linux-kernel - [PATCH 1/7] riscv: jump_label: Batch icache maintenance

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Message-ID: <20240212025529.1971876-2-samuel.holland@sifive.com>
Date: Sun, 11 Feb 2024 18:55:12 -0800
From: Samuel Holland <samuel.holland@...ive.com>
To: Palmer Dabbelt <palmer@...belt.com>
Cc: linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Samuel Holland <samuel.holland@...ive.com>,
	Ard Biesheuvel <ardb@...nel.org>,
	Jason Baron <jbaron@...mai.com>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH 1/7] riscv: jump_label: Batch icache maintenance

Switch to the batched version of the jump label update functions so
instruction cache maintenance is deferred until the end of the update.

Signed-off-by: Samuel Holland <samuel.holland@...ive.com>
---

 arch/riscv/include/asm/jump_label.h |  2 ++
 arch/riscv/include/asm/patch.h      |  1 +
 arch/riscv/kernel/jump_label.c      | 16 ++++++++++++----
 arch/riscv/kernel/patch.c           |  2 +-
 4 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
index 4a35d787c019..6290b26f4a14 100644
--- a/arch/riscv/include/asm/jump_label.h
+++ b/arch/riscv/include/asm/jump_label.h
@@ -12,6 +12,8 @@
 #include <linux/types.h>
 #include <asm/asm.h>
 
+#define HAVE_JUMP_LABEL_BATCH
+
 #define JUMP_LABEL_NOP_SIZE 4
 
 static __always_inline bool arch_static_branch(struct static_key * const key,
diff --git a/arch/riscv/include/asm/patch.h b/arch/riscv/include/asm/patch.h
index e88b52d39eac..9f5d6e14c405 100644
--- a/arch/riscv/include/asm/patch.h
+++ b/arch/riscv/include/asm/patch.h
@@ -6,6 +6,7 @@
 #ifndef _ASM_RISCV_PATCH_H
 #define _ASM_RISCV_PATCH_H
 
+int patch_insn_write(void *addr, const void *insn, size_t len);
 int patch_text_nosync(void *addr, const void *insns, size_t len);
 int patch_text_set_nosync(void *addr, u8 c, size_t len);
 int patch_text(void *addr, u32 *insns, int ninsns);
diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
index e6694759dbd0..11ad789c60c6 100644
--- a/arch/riscv/kernel/jump_label.c
+++ b/arch/riscv/kernel/jump_label.c
@@ -9,13 +9,14 @@
 #include <linux/memory.h>
 #include <linux/mutex.h>
 #include <asm/bug.h>
+#include <asm/cacheflush.h>
 #include <asm/patch.h>
 
 #define RISCV_INSN_NOP 0x00000013U
 #define RISCV_INSN_JAL 0x0000006fU
 
-void arch_jump_label_transform(struct jump_entry *entry,
-			       enum jump_label_type type)
+bool arch_jump_label_transform_queue(struct jump_entry *entry,
+				     enum jump_label_type type)
 {
 	void *addr = (void *)jump_entry_code(entry);
 	u32 insn;
@@ -24,7 +25,7 @@ void arch_jump_label_transform(struct jump_entry *entry,
 		long offset = jump_entry_target(entry) - jump_entry_code(entry);
 
 		if (WARN_ON(offset & 1 || offset < -524288 || offset >= 524288))
-			return;
+			return true;
 
 		insn = RISCV_INSN_JAL |
 			(((u32)offset & GENMASK(19, 12)) << (12 - 12)) |
@@ -36,6 +37,13 @@ void arch_jump_label_transform(struct jump_entry *entry,
 	}
 
 	mutex_lock(&text_mutex);
-	patch_text_nosync(addr, &insn, sizeof(insn));
+	patch_insn_write(addr, &insn, sizeof(insn));
 	mutex_unlock(&text_mutex);
+
+	return true;
+}
+
+void arch_jump_label_transform_apply(void)
+{
+	flush_icache_all();
 }
diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
index 37e87fdcf6a0..bccd9ed04a05 100644
--- a/arch/riscv/kernel/patch.c
+++ b/arch/riscv/kernel/patch.c
@@ -188,7 +188,7 @@ int patch_text_set_nosync(void *addr, u8 c, size_t len)
 }
 NOKPROBE_SYMBOL(patch_text_set_nosync);
 
-static int patch_insn_write(void *addr, const void *insn, size_t len)
+int patch_insn_write(void *addr, const void *insn, size_t len)
 {
 	size_t patched = 0;
 	size_t size;
-- 
2.43.0