linux/tools/objtool
Peter Zijlstra 38e0e4d04d x86/ibt, objtool: Don't discard text references from tracepoint section
On Tue, Jun 28, 2022 at 04:28:58PM +0800, Pengfei Xu wrote:

> # ./ftracetest
> === Ftrace unit tests ===
> [1] Basic trace file check      [PASS]
> [2] Basic test for tracers      [PASS]
> [3] Basic trace clock test      [PASS]
> [4] Basic event tracing check   [PASS]
> [5] Change the ringbuffer size  [PASS]
> [6] Snapshot and tracing setting        [PASS]
> [7] trace_pipe and trace_marker [PASS]
> [8] Test ftrace direct functions against tracers        [UNRESOLVED]
> [9] Test ftrace direct functions against kprobes        [UNRESOLVED]
> [10] Generic dynamic event - add/remove eprobe events   [FAIL]
> [11] Generic dynamic event - add/remove kprobe events
>
> It 100% reproduced in step 11 and then missing ENDBR BUG generated:
> "
> [ 9332.752836] mmiotrace: enabled CPU7.
> [ 9332.788612] mmiotrace: disabled.
> [ 9337.103426] traps: Missing ENDBR: syscall_regfunc+0x0/0xb0

It turns out that while syscall_regfunc() does have an ENDBR when
generated, it gets sealed by objtool's .ibt_endbr_seal list.

Since the only text references to this function:

  $ git grep syscall_regfunc
  include/linux/tracepoint.h:extern int syscall_regfunc(void);
  include/trace/events/syscalls.h:        syscall_regfunc, syscall_unregfunc
  include/trace/events/syscalls.h:        syscall_regfunc, syscall_unregfunc
  kernel/tracepoint.c:int syscall_regfunc(void)

appear in the __tracepoint section which is excluded by objtool.

Fixes: 3c6f9f77e6 ("objtool: Rework ibt and extricate from stack validation")
Reported-by: Pengfei Xu <pengfei.xu@intel.com
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/Yrrepdaow4F5kqG0@hirez.programming.kicks-ass.net
2022-07-07 13:26:54 +02:00
..
arch/x86 objtool: Reorganize cmdline options 2022-04-22 12:32:01 +02:00
Documentation objtool: Update documentation 2022-04-22 12:32:05 +02:00
include/objtool objtool: Fix objtool regression on x32 systems 2022-05-20 12:45:30 +02:00
.gitignore objtool: Rework header include paths 2021-01-13 18:13:14 -06:00
Build objtool: Ditch subcommands 2022-04-22 12:32:01 +02:00
builtin-check.c objtool: Remove --lto and --vmlinux in favor of --link 2022-04-22 12:32:05 +02:00
check.c x86/ibt, objtool: Don't discard text references from tracepoint section 2022-07-07 13:26:54 +02:00
elf.c objtool: Fix objtool regression on x32 systems 2022-05-20 12:45:30 +02:00
Makefile Kbuild updates for v5.19 2022-05-26 12:09:50 -07:00
objtool.c objtool: Ditch subcommands 2022-04-22 12:32:01 +02:00
orc_dump.c x86/unwind/orc: Change REG_SP_INDIRECT 2021-02-10 20:53:51 +01:00
orc_gen.c Merge branch 'objtool/urgent' 2021-10-07 00:40:17 +02:00
special.c objtool,x86: Replace alternatives with .retpoline_sites 2021-10-28 23:25:25 +02:00
sync-check.sh Merge branch 'x86/cpu' into WIP.x86/core, to merge the NOP changes & resolve a semantic conflict 2021-04-02 12:36:30 +02:00
weak.c objtool: Ditch subcommands 2022-04-22 12:32:01 +02:00