linux-kernel - [PATCH 3/3] mm/memory: Use exception ip to search exception tables

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Message-Id: <20240201-exception_ip-v1-3-aa26ab3ee0b5@flygoat.com>
Date: Thu, 01 Feb 2024 15:46:29 +0000
From: Jiaxun Yang <jiaxun.yang@...goat.com>
To: Oleg Nesterov <oleg@...hat.com>, 
 Thomas Bogendoerfer <tsbogend@...ha.franken.de>, 
 Andrew Morton <akpm@...ux-foundation.org>, 
 Ben Hutchings <ben@...adent.org.uk>
Cc: linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-mips@...r.kernel.org, linux-mm@...ck.org, 
 Jiaxun Yang <jiaxun.yang@...goat.com>, Xi Ruoyao <xry111@...111.site>, 
 Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 3/3] mm/memory: Use exception ip to search exception tables

On architectures with delay slot, instruction_pointer() may differ
from where exception was triggered.

Use exception_ip we just introduced to search exception tables to
get rid of the problem.

Fixes: 4bce37a68ff8 ("mips/mm: Convert to using lock_mm_and_find_vma()")
Reported-by: Xi Ruoyao <xry111@...111.site>
Link: https://lore.kernel.org/r/75e9fd7b08562ad9b456a5bdaacb7cc220311cc9.camel@xry111.site/
Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
---
 mm/memory.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 8d14ba440929..49433612444a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5481,7 +5481,7 @@ static inline bool get_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs
 		return true;
 
 	if (regs && !user_mode(regs)) {
-		unsigned long ip = instruction_pointer(regs);
+		unsigned long ip = exception_ip(regs);
 		if (!search_exception_tables(ip))
 			return false;
 	}
@@ -5506,7 +5506,7 @@ static inline bool upgrade_mmap_lock_carefully(struct mm_struct *mm, struct pt_r
 {
 	mmap_read_unlock(mm);
 	if (regs && !user_mode(regs)) {
-		unsigned long ip = instruction_pointer(regs);
+		unsigned long ip = exception_ip(regs);
 		if (!search_exception_tables(ip))
 			return false;
 	}

-- 
2.43.0