linux-kernel - [PATCH] riscv: traps: handle uprobe event in software-check exception

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Message-Id: <20250314092614.27372-1-zong.li@sifive.com>
Date: Fri, 14 Mar 2025 17:26:14 +0800
From: Zong Li <zong.li@...ive.com>
To: paul.walmsley@...ive.com,
	palmer@...belt.com,
	aou@...s.berkeley.edu,
	debug@...osinc.com,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc: Zong Li <zong.li@...ive.com>
Subject: [PATCH] riscv: traps: handle uprobe event in software-check exception

Handle the uprobe event first before handling the CFI violation in
software-check exception handler. Because when the landing pad is
activated, if the uprobe point is set at the lpad instruction at
the beginning of a function, the system triggers a software-check
exception instead of an ebreak exception due to the exception
priority, then uprobe can't work successfully.

Co-developed-by: Deepak Gupta <debug@...osinc.com>
Signed-off-by: Deepak Gupta <debug@...osinc.com>
Signed-off-by: Zong Li <zong.li@...ive.com>
---

This patch is based on top of the following series
[PATCH v11 00/27] riscv control-flow integrity for usermode

 arch/riscv/kernel/traps.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 3f7709f4595a..ef5a92111ee1 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -386,9 +386,12 @@ asmlinkage __visible __trap_section void do_trap_software_check(struct pt_regs *
 	if (user_mode(regs)) {
 		irqentry_enter_from_user_mode(regs);
 
-		/* not a cfi violation, then merge into flow of unknown trap handler */
-		if (!handle_user_cfi_violation(regs))
-			do_trap_unknown(regs);
+		/* handle uprobe event frist */
+		if (!probe_breakpoint_handler(regs)) {
+			/* not a cfi violation, then merge into flow of unknown trap handler */
+			if (!handle_user_cfi_violation(regs))
+				do_trap_unknown(regs);
+		}
 
 		irqentry_exit_to_user_mode(regs);
 	} else {
-- 
2.17.1