Message ID | 20181216172828.GA25359@altlinux.org (mailing list archive) |
---|---|
State | Accepted |
Commit | 8dbdec0bcb416d0ef0bfd737620d08f5160ac290 |
Headers | show |
Series | powerpc/ptrace: cleanup do_syscall_trace_enter | expand |
Context | Check | Description |
---|---|---|
snowpatch_ozlabs/apply_patch | warning | next/apply_patch Patch failed to apply |
snowpatch_ozlabs/apply_patch | fail | Failed to apply to any branch |
"Dmitry V. Levin" <ldv@altlinux.org> writes: > Invoke tracehook_report_syscall_entry once. Thanks. > Signed-off-by: Dmitry V. Levin <ldv@altlinux.org> > --- > arch/powerpc/kernel/ptrace.c | 54 +++++++++++++++++++++--------------- > 1 file changed, 31 insertions(+), 23 deletions(-) > > diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c > index 714c3480c52d..8794d32c2d9e 100644 > --- a/arch/powerpc/kernel/ptrace.c > +++ b/arch/powerpc/kernel/ptrace.c > @@ -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 cached_flags; > + Do you mind if I just call it "flags", I find "cached_flags" a bit unwieldy for some reason. I'm happy to fix it up when applying. cheers > 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; > - } > + cached_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 (cached_flags) { > + int rc = tracehook_report_syscall_entry(regs); > + > + if (unlikely(cached_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 register also, > + * thus, not 'gotoing' skip label. > + */ > + 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)) > -- > ldv
Hi, On Mon, Dec 17, 2018 at 10:20:26PM +1100, Michael Ellerman wrote: > "Dmitry V. Levin" <ldv@altlinux.org> writes: > > Invoke tracehook_report_syscall_entry once. > > Thanks. > > > Signed-off-by: Dmitry V. Levin <ldv@altlinux.org> > > --- > > arch/powerpc/kernel/ptrace.c | 54 +++++++++++++++++++++--------------- > > 1 file changed, 31 insertions(+), 23 deletions(-) > > > > diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c > > index 714c3480c52d..8794d32c2d9e 100644 > > --- a/arch/powerpc/kernel/ptrace.c > > +++ b/arch/powerpc/kernel/ptrace.c > > @@ -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 cached_flags; > > + > > Do you mind if I just call it "flags", I find "cached_flags" a bit > unwieldy for some reason. > > I'm happy to fix it up when applying. No problem, feel free to call it whatever you like. Thanks,
On 12/16, Dmitry V. Levin wrote: > > long do_syscall_trace_enter(struct pt_regs *regs) > { > + u32 cached_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; > - } > + cached_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 (cached_flags) { > + int rc = tracehook_report_syscall_entry(regs); > + > + if (unlikely(cached_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 register also, > + * thus, not 'gotoing' skip label. > + */ > + 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; > + } > + } Looks good to me, Oleg.
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c index 714c3480c52d..8794d32c2d9e 100644 --- a/arch/powerpc/kernel/ptrace.c +++ b/arch/powerpc/kernel/ptrace.c @@ -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 cached_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; - } + cached_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 (cached_flags) { + int rc = tracehook_report_syscall_entry(regs); + + if (unlikely(cached_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 register also, + * thus, not 'gotoing' skip label. + */ + 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))
Invoke tracehook_report_syscall_entry once. Signed-off-by: Dmitry V. Levin <ldv@altlinux.org> --- arch/powerpc/kernel/ptrace.c | 54 +++++++++++++++++++++--------------- 1 file changed, 31 insertions(+), 23 deletions(-)