linux-kernel - [PATCH V2] riscv/mm: Add handling for VM_FAULT_SIGSEGV in mm_fault

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Message-ID: <20240731084547.85380-1-qiaozhe@iscas.ac.cn>
Date: Wed, 31 Jul 2024 16:45:47 +0800
From: Zhe Qiao <qiaozhe@...as.ac.cn>
To: paul.walmsley@...ive.com,
	palmer@...belt.com,
	aou@...s.berkeley.edu,
	alexghiti@...osinc.com,
	surenb@...gle.com,
	akpm@...ux-foundation.org,
	wangkefeng.wang@...wei.com,
	qiaozhe@...as.ac.cn,
	willy@...radead.org
Cc: linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH V2] riscv/mm: Add handling for VM_FAULT_SIGSEGV in mm_fault_error()

Handle VM_FAULT_SIGSEGV in the page fault path so that we correctly
kill the process and we don't BUG() the kernel.

Fixes: 07037db5d479 ("RISC-V: Paging and MMU")
Signed-off-by: Zhe Qiao <qiaozhe@...as.ac.cn>
Reviewed-by: Alexandre Ghiti <alexghiti@...osinc.com>
---
v1->v2:
Modify commit message.
---
 arch/riscv/mm/fault.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index 5224f3733802..a9f2b4af8f3f 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -61,26 +61,27 @@ static inline void no_context(struct pt_regs *regs, unsigned long addr)
 
 static inline void mm_fault_error(struct pt_regs *regs, unsigned long addr, vm_fault_t fault)
 {
+	if (!user_mode(regs)) {
+		no_context(regs, addr);
+		return;
+	}
+
 	if (fault & VM_FAULT_OOM) {
 		/*
 		 * We ran out of memory, call the OOM killer, and return the userspace
 		 * (which will retry the fault, or kill us if we got oom-killed).
 		 */
-		if (!user_mode(regs)) {
-			no_context(regs, addr);
-			return;
-		}
 		pagefault_out_of_memory();
 		return;
 	} else if (fault & (VM_FAULT_SIGBUS | VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) {
 		/* Kernel mode? Handle exceptions or die */
-		if (!user_mode(regs)) {
-			no_context(regs, addr);
-			return;
-		}
 		do_trap(regs, SIGBUS, BUS_ADRERR, addr);
 		return;
+	} else if (fault & VM_FAULT_SIGSEGV) {
+		do_trap(regs, SIGSEGV, SEGV_MAPERR, addr);
+		return;
 	}
+
 	BUG();
 }
 
-- 
2.43.0