Arm64: VDSO support for signal

The vdso is enabled, so we can use the sigreturn trampolines
the vdso provides in arch module.

Signed-off-by: Bin Lu <bin.lu@arm.com>

3 files changed, 20 insertions, 18 deletions

diff --git a/vdso/syscalls.h b/vdso/syscalls.h
index b6d15a7d3..f630ae563 100644
--- a/vdso/syscalls.h
+++ b/vdso/syscalls.h
@@ -26,6 +26,9 @@
 #include <stddef.h>
 #include <sys/types.h>
 
+#define __stringify_1(x...)     #x
+#define __stringify(x...)       __stringify_1(x)
+
 namespace vdso {
 
 #if __x86_64__
@@ -51,20 +54,13 @@ static inline int sys_getcpu(unsigned* cpu, unsigned* node,
   return num;
 }
 
-#elif __aarch64__
-
-static inline int sys_rt_sigreturn(void) {
-  int num = __NR_rt_sigreturn;
-
-  asm volatile(
-      "mov x8, %0\n"
-      "svc #0    \n"
-      : "+r"(num)
-      :
-      :);
-  return num;
+static inline void sys_rt_sigreturn(void) {
+  asm volatile("movl $" __stringify(__NR_rt_sigreturn)", %eax \n"
+               "syscall \n");
 }
 
+#elif __aarch64__
+
 static inline int sys_clock_gettime(clockid_t _clkid, struct timespec* _ts) {
   register struct timespec* ts asm("x1") = _ts;
   register clockid_t clkid asm("x0") = _clkid;
@@ -91,6 +87,11 @@ static inline int sys_clock_getres(clockid_t _clkid, struct timespec* _ts) {
   return ret;
 }
 
+static inline void sys_rt_sigreturn(void) {
+  asm volatile("mov x8, #" __stringify(__NR_rt_sigreturn)" \n"
+               "svc #0 \n");
+}
+
 #else
 #error "unsupported architecture"
 #endif
diff --git a/vdso/vdso.cc b/vdso/vdso.cc
index 8bb80a7a4..62f59766d 100644
--- a/vdso/vdso.cc
+++ b/vdso/vdso.cc
@@ -69,6 +69,12 @@ int __common_gettimeofday(struct timeval* tv, struct timezone* tz) {
 }
 }  // namespace
 
+// __kernel_rt_sigreturn() implements rt_sigreturn()
+extern "C" void __kernel_rt_sigreturn(unsigned long unused) {
+  // No optimizations yet, just make the real system call.
+  sys_rt_sigreturn();
+}
+
 #if __x86_64__
 
 // __vdso_clock_gettime() implements clock_gettime()
@@ -139,12 +145,6 @@ extern "C" int __kernel_clock_getres(clockid_t clock, struct timespec* res) {
   return ret;
 }
 
-// __kernel_rt_sigreturn() implements gettimeofday()
-extern "C" int __kernel_rt_sigreturn(unsigned long unused) {
-  // No optimizations yet, just make the real system call.
-  return sys_rt_sigreturn();
-}
-
 #else
 #error "unsupported architecture"
 #endif
diff --git a/vdso/vdso_amd64.lds b/vdso/vdso_amd64.lds
index e2615ae9e..d114290da 100644
--- a/vdso/vdso_amd64.lds
+++ b/vdso/vdso_amd64.lds
@@ -95,6 +95,7 @@ VERSION {
     __vdso_getcpu;
     time;
     __vdso_time;
+    __kernel_rt_sigreturn;
 
   local: *;
   };