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From:   Nicholas Miehlbradt <nicholas@linux.ibm.com>
To:     glider@google.com, elver@google.com, dvyukov@google.com,
        akpm@linux-foundation.org, mpe@ellerman.id.au, npiggin@gmail.com,
        christophe.leroy@csgroup.eu
Cc:     linux-mm@kvack.org, kasan-dev@googlegroups.com, iii@linux.ibm.com,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        Nicholas Miehlbradt <nicholas@linux.ibm.com>
Subject: [PATCH 09/13] powerpc: Disable KMSAN checks on functions which walk the stack
Date:   Thu, 14 Dec 2023 05:55:35 +0000
Message-Id: <20231214055539.9420-10-nicholas@linux.ibm.com>
In-Reply-To: <20231214055539.9420-1-nicholas@linux.ibm.com>
References: <20231214055539.9420-1-nicholas@linux.ibm.com>
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Functions which walk the stack read parts of the stack which cannot be
instrumented by KMSAN e.g. the backchain. Disable KMSAN sanitization of
these functions to prevent false positives.

Signed-off-by: Nicholas Miehlbradt <nicholas@linux.ibm.com>
---
 arch/powerpc/kernel/process.c    |  6 +++---
 arch/powerpc/kernel/stacktrace.c | 10 ++++++----
 arch/powerpc/perf/callchain.c    |  2 +-
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 392404688cec..3dc88143c3b2 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -2276,9 +2276,9 @@ static bool empty_user_regs(struct pt_regs *regs, struct task_struct *tsk)
 
 static int kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
 
-void __no_sanitize_address show_stack(struct task_struct *tsk,
-				      unsigned long *stack,
-				      const char *loglvl)
+void __no_sanitize_address __no_kmsan_checks show_stack(struct task_struct *tsk,
+							unsigned long *stack,
+							const char *loglvl)
 {
 	unsigned long sp, ip, lr, newsp;
 	int count = 0;
diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c
index e6a958a5da27..369b8b2a1bcd 100644
--- a/arch/powerpc/kernel/stacktrace.c
+++ b/arch/powerpc/kernel/stacktrace.c
@@ -24,8 +24,9 @@
 
 #include <asm/paca.h>
 
-void __no_sanitize_address arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
-					   struct task_struct *task, struct pt_regs *regs)
+void __no_sanitize_address __no_kmsan_checks
+	arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
+			struct task_struct *task, struct pt_regs *regs)
 {
 	unsigned long sp;
 
@@ -62,8 +63,9 @@ void __no_sanitize_address arch_stack_walk(stack_trace_consume_fn consume_entry,
  *
  * If the task is not 'current', the caller *must* ensure the task is inactive.
  */
-int __no_sanitize_address arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
-						   void *cookie, struct task_struct *task)
+int __no_sanitize_address __no_kmsan_checks
+	arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, void *cookie,
+				 struct task_struct *task)
 {
 	unsigned long sp;
 	unsigned long newsp;
diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
index 6b4434dd0ff3..c7610b38e9b8 100644
--- a/arch/powerpc/perf/callchain.c
+++ b/arch/powerpc/perf/callchain.c
@@ -40,7 +40,7 @@ static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
 	return 0;
 }
 
-void __no_sanitize_address
+void __no_sanitize_address __no_kmsan_checks
 perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
 {
 	unsigned long sp, next_sp;
-- 
2.40.1