From 082ad81ab0b269841c4d4a094d9692a9e681d38f Mon Sep 17 00:00:00 2001
From: Zhipeng Xie <xiezhipeng1@huawei.com>
Date: Wed, 26 Feb 2020 20:43:34 -0500
Subject: [PATCH 12/38] livepatch-patch-hook: support force enable/disable

we use force to indicate function which bypass stack check

Signed-off-by: Zhipeng Xie <xiezhipeng1@huawei.com>
---
 kmod/patch/kpatch-patch.h         |  1 +
 kmod/patch/livepatch-patch-hook.c | 17 +++++++++++++++++
 kpatch-build/kpatch-build         | 17 +++++++++++++++--
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/kmod/patch/kpatch-patch.h b/kmod/patch/kpatch-patch.h
index 9df7818..6e39364 100644
--- a/kmod/patch/kpatch-patch.h
+++ b/kmod/patch/kpatch-patch.h
@@ -64,4 +64,5 @@ struct kpatch_post_unpatch_callback {
 	char *objname;
 };
 
+extern unsigned long __kpatch_force_funcs[], __kpatch_force_funcs_end[];
 #endif /* _KPATCH_PATCH_H_ */
diff --git a/kmod/patch/livepatch-patch-hook.c b/kmod/patch/livepatch-patch-hook.c
index b578ef3..71439d9 100644
--- a/kmod/patch/livepatch-patch-hook.c
+++ b/kmod/patch/livepatch-patch-hook.c
@@ -432,6 +432,16 @@ extern struct kpatch_patch_func __kpatch_funcs[], __kpatch_funcs_end[];
 extern struct kpatch_patch_dynrela __kpatch_dynrelas[], __kpatch_dynrelas_end[];
 #endif
 
+static int patch_is_func_forced(unsigned long addr)
+{
+	unsigned long *a;
+
+	for (a = __kpatch_force_funcs; a < __kpatch_force_funcs_end; a++)
+		if (*a == addr)
+			return 1;
+	return 0;
+}
+
 static int __init patch_init(void)
 {
 	struct kpatch_patch_func *kfunc;
@@ -520,6 +530,13 @@ static int __init patch_init(void)
 			lfunc = &lfuncs[j];
 			lfunc->old_name = func->kfunc->name;
 			lfunc->new_func = (void *)func->kfunc->new_addr;
+#if defined(__KLP_SUPPORT_FORCE__)
+#ifdef __ALL_FORCE__
+			lfunc->force = 1;
+#else
+			lfunc->force = patch_is_func_forced(func->kfunc->new_addr);
+#endif
+#endif
 #ifdef HAVE_SYMPOS
 			lfunc->old_sympos = func->kfunc->sympos;
 #else
diff --git a/kpatch-build/kpatch-build b/kpatch-build/kpatch-build
index 0567523..39f8050 100755
--- a/kpatch-build/kpatch-build
+++ b/kpatch-build/kpatch-build
@@ -372,7 +372,7 @@ find_special_section_data() {
 	# shellcheck disable=SC2086
 	SPECIAL_VARS="$("$READELF" -wi "$VMLINUX" |
 		gawk --non-decimal-data $AWK_OPTIONS '
-		BEGIN { a = b = e = f = i = j = o = p = s = 0 }
+		BEGIN { a = b = e = f = i = j = o = p = s = c = d = 0 }
 
 		# Set state if name matches
 		check_a && a == 0 && /DW_AT_name.* alt_instr[[:space:]]*$/ {a = 1; next}
@@ -384,6 +384,7 @@ find_special_section_data() {
 		check_o && o == 0 && /DW_AT_name.* orc_entry[[:space:]]*$/ {o = 1; next}
 		check_p && p == 0 && /DW_AT_name.* paravirt_patch_site[[:space:]]*$/ {p = 1; next}
 		check_s && s == 0 && /DW_AT_name.* static_call_site[[:space:]]*$/ {s = 1; next}
+		c == 0 && /DW_AT_name.* klp_func[[:space:]]*$/ {c = 1; next}
 
 		# Reset state unless this abbrev describes the struct size
 		a == 1 && !/DW_AT_byte_size/ { a = 0; next }
@@ -395,6 +396,8 @@ find_special_section_data() {
 		o == 1 && !/DW_AT_byte_size/ { o = 0; next }
 		p == 1 && !/DW_AT_byte_size/ { p = 0; next }
 		s == 1 && !/DW_AT_byte_size/ { s = 0; next }
+		c == 1 && /DW_TAG_structure_type/ { c = 2; next }
+		c == 1 && /DW_AT_name.* force[[:space:]]*$/ {d = 1; next}
 
 		# Now that we know the size, stop parsing for it
 		a == 1 {printf("export ALT_STRUCT_SIZE=%d\n", $4); a = 2}
@@ -406,6 +409,7 @@ find_special_section_data() {
 		o == 1 {printf("export ORC_STRUCT_SIZE=%d\n", $4); o = 2}
 		p == 1 {printf("export PARA_STRUCT_SIZE=%d\n", $4); p = 2}
 		s == 1 {printf("export STATIC_CALL_STRUCT_SIZE=%d\n", $4); s = 2}
+		d == 1 {printf("export KLP_SUPPORT_FORCE=y\n"); d = 2}
 
 		# Bail out once we have everything
 		(!check_a || a == 2) &&
@@ -416,7 +420,8 @@ find_special_section_data() {
 		(!check_j || j == 2) &&
 		(!check_o || o == 2) &&
 		(!check_p || p == 2) &&
-		(!check_s || s == 2) {exit}')"
+		(!check_s || s == 2) &&
+		c == 2 {exit}')"
 
 	[[ -n "$SPECIAL_VARS" ]] && eval "$SPECIAL_VARS"
 
@@ -1435,6 +1440,14 @@ if [[ -n "$DISABLE_AFTER_LOAD" ]];then
 	export KCPPFLAGS="-DDISABLE_AFTER_LOAD $KCPPFLAGS"
 fi
 
+if [[ -n "$NO_STACK_CHECK" ]];then
+	export KCPPFLAGS="-D__ALL_FORCE__ $KCPPFLAGS"
+fi
+
+if [[ -n "$KLP_SUPPORT_FORCE" ]];then
+	export KCPPFLAGS="-D__KLP_SUPPORT_FORCE__ $KCPPFLAGS"
+fi
+
 save_env
 
 echo "Building patch module: $MODNAME.ko"
-- 
2.33.0