From e6e65be0752fd7c45d03d8f58d3e53463e7fa9d7 Mon Sep 17 00:00:00 2001 From: Tiezhu Yang Date: Tue, 10 Feb 2026 19:31:17 +0800 Subject: [PATCH] LoongArch: Disable instrumentation for setup_ptwalker() [ Upstream commit 7cb37af61f09c9cfd90c43c9275307c16320cbf2 ] According to Documentation/dev-tools/kasan.rst, software KASAN modes use compiler instrumentation to insert validity checks. Such instrumentation might be incompatible with some parts of the kernel, and therefore needs to be disabled, just use the attribute __no_sanitize_address to disable instrumentation for the low level function setup_ptwalker(). Otherwise bringing up the secondary CPUs failed when CONFIG_KASAN is set (especially when PTW is enabled), here are the call chains: smpboot_entry() start_secondary() cpu_probe() per_cpu_trap_init() tlb_init() setup_tlb_handler() setup_ptwalker() The reason is the PGD registers are configured in setup_ptwalker(), but KASAN instrumentation may cause TLB exceptions before that. Cc: stable@vger.kernel.org Signed-off-by: Tiezhu Yang Signed-off-by: Huacai Chen Signed-off-by: Sasha Levin --- arch/loongarch/mm/tlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/loongarch/mm/tlb.c b/arch/loongarch/mm/tlb.c index 3b427b319db2..f46c15d6e7ea 100644 --- a/arch/loongarch/mm/tlb.c +++ b/arch/loongarch/mm/tlb.c @@ -202,7 +202,7 @@ void __update_tlb(struct vm_area_struct *vma, unsigned long address, pte_t *ptep local_irq_restore(flags); } -static void setup_ptwalker(void) +static void __no_sanitize_address setup_ptwalker(void) { unsigned long pwctl0, pwctl1; unsigned long pgd_i = 0, pgd_w = 0;