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powerpc/ptrace: Combine SYSCALL_EMU & SYSCALL_TRACE handling 

Combine the SYSCALL_EMU and SYSCALL_TRACE handling so that we only
call tracehook_report_syscall_entry() in one place.

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
[mpe: Flesh out change log, s/cached_flags/flags/, reflow comments]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Dmitry V. Levin 2018-12-16 20:28:28 +03:00 committed by Michael Ellerman
parent 25078dc1f7
commit 8dbdec0bcb
1 changed files with 31 additions and 23 deletions
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54
arch/powerpc/kernel/ptrace.c
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@ -3263,32 +3263,40 @@ static inline int do_seccomp(struct pt_regs *regs) { return 0; }
*/
long do_syscall_trace_enter(struct pt_regs *regs)
{
u32 flags;
user_exit();
if (test_thread_flag(TIF_SYSCALL_EMU)) {
/*
* A nonzero return code from tracehook_report_syscall_entry()
* tells us to prevent the syscall execution, but we are not
* going to execute it anyway.
*
* Returning -1 will skip the syscall execution. We want to
* avoid clobbering any register also, thus, not 'gotoing'
* skip label.
*/
if (tracehook_report_syscall_entry(regs))
;
return -1;
}
flags = READ_ONCE(current_thread_info()->flags) &
(_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE);
/*
* The tracer may decide to abort the syscall, if so tracehook
* will return !0. Note that the tracer may also just change
* regs->gpr[0] to an invalid syscall number, that is handled
* below on the exit path.
*/
if (test_thread_flag(TIF_SYSCALL_TRACE) &&
tracehook_report_syscall_entry(regs))
goto skip;
if (flags) {
int rc = tracehook_report_syscall_entry(regs);
if (unlikely(flags & _TIF_SYSCALL_EMU)) {
/*
* A nonzero return code from
* tracehook_report_syscall_entry() tells us to prevent
* the syscall execution, but we are not going to
* execute it anyway.
*
* Returning -1 will skip the syscall execution. We want
* to avoid clobbering any registers, so we don't goto
* the skip label below.
*/
return -1;
}
if (rc) {
/*
* The tracer decided to abort the syscall. Note that
* the tracer may also just change regs->gpr[0] to an
* invalid syscall number, that is handled below on the
* exit path.
*/
goto skip;
}
}
/* Run seccomp after ptrace; allow it to set gpr[3]. */
if (do_seccomp(regs))