linux-kernel - [PATCH v2 4/7] riscv: Simplify text patching loops

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Date: Wed, 27 Mar 2024 09:04:43 -0700
From: Samuel Holland <samuel.holland@...ive.com>
To: Palmer Dabbelt <palmer@...belt.com>
Cc: Björn Töpel <bjorn@...osinc.com>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Samuel Holland <samuel.holland@...ive.com>
Subject: [PATCH v2 4/7] riscv: Simplify text patching loops

This reduces the number of variables and makes the code easier to parse.

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

Changes in v2:
 - Further simplify patch_insn_set()/patch_insn_write() loop conditions
 - Use min() instead of min_t() since both sides are unsigned long

 arch/riscv/kernel/patch.c | 37 +++++++++++++++++++++----------------
 1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
index 9a1bce1adf5a..0d1700d1934c 100644
--- a/arch/riscv/kernel/patch.c
+++ b/arch/riscv/kernel/patch.c
@@ -155,22 +155,24 @@ NOKPROBE_SYMBOL(__patch_insn_write);
 
 static int patch_insn_set(void *addr, u8 c, size_t len)
 {
-	size_t patched = 0;
 	size_t size;
-	int ret = 0;
+	int ret;
 
 	/*
 	 * __patch_insn_set() can only work on 2 pages at a time so call it in a
 	 * loop with len <= 2 * PAGE_SIZE.
 	 */
-	while (patched < len && !ret) {
-		size = min_t(size_t, PAGE_SIZE * 2 - offset_in_page(addr + patched), len - patched);
-		ret = __patch_insn_set(addr + patched, c, size);
-
-		patched += size;
+	while (len) {
+		size = min(len, PAGE_SIZE * 2 - offset_in_page(addr));
+		ret = __patch_insn_set(addr, c, size);
+		if (ret)
+			return ret;
+
+		addr += size;
+		len -= size;
 	}
 
-	return ret;
+	return 0;
 }
 NOKPROBE_SYMBOL(patch_insn_set);
 
@@ -190,22 +192,25 @@ NOKPROBE_SYMBOL(patch_text_set_nosync);
 
 int patch_insn_write(void *addr, const void *insn, size_t len)
 {
-	size_t patched = 0;
 	size_t size;
-	int ret = 0;
+	int ret;
 
 	/*
 	 * Copy the instructions to the destination address, two pages at a time
 	 * because __patch_insn_write() can only handle len <= 2 * PAGE_SIZE.
 	 */
-	while (patched < len && !ret) {
-		size = min_t(size_t, PAGE_SIZE * 2 - offset_in_page(addr + patched), len - patched);
-		ret = __patch_insn_write(addr + patched, insn + patched, size);
-
-		patched += size;
+	while (len) {
+		size = min(len, PAGE_SIZE * 2 - offset_in_page(addr));
+		ret = __patch_insn_write(addr, insn, size);
+		if (ret)
+			return ret;
+
+		addr += size;
+		insn += size;
+		len -= size;
 	}
 
-	return ret;
+	return 0;
 }
 NOKPROBE_SYMBOL(patch_insn_write);
 
-- 
2.43.1