kernel: Binary code patches on x86.

This will be used to support SMAP. Sponsored-by: https://liberapay.com/korli
2018-01-14 13:20:38 +01:00
parent e6168b4ffe
commit a2021292d4
5 changed files with 110 additions and 0 deletions
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2018, Jérôme Duval, [email protected].
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef _KERNEL_ARCH_x86_ALTCODEPATCH_H
+#define _KERNEL_ARCH_x86_ALTCODEPATCH_H
+
+
+#include <arch/x86/arch_kernel.h>
+
+
+#define ASM_NOP1	.byte 0x90
+#define ASM_NOP2	.byte 0x66, 0x90
+#define ASM_NOP3	.byte 0x0f, 0x1f, 0x00
+#define ASM_NOP4	.byte 0x0f, 0x1f, 0x40, 0x00
+#define ASM_NOP5	.byte 0x0f, 0x1f, 0x44, 0x00, 0x00
+#define ASM_NOP6	.byte 0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00
+#define ASM_NOP7	.byte 0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00
+#define ASM_NOP8	.byte 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00
+#define ASM_NOP9	.byte 0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00
+
+
+#ifdef _ASSEMBLER
+
+#define CODEPATCH_START	990:
+#define CODEPATCH_END(tag)	991:	\
+	.pushsection	.altcodepatch, "a"	;	\
+	.long			(990b - KERNEL_LOAD_BASE)	;	\
+	.short			(991b - 990b)		;	\
+	.short			tag				;	\
+	.popsection
+
+#else
+
+#define _STRINGIFY(x...)	#x
+#define STRINGIFY(x...)		_STRINGIFY(x)
+
+#define CODEPATCH_START	"990:	\n"
+#define CODEPATCH_END(tag)	"991:	\n"	\
+	".pushsection	.altcodepatch, \"a\"	\n" \
+	".long			(990b - " STRINGIFY(KERNEL_LOAD_BASE) ")	\n" \
+	".short			(991b - 990b)		\n" \
+	".short			" STRINGIFY(tag)	"	\n" \
+	".popsection"
+
+void arch_altcodepatch_replace(uint16 tag, void* newcodepatch, size_t length);
+
+
+#endif
+
+#endif	/* _KERNEL_ARCH_x86_ALTCODEPATCH_H */