linux-kernel - [PATCH 1/2] LoongArch: uprobe: Remove user_{en,dis}able_single

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Message-ID: <20250513092116.25979-2-yangtiezhu@loongson.cn>
Date: Tue, 13 May 2025 17:21:15 +0800
From: Tiezhu Yang <yangtiezhu@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: loongarch@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] LoongArch: uprobe: Remove user_{en,dis}able_single_step()

When executing "perf probe" and "perf stat" test case about cryptographic
algorithm, the output shows that "Trace/breakpoint trap", this is because
it uses the software singlestep breakpoint for uprobe on LoongArch, so no
need to use the hardware singlestep, just remove the related function call
user_{en,dis}able_single_step() for uprobe on LoongArch.

How to reproduce:

Please make sure CONFIG_UPROBE_EVENTS is set and openssl supports algorithm
sm2, then execute the following command.

cd tools/perf && make
sudo ./perf probe -x /usr/lib64/libcrypto.so BN_mod_mul_montgomery
sudo ./perf stat -e probe_libcrypto:BN_mod_mul_montgomery openssl speed sm2

Fixes: 19bc6cb64092 ("LoongArch: Add uprobes support")
Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
---
 arch/loongarch/kernel/uprobes.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/loongarch/kernel/uprobes.c b/arch/loongarch/kernel/uprobes.c
index 87abc7137b73..0ab9d8d631c4 100644
--- a/arch/loongarch/kernel/uprobes.c
+++ b/arch/loongarch/kernel/uprobes.c
@@ -42,7 +42,6 @@ int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 	utask->autask.saved_trap_nr = current->thread.trap_nr;
 	current->thread.trap_nr = UPROBE_TRAP_NR;
 	instruction_pointer_set(regs, utask->xol_vaddr);
-	user_enable_single_step(current);
 
 	return 0;
 }
@@ -59,8 +58,6 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 	else
 		instruction_pointer_set(regs, utask->vaddr + LOONGARCH_INSN_SIZE);
 
-	user_disable_single_step(current);
-
 	return 0;
 }
 
@@ -70,7 +67,6 @@ void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 
 	current->thread.trap_nr = utask->autask.saved_trap_nr;
 	instruction_pointer_set(regs, utask->vaddr);
-	user_disable_single_step(current);
 }
 
 bool arch_uprobe_xol_was_trapped(struct task_struct *t)
-- 
2.42.0