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Message-Id: <162756755600.301564.4957591913842010341.stgit@devnote2>
Date: Thu, 29 Jul 2021 23:05:56 +0900
From: Masami Hiramatsu <mhiramat@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Ingo Molnar <mingo@...nel.org>
Cc: X86 ML <x86@...nel.org>, Masami Hiramatsu <mhiramat@...nel.org>,
Daniel Xu <dxu@...uu.xyz>, linux-kernel@...r.kernel.org,
bpf@...r.kernel.org, kuba@...nel.org, mingo@...hat.com,
ast@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>,
Peter Zijlstra <peterz@...radead.org>, kernel-team@...com,
yhs@...com, linux-ia64@...r.kernel.org,
Abhishek Sagar <sagar.abhishek@...il.com>,
Andrii Nakryiko <andrii.nakryiko@...il.com>
Subject: [PATCH -tip v10 00/16] kprobes: Fix stacktrace with kretprobes on x86
Hello,
This is the 10th version of the series to fix the stacktrace with kretprobe on x86.
The previous version is here;
https://lore.kernel.org/bpf/162601048053.1318837.1550594515476777588.stgit@devnote2/
This version is rebased on top of new kprobes cleanup series(*1) and merging
Josh's objtool update series (*2)(*3) as [6/16] and [7/16].
(*1) https://lore.kernel.org/bpf/162748615977.59465.13262421617578791515.stgit@devnote2/
(*2) https://lore.kernel.org/bpf/20210710192433.x5cgjsq2ksvaqnss@treble/
(*3) https://lore.kernel.org/bpf/20210710192514.ghvksi3ozhez4lvb@treble/
Changes from v9:
- Add Josh's objtool update patches with a build error fix as [6/16] and [7/16].
- Add a API document for kretprobe_find_ret_addr() and check cur != NULL in [5/16].
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
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
# | | | |||| | |
<...>-134 [007] ...1 16.185877: r_full_proxy_read_0: (vfs_read+0x98/0x180 <- full_proxy_read)
<...>-134 [007] ...1 16.185901: <stack trace>
=> kretprobe_trace_func+0x209/0x300
=> kretprobe_dispatcher+0x4a/0x70
=> __kretprobe_trampoline_handler+0xd4/0x170
=> trampoline_handler+0x43/0x60
=> kretprobe_trampoline+0x2a/0x50
=> vfs_read+0x98/0x180
=> ksys_read+0x5f/0xe0
=> do_syscall_64+0x37/0x90
=> entry_SYSCALL_64_after_hwframe+0x44/0xae
<...>-134 [007] ...1 16.185902: r_vfs_read_0: (ksys_read+0x5f/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+0x5f' and full_proxy_read()
returns to 'vfs_read+0x98')
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-v9
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 (13):
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
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 | 11 +-
arch/arm64/include/asm/kprobes.h | 2
arch/arm64/kernel/probes/kprobes.c | 5 -
arch/arm64/kernel/probes/kprobes_trampoline.S | 4 -
arch/csky/include/asm/kprobes.h | 2
arch/csky/kernel/probes/kprobes.c | 4 -
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 | 15 +--
arch/parisc/kernel/kprobes.c | 6 +
arch/powerpc/include/asm/kprobes.h | 2
arch/powerpc/kernel/kprobes.c | 29 ++---
arch/powerpc/kernel/optprobes.c | 2
arch/powerpc/kernel/stacktrace.c | 2
arch/riscv/include/asm/kprobes.h | 2
arch/riscv/kernel/probes/kprobes.c | 4 -
arch/riscv/kernel/probes/kprobes_trampoline.S | 4 -
arch/s390/include/asm/kprobes.h | 2
arch/s390/kernel/kprobes.c | 12 +-
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/unwind_frame.c | 3 -
arch/x86/kernel/unwind_guess.c | 3 -
arch/x86/kernel/unwind_orc.c | 21 +++-
include/linux/kprobes.h | 44 +++++++-
include/linux/objtool.h | 12 ++
kernel/kprobes.c | 133 +++++++++++++++++++------
kernel/trace/trace_output.c | 17 +--
lib/error-inject.c | 3 -
tools/include/linux/objtool.h | 12 ++
tools/objtool/check.c | 2
42 files changed, 360 insertions(+), 172 deletions(-)
--
Masami Hiramatsu (Linaro) <mhiramat@...nel.org>
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