linux-kernel - [PATCH] LoongArch: Handle newly added llsc instructions for probes

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Message-ID: <20250826063956.6950-1-yangtiezhu@loongson.cn>
Date: Tue, 26 Aug 2025 14:39:56 +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] LoongArch: Handle newly added llsc instructions for probes

The atomic instructions sc.q, llacq.{w/d}, screl.{w/d} were newly added
in the LoongArch Reference Manual v1.10, it is necessary to handle them
in insns_not_supported() to avoid putting a breakpoint in the middle of
a ll/sc atomic sequence, otherwise it will loop forever for kprobes and
uprobes.

Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
---
 arch/loongarch/include/asm/inst.h |  5 +++++
 arch/loongarch/kernel/inst.c      | 12 ++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
index 277d2140676b..55e64a12a124 100644
--- a/arch/loongarch/include/asm/inst.h
+++ b/arch/loongarch/include/asm/inst.h
@@ -77,6 +77,10 @@ enum reg2_op {
 	iocsrwrh_op     = 0x19205,
 	iocsrwrw_op     = 0x19206,
 	iocsrwrd_op     = 0x19207,
+	llacqw_op	= 0xe15e0,
+	screlw_op	= 0xe15e1,
+	llacqd_op	= 0xe15e2,
+	screld_op	= 0xe15e3,
 };
 
 enum reg2i5_op {
@@ -189,6 +193,7 @@ enum reg3_op {
 	fldxd_op	= 0x7068,
 	fstxs_op	= 0x7070,
 	fstxd_op	= 0x7078,
+	scq_op		= 0x70ae,
 	amswapw_op	= 0x70c0,
 	amswapd_op	= 0x70c1,
 	amaddw_op	= 0x70c2,
diff --git a/arch/loongarch/kernel/inst.c b/arch/loongarch/kernel/inst.c
index 72ecfed29d55..4026edea9bdd 100644
--- a/arch/loongarch/kernel/inst.c
+++ b/arch/loongarch/kernel/inst.c
@@ -141,6 +141,18 @@ bool insns_not_supported(union loongarch_instruction insn)
 	case amswapw_op ... ammindbdu_op:
 		pr_notice("atomic memory access instructions are not supported\n");
 		return true;
+	case scq_op:
+		pr_notice("sc.q instruction is not supported\n");
+		return true;
+	}
+
+	switch (insn.reg2_format.opcode) {
+	case llacqw_op:
+	case llacqd_op:
+	case screlw_op:
+	case screld_op:
+		pr_notice("llacq and screl instructions are not supported\n");
+		return true;
 	}
 
 	switch (insn.reg2i14_format.opcode) {
-- 
2.42.0