ARM: 7332/1: extract out code patch function from kprobes

Extract out the code patching code from kprobes so that it can be used
from the jump label code.  Additionally, the separated code:

 - Uses the IS_ENABLED() macros instead of the #ifdefs for THUMB2
   support

 - Unifies the two separate functions in kprobes, providing one function
   that uses stop_machine() internally, and one that can be called from
   stop_machine() directly

 - Patches the text on all CPUs only on processors requiring software
   broadcasting of cache operations

Acked-by: Jon Medhurst <tixy@yxit.co.uk>
Tested-by: Jon Medhurst <tixy@yxit.co.uk>
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 75 insertions, 0 deletions

diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
new file mode 100644
index 000000000000..07314af47733
--- /dev/null
+++ b/arch/arm/kernel/patch.c
@@ -0,0 +1,75 @@
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/stop_machine.h>
+
+#include <asm/cacheflush.h>
+#include <asm/smp_plat.h>
+#include <asm/opcodes.h>
+
+#include "patch.h"
+
+struct patch {
+	void *addr;
+	unsigned int insn;
+};
+
+void __kprobes __patch_text(void *addr, unsigned int insn)
+{
+	bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL);
+	int size;
+
+	if (thumb2 && __opcode_is_thumb16(insn)) {
+		*(u16 *)addr = __opcode_to_mem_thumb16(insn);
+		size = sizeof(u16);
+	} else if (thumb2 && ((uintptr_t)addr & 2)) {
+		u16 first = __opcode_thumb32_first(insn);
+		u16 second = __opcode_thumb32_second(insn);
+		u16 *addrh = addr;
+
+		addrh[0] = __opcode_to_mem_thumb16(first);
+		addrh[1] = __opcode_to_mem_thumb16(second);
+
+		size = sizeof(u32);
+	} else {
+		if (thumb2)
+			insn = __opcode_to_mem_thumb32(insn);
+		else
+			insn = __opcode_to_mem_arm(insn);
+
+		*(u32 *)addr = insn;
+		size = sizeof(u32);
+	}
+
+	flush_icache_range((uintptr_t)(addr),
+			   (uintptr_t)(addr) + size);
+}
+
+static int __kprobes patch_text_stop_machine(void *data)
+{
+	struct patch *patch = data;
+
+	__patch_text(patch->addr, patch->insn);
+
+	return 0;
+}
+
+void __kprobes patch_text(void *addr, unsigned int insn)
+{
+	struct patch patch = {
+		.addr = addr,
+		.insn = insn,
+	};
+
+	if (cache_ops_need_broadcast()) {
+		stop_machine(patch_text_stop_machine, &patch, cpu_online_mask);
+	} else {
+		bool straddles_word = IS_ENABLED(CONFIG_THUMB2_KERNEL)
+				      && __opcode_is_thumb32(insn)
+				      && ((uintptr_t)addr & 2);
+
+		if (straddles_word)
+			stop_machine(patch_text_stop_machine, &patch, NULL);
+		else
+			__patch_text(addr, insn);
+	}
+}