[CRIU] [PATCH 04/11] vdso/arm32: Add vdso trampoline support

[Dmitry Safonov]

Signed-off-by: Dmitry Safonov <dima at arista.com>
---
 criu/arch/arm/vdso-pie.c | 58 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 criu/arch/arm/vdso-pie.c

diff --git a/criu/arch/arm/vdso-pie.c b/criu/arch/arm/vdso-pie.c
new file mode 100644
index 000000000000..0ec8bd9a8c8e
--- /dev/null
+++ b/criu/arch/arm/vdso-pie.c
@@ -0,0 +1,58 @@
+#include <unistd.h>
+
+#include "asm/types.h"
+
+#include <compel/plugins/std/string.h>
+#include <compel/plugins/std/syscall.h>
+#include "parasite-vdso.h"
+#include "log.h"
+#include "common/bug.h"
+
+#ifdef LOG_PREFIX
+# undef LOG_PREFIX
+#endif
+#define LOG_PREFIX "vdso: "
+
+static void insert_trampoline(uintptr_t from, uintptr_t to)
+{
+	struct {
+		uint32_t	ldr_pc;
+		uint32_t	imm32;
+		uint32_t	guards;
+	} __packed jmp = {
+		.ldr_pc		= 0xe51ff004,		/* ldr	pc, [pc, #-4] */
+		.imm32		= to,
+		.guards		= 0xe1200070,		/* bkpt	0x0000 */
+	};
+	void *iflush_start	= (void *)from;
+	void *iflush_end	= iflush_start + sizeof(jmp);
+
+	memcpy((void *)from, &jmp, sizeof(jmp));
+
+	__builtin___clear_cache(iflush_start, iflush_end);
+}
+
+int vdso_redirect_calls(unsigned long base_to, unsigned long base_from,
+			struct vdso_symtable *sto, struct vdso_symtable *sfrom,
+			bool compat_vdso)
+{
+	unsigned int 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, 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;
+
+		insert_trampoline(from, to);
+	}
+
+	return 0;
+}
-- 
2.21.0