linux-kernel - [PATCH v3] powerpc/ptrace: replace ptrace_report

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Date:   Tue, 20 Nov 2018 00:01:39 +0300
From:   "Dmitry V. Levin" <ldv@...linux.org>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>
Cc:     Oleg Nesterov <oleg@...hat.com>, Breno Leitao <leitao@...ian.org>,
        Andy Lutomirski <luto@...nel.org>,
        Eugene Syromyatnikov <esyr@...hat.com>,
        Elvira Khabirova <lineprinter@...linux.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3] powerpc/ptrace: replace ptrace_report_syscall() with a
 tracehook call

From: Elvira Khabirova <lineprinter@...linux.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@...linux.org>
Fixes: 5521eb4bca2d ("powerpc/ptrace: Add support for PTRACE_SYSEMU")
Signed-off-by: Elvira Khabirova <lineprinter@...linux.org>
Signed-off-by: Dmitry V. Levin <ldv@...linux.org>
---

v3: add a descriptive comment
v2: explicitly ignore tracehook_report_syscall_entry() return code

 arch/powerpc/kernel/ptrace.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index afb819f4ca68..e84220d91bbd 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -3266,7 +3266,12 @@ long do_syscall_trace_enter(struct pt_regs *regs)
 	user_exit();
 
 	if (test_thread_flag(TIF_SYSCALL_EMU)) {
-		ptrace_report_syscall(regs);
+		/*
+		 * 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.
+		 */
+		(void) tracehook_report_syscall_entry(regs);
 		/*
 		 * Returning -1 will skip the syscall execution. We want to
 		 * avoid clobbering any register also, thus, not 'gotoing'
-- 
ldv