++++---- > arch/x86/kernel/unwind_frame.c | 4 + > arch/x86/kernel/unwind_guess.c | 3 - > arch/x86/kernel/unwind_orc.c | 6 +- > include/linux/kprobes.h | 41 ++++++++++++-- > kernel/kprobes.c | 99 ++++++++++++++++++++++++----------- > kernel/trace/trace_output.c | 17 +----- > lib/error-inject.c | 3 + > 25 files changed, 200 insertions(+), 105 deletions(-) > > -- > Masami Hiramatsu (Linaro) <mhiramat@xxxxxxxxxx> -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
