x86/32: rectify compatible jump trampolines

Reworked this code a little and it becomes more readable.
Drop those macroses under CONFIG_X86_64 define and just use
boolean `compat_vdso' to check whether insert 64 or 32-bit jmp.
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/arch/aarch64/vdso-pie.c

@@ -13,8 +13,8 @@
 #define LOG_PREFIX "vdso: "
 
 int vdso_redirect_calls(unsigned long base_to, unsigned long base_from,
-			struct vdso_symtable *to,
-			struct vdso_symtable *from)
+			struct vdso_symtable *to, struct vdso_symtable *from,
+			bool __always_unused compat_vdso)
 {
 	unsigned int i;
 

criu/arch/ppc64/vdso-pie.c

@@ -125,10 +125,9 @@ static inline void put_trampoline_call(unsigned long at, unsigned long to,
     invalidate_caches(at);
 }
 
-int vdso_redirect_calls(unsigned long base_to,
-			unsigned long base_from,
-			struct vdso_symtable *to,
-			struct vdso_symtable *from)
+int vdso_redirect_calls(unsigned long base_to, unsigned long base_from,
+			struct vdso_symtable *to, struct vdso_symtable *from,
+			bool __always_unused compat_vdso)
 {
 	unsigned int i;
 	unsigned long trampoline;

criu/arch/x86/vdso-pie.c

@@ -13,53 +13,63 @@
 #endif
 #define LOG_PREFIX "vdso: "
 
-#ifdef CONFIG_X86_64
-typedef struct {
-	u16	movabs;
-	u64	imm64;
-	u16	jmp_rax;
-	u32	guards;
-} __packed jmp_t;
-#define IMMEDIATE(j)	(j.imm64)
+static void insert_trampoline32(uintptr_t from, uintptr_t to)
+{
+	struct {
+		u8	movl;
+		u32	imm32;
+		u16	jmp_eax;
+		u32	guards;
+	} __packed jmp = {
+		.movl		= 0xb8,
+		.imm32		= (uint32_t)to,
+		.jmp_eax	= 0xe0ff,
+		.guards		= 0xcccccccc,
+	};
 
-jmp_t jmp = {
-	.movabs		= 0xb848,
-	.jmp_rax	= 0xe0ff,
-	.guards		= 0xcccccccc,
-};
+	memcpy((void *)from, &jmp, sizeof(jmp));
+}
 
-#else /* CONFIG_X86_64 */
-typedef struct {
-	u8	movl;
-	u32	imm32;
-	u16	jmp_eax;
-	u32	guards;
-} __packed jmp_t;
-#define IMMEDIATE(j)	(j.imm32)
+static void insert_trampoline64(uintptr_t from, uintptr_t to)
+{
+	struct {
+		u16	movabs;
+		u64	imm64;
+		u16	jmp_rax;
+		u32	guards;
+	} __packed jmp = {
+		.movabs		= 0xb848,
+		.imm64		= to,
+		.jmp_rax	= 0xe0ff,
+		.guards		= 0xcccccccc,
+	};
 
-jmp_t jmp = {
-	.movl		= 0xb8,
-	.jmp_eax	= 0xe0ff,
-	.guards		= 0xcccccccc,
-};
-#endif /* CONFIG_X86_64 */
+	memcpy((void *)from, &jmp, sizeof(jmp));
+}
 
 int vdso_redirect_calls(unsigned long base_to, unsigned long base_from,
-			struct vdso_symtable *to,
-			struct vdso_symtable *from)
+			struct vdso_symtable *sto, struct vdso_symtable *sfrom,
+			bool compat_vdso)
 {
 	unsigned int i;
 
-	for (i = 0; i < ARRAY_SIZE(to->symbols); i++) {
-		if (vdso_symbol_empty(&from->symbols[i]))
+	for (i = 0; i < ARRAY_SIZE(sto->symbols); i++) {
+		uintptr_t from, to;
+
+		if (vdso_symbol_empty(&sfrom->symbols[i]))
 			continue;
 
 		pr_debug("jmp: %lx/%lx -> %lx/%lx (index %d)\n",
-			 base_from, from->symbols[i].offset,
-			 base_to, to->symbols[i].offset, i);
+			 base_from, sfrom->symbols[i].offset,
+			 base_to, sto->symbols[i].offset, i);
+
+		from = base_from + sfrom->symbols[i].offset;
+		to = base_to + sto->symbols[i].offset;
 
-		IMMEDIATE(jmp) = base_to + to->symbols[i].offset;
-		memcpy((void *)(base_from + from->symbols[i].offset), &jmp, sizeof(jmp));
+		if (!compat_vdso)
+			insert_trampoline64(from, to);
+		else
+			insert_trampoline32(from, to);
 	}
 
 	return 0;

criu/include/parasite-vdso.h

@@ -86,7 +86,8 @@ extern int vdso_proxify(struct vdso_symtable *sym_rt,
 			VmaEntry *vmas, size_t nr_vmas,
 			bool compat_vdso, bool force_trampolines);
 extern int vdso_redirect_calls(unsigned long base_to, unsigned long base_from,
-			struct vdso_symtable *to, struct vdso_symtable *from);
+			struct vdso_symtable *to, struct vdso_symtable *from,
+			bool compat_vdso);
 
 #else /* CONFIG_VDSO */
 #define vdso_do_park(sym_rt, park_at, park_size)		(0)

criu/pie/parasite-vdso.c

@@ -242,7 +242,7 @@ int vdso_proxify(struct vdso_symtable *sym_rt, unsigned long vdso_rt_parked_at,
 
 	if (vdso_redirect_calls(vdso_rt_parked_at,
 				vma_vdso->start,
-				sym_rt, &s)) {
+				sym_rt, &s, compat_vdso)) {
 		pr_err("Failed to proxify dumpee contents\n");
 		return -1;
 	}