linux-kernel - [PATCH 09/13] powerpc: Disable KMSAN checks on functions which walk the stack

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Message-Id: <20231214055539.9420-10-nicholas@linux.ibm.com>
Date:   Thu, 14 Dec 2023 05:55:35 +0000
From:   Nicholas Miehlbradt <nicholas@...ux.ibm.com>
To:     glider@...gle.com, elver@...gle.com, dvyukov@...gle.com,
        akpm@...ux-foundation.org, mpe@...erman.id.au, npiggin@...il.com,
        christophe.leroy@...roup.eu
Cc:     linux-mm@...ck.org, kasan-dev@...glegroups.com, iii@...ux.ibm.com,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Nicholas Miehlbradt <nicholas@...ux.ibm.com>
Subject: [PATCH 09/13] powerpc: Disable KMSAN checks on functions which walk the stack

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@...ux.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