linux-kernel - [PATCH v6 16/18] arm64: Unify software tag-based KASAN inline recovery path

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Message-ID: <0a21096d806eafa679798b9844ec33bf8a5499a4.1761763681.git.m.wieczorretman@pm.me>
Date: Wed, 29 Oct 2025 20:10:26 +0000
From: Maciej Wieczor-Retman <m.wieczorretman@...me>
To: xin@...or.com, peterz@...radead.org, kaleshsingh@...gle.com, kbingham@...nel.org, akpm@...ux-foundation.org, nathan@...nel.org, ryabinin.a.a@...il.com, dave.hansen@...ux.intel.com, bp@...en8.de, morbo@...gle.com, jeremy.linton@....com, smostafa@...gle.com, kees@...nel.org, baohua@...nel.org, vbabka@...e.cz, justinstitt@...gle.com, wangkefeng.wang@...wei.com, leitao@...ian.org, jan.kiszka@...mens.com, fujita.tomonori@...il.com, hpa@...or.com, urezki@...il.com, ubizjak@...il.com, ada.coupriediaz@....com, nick.desaulniers+lkml@...il.com, ojeda@...nel.org, brgerst@...il.com, elver@...gle.com, pankaj.gupta@....com, glider@...gle.com, mark.rutland@....com, trintaeoitogc@...il.com, jpoimboe@...nel.org, thuth@...hat.com, pasha.tatashin@...een.com, dvyukov@...gle.com, jhubbard@...dia.com, catalin.marinas@....com, yeoreum.yun@....com, mhocko@...e.com, lorenzo.stoakes@...cle.com, samuel.holland@...ive.com, vincenzo.frascino@....com, bigeasy@...utronix.de, surenb@...gle.com,
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Subject: [PATCH v6 16/18] arm64: Unify software tag-based KASAN inline recovery path

From: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>

To avoid having a copy of a long comment explaining the intricacies of
the inline KASAN recovery system and issues for every architecture that
uses the software tag-based mode, a unified kasan_die_unless_recover()
function was added.

Use kasan_die_unless_recover() in the kasan brk handler to cleanup the
long comment, that's kept in the non-arch KASAN code.

Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
Acked-by: Catalin Marinas <catalin.marinas@....com>
---
Changelog v6:
- Add Catalin's Acked-by tag.

Changelog v5:
- Split arm64 portion of patch 13/18 into this one. (Peter Zijlstra)

 arch/arm64/kernel/traps.c | 17 +----------------
 1 file changed, 1 insertion(+), 16 deletions(-)

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 681939ef5d16..b1efc11c3b5a 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -1071,22 +1071,7 @@ int kasan_brk_handler(struct pt_regs *regs, unsigned long esr)
 
 	kasan_report(addr, size, write, pc);
 
-	/*
-	 * The instrumentation allows to control whether we can proceed after
-	 * a crash was detected. This is done by passing the -recover flag to
-	 * the compiler. Disabling recovery allows to generate more compact
-	 * code.
-	 *
-	 * Unfortunately disabling recovery doesn't work for the kernel right
-	 * now. KASAN reporting is disabled in some contexts (for example when
-	 * the allocator accesses slab object metadata; this is controlled by
-	 * current->kasan_depth). All these accesses are detected by the tool,
-	 * even though the reports for them are not printed.
-	 *
-	 * This is something that might be fixed at some point in the future.
-	 */
-	if (!recover)
-		die("Oops - KASAN", regs, esr);
+	kasan_die_unless_recover(recover, "Oops - KASAN", regs, esr, die);
 
 	/* If thread survives, skip over the brk instruction and continue: */
 	arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
-- 
2.51.0