From: "Dmitry V. Levin" <ldv@altlinux.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Oleg Nesterov <oleg@redhat.com>,
Eugene Syromyatnikov <esyr@redhat.com>,
Elvira Khabirova <lineprinter@altlinux.org>,
Paul Mackerras <paulus@samba.org>,
Andy Lutomirski <luto@kernel.org>,
Breno Leitao <leitao@debian.org>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4] powerpc/ptrace: replace ptrace_report_syscall() with a tracehook call
Date: Mon, 3 Dec 2018 06:18:23 +0300 [thread overview]
Message-ID: <20181203031823.GE11573@altlinux.org> (raw)
In-Reply-To: <87efbe166y.fsf@concordia.ellerman.id.au>
From: Elvira Khabirova <lineprinter@altlinux.org>
Arch code should use tracehook_*() helpers, as documented
in include/linux/tracehook.h,
ptrace_report_syscall() is not expected to be used outside that file.
Co-authored-by: Dmitry V. Levin <ldv@altlinux.org>
Fixes: 5521eb4bca2d ("powerpc/ptrace: Add support for PTRACE_SYSEMU")
Signed-off-by: Elvira Khabirova <lineprinter@altlinux.org>
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
---
v4: rewritten to call tracehook_report_syscall_entry() once, compile-tested
v3: add a descriptive comment
v2: explicitly ignore tracehook_report_syscall_entry() return code
arch/powerpc/kernel/ptrace.c | 54 +++++++++++++++++++++++-------------
1 file changed, 35 insertions(+), 19 deletions(-)
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index afb819f4ca68..59c8c9a3d7ea 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -3263,27 +3263,43 @@ static inline int do_seccomp(struct pt_regs *regs) { return 0; }
*/
long do_syscall_trace_enter(struct pt_regs *regs)
{
+ struct thread_info *ti;
+ u32 cached_flags;
+
user_exit();
- if (test_thread_flag(TIF_SYSCALL_EMU)) {
- ptrace_report_syscall(regs);
- /*
- * Returning -1 will skip the syscall execution. We want to
- * avoid clobbering any register also, thus, not 'gotoing'
- * skip label.
- */
- return -1;
- }
+ ti = current_thread_info();
+ cached_flags =
+ READ_ONCE(ti->flags) &
+ (TIF_SYSCALL_EMU | TIF_SYSCALL_TRACE | TIF_SYSCALL_TRACEPOINT);
- /*
- * 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 & (TIF_SYSCALL_EMU | TIF_SYSCALL_TRACE)) {
+ 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))
@@ -3293,7 +3309,7 @@ long do_syscall_trace_enter(struct pt_regs *regs)
if (regs->gpr[0] >= NR_syscalls)
goto skip;
- if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
+ if (unlikely(cached_flags & TIF_SYSCALL_TRACEPOINT))
trace_sys_enter(regs, regs->gpr[0]);
#ifdef CONFIG_PPC64
--
ldv
next prev parent reply other threads:[~2018-12-03 3:20 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-16 11:17 [PATCH v2] powerpc/ptrace: replace ptrace_report_syscall() with a tracehook call Elvira Khabirova
2018-11-16 12:42 ` Michael Ellerman
2018-11-19 21:01 ` [PATCH v3] " Dmitry V. Levin
2018-11-21 21:17 ` Michael Ellerman
2018-12-03 3:18 ` Dmitry V. Levin [this message]
2018-12-07 1:19 ` [PATCH v4] " Dmitry V. Levin
2018-12-07 11:12 ` Michael Ellerman
2018-12-07 15:42 ` Dmitry V. Levin
2018-12-07 15:56 ` [PATCH v5] " Dmitry V. Levin
2018-12-07 18:52 ` [PATCH v6] " Dmitry V. Levin
2018-12-10 13:28 ` Oleg Nesterov
2018-12-10 13:36 ` Dmitry V. Levin
2018-12-16 17:28 ` [PATCH] powerpc/ptrace: cleanup do_syscall_trace_enter Dmitry V. Levin
2018-12-17 11:20 ` Michael Ellerman
2018-12-17 11:23 ` Dmitry V. Levin
2018-12-17 11:27 ` Oleg Nesterov
2018-12-22 9:54 ` Michael Ellerman
2018-12-11 13:45 ` [v5] powerpc/ptrace: replace ptrace_report_syscall() with a tracehook call Michael Ellerman
2018-12-07 16:34 ` [PATCH v4] " Oleg Nesterov
2018-12-07 18:42 ` Dmitry V. Levin
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