diff options
| author | Gabriel Krisman Bertazi | 2021-02-03 13:00:48 -0500 |
|---|---|---|
| committer | Thomas Gleixner | 2021-02-06 00:21:42 +0100 |
| commit | 6342adcaa683c2b705c24ed201dc11b35854c88d (patch) | |
| tree | d75d12186c1d9e79168bdd0b84740d7701bee408 /include/linux/entry-common.h | |
| parent | 1048ba83fb1c00cd24172e23e8263972f6b5d9ac (diff) | |
entry: Ensure trap after single-step on system call return
Commit 299155244770 ("entry: Drop usage of TIF flags in the generic syscall
code") introduced a bug on architectures using the generic syscall entry
code, in which processes stopped by PTRACE_SYSCALL do not trap on syscall
return after receiving a TIF_SINGLESTEP.
The reason is that the meaning of TIF_SINGLESTEP flag is overloaded to
cause the trap after a system call is executed, but since the above commit,
the syscall call handler only checks for the SYSCALL_WORK flags on the exit
work.
Split the meaning of TIF_SINGLESTEP such that it only means single-step
mode, and create a new type of SYSCALL_WORK to request a trap immediately
after a syscall in single-step mode. In the current implementation, the
SYSCALL_WORK flag shadows the TIF_SINGLESTEP flag for simplicity.
Update x86 to flip this bit when a tracer enables single stepping.
Fixes: 299155244770 ("entry: Drop usage of TIF flags in the generic syscall code")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kyle Huey <me@kylehuey.com>
Link: https://lore.kernel.org/r/87h7mtc9pr.fsf_-_@collabora.com
Diffstat (limited to 'include/linux/entry-common.h')
| -rw-r--r-- | include/linux/entry-common.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index ca86a00abe86..a104b298019a 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -46,6 +46,7 @@ SYSCALL_WORK_SYSCALL_TRACE | \ SYSCALL_WORK_SYSCALL_AUDIT | \ SYSCALL_WORK_SYSCALL_USER_DISPATCH | \ + SYSCALL_WORK_SYSCALL_EXIT_TRAP | \ ARCH_SYSCALL_WORK_EXIT) /* |