KSP: added variable sized patch support

Signed-off-by: Oliver Pinter <[email protected]>
opntr · Aug 14, 2014 · b29c263 · b29c263
1 parent 5be2b1d
commit b29c263
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Showing 5 changed files with 79 additions and 4 deletions.
diff --git a/sys/kern/kern_selfpatch.c b/sys/kern/kern_selfpatch.c
@@ -73,6 +73,7 @@ static void lf_open_kernel_text(struct lf_selfpatch *p);
 static void lf_close_kernel_text(struct lf_selfpatch *p);
 static void lf_open_module_text(struct lf_selfpatch *p);
 static void lf_close_module_text(struct lf_selfpatch *p);
+static void lf_pad_with_nop(struct lf_selfpatch *p);
 
 bool
 lf_selfpatch_patch_needed(struct lf_selfpatch *p)
@@ -194,13 +195,13 @@ lf_selfpatch_apply(linker_file_t lf, struct lf_selfpatch *p, int mod)
 	 * replace the instructions
 	 */
 	memcpy(p->patchable, p->patch, p->patchable_size);
+	lf_pad_with_nop(p);
 
 	if (mod == KSP_MODULE)
 		lf_close_module_text(p);
 	else
 		lf_close_kernel_text(p);
 
-
 	DBG("patched.\n");
 
 	return (0);
@@ -302,6 +303,33 @@ lf_close_module_text(struct lf_selfpatch *p)
 	DBG("caches flushed.\n");
 }
 
+
+static void
+lf_pad_with_nop(struct lf_selfpatch *p)
+{
+	int i, rem;
+	char *patchable;
+
+	if (p->patch_size == p->patchable_size)
+		return;
+
+	if (p->patch_size > p->patchable_size)
+		panic("%s: patch_size > patchable_size", __func__);
+
+	rem = p->patchable_size - p->patch_size;
+	patchable = p->patchable + p->patch_size;
+
+	for (i = rem / KSP_MAX_NOPLEN; i > 0; i -= KSP_MAX_NOPLEN) {
+		memcpy(patchable,
+		    selfpatch_nop_table[KSP_MAX_NOPLEN],
+		    KSP_MAX_NOPLEN);
+		patchable += KSP_MAX_NOPLEN;
+	}
+
+	rem %= KSP_MAX_NOPLEN;
+	memcpy(patchable, selfpatch_nop_table[rem], rem);
+}
+
 #ifdef KSP_DEBUG
 __noinline void
 lf_selfpatch_selftest(void)

diff --git a/sys/sys/selfpatch.h b/sys/sys/selfpatch.h
@@ -60,7 +60,7 @@ typedef struct lf_selfpatch {
 	char	*comment;
 } lf_selfpatch_t;
 
-extern char *selfpatch_nop_table[];
+extern const char *selfpatch_nop_table[];
 
 int lf_selfpatch(linker_file_t lf, int mod);
 int lf_selfpatch_apply(linker_file_t lf, struct lf_selfpatch *patch, int mod);

diff --git a/sys/x86/include/selfpatch-asmacros.h b/sys/x86/include/selfpatch-asmacros.h
@@ -86,6 +86,7 @@
 #define	KSP_INSTR_NOP8_C	KSP_INSTR_INTEL_NOP8_C
 #define	KSP_INSTR_NOP9_C	KSP_INSTR_INTEL_NOP9_C
 
+#define	KSP_MAX_NOPLEN		9
 
 #define KSP_INSTR_XSAVE_XSAVEOPT(_ARG)					\
 	0723: 								\

diff --git a/sys/x86/include/selfpatch-machdep.h b/sys/x86/include/selfpatch-machdep.h
@@ -31,8 +31,6 @@
 
 struct lf_selfpatch;
 
-extern char *md_selfpatch_nop_table[];
-
 bool lf_selfpatch_patch_needed(struct lf_selfpatch *p);
 
 #endif /* __X86_SELFPATH_MACHDEP_H__ */
diff --git a/sys/x86/x86/selfpatch_machdep.c b/sys/x86/x86/selfpatch_machdep.c
@@ -53,3 +53,51 @@ const struct ksp_selector_entry ksp_selector_table[] = {
 	KSP_SELECTOR_END
 };
 
+/*
+ * assembly NOP store
+ */
+extern const char       nop1;
+extern const char       nop2;
+extern const char       nop3;
+extern const char       nop4;
+extern const char       nop5;
+extern const char       nop6;
+extern const char       nop7;
+extern const char       nop8;
+extern const char       nop9;
+
+const char *selfpatch_nop_table[] = {
+	[0] = (const char *)NULL,
+	[1] = (const char *)&nop1,
+	[2] = (const char *)&nop2,
+	[3] = (const char *)&nop3,
+	[4] = (const char *)&nop4,
+	[5] = (const char *)&nop5,
+	[6] = (const char *)&nop6,
+	[7] = (const char *)&nop7,
+	[8] = (const char *)&nop8,
+	[9] = (const char *)&nop9
+};
+
+__asm(
+"nop1:                          \n"
+"      " KSP_INSTR_NOP1_C "	\n"
+"nop2:                          \n"
+"      " KSP_INSTR_NOP2_C "	\n"
+"nop3:                          \n"
+"      " KSP_INSTR_NOP3_C "	\n"
+"nop4:                          \n"
+"      " KSP_INSTR_NOP4_C "	\n"
+"nop5:                          \n"
+"      " KSP_INSTR_NOP5_C "	\n"
+"nop6:                          \n"
+"      " KSP_INSTR_NOP6_C "	\n"
+"nop7:                          \n"
+"      " KSP_INSTR_NOP7_C "	\n"
+"nop8:                          \n"
+"      " KSP_INSTR_NOP8_C "	\n"
+"nop9:                          \n"
+"      " KSP_INSTR_NOP9_C "	\n"
+"	.p2align 4,0x90		\n"
+);
+