[v2,21/36] linux-user/x86_64: Raise SIGSEGV if SA_RESTORER not set

Commit Message

Richard Henderson July 6, 2021, 11:49 p.m. UTC

This has been a fixme for some time.  The effect of
returning -EFAULT from the kernel code is to raise SIGSEGV.

Signed-off-by: Richard Henderson <[e-mail]>
---
 linux-user/i386/signal.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

Patch

diff --git a/linux-user/i386/signal.c b/linux-user/i386/signal.c
index 8701774e37..9894e7c9ac 100644
--- a/linux-user/i386/signal.c
+++ b/linux-user/i386/signal.c
@@ -411,10 +411,13 @@  void setup_rt_frame(int sig, struct target_sigaction *ka,
 
     /* Set up to return from userspace.  If provided, use a stub
        already in userspace.  */
-#ifndef TARGET_X86_64
     if (ka->sa_flags & TARGET_SA_RESTORER) {
         __put_user(ka->sa_restorer, &frame->pretcode);
     } else {
+#ifdef TARGET_X86_64
+        /* For x86_64, SA_RESTORER is required ABI.  */
+        goto give_sigsegv;
+#else
         uint16_t val16;
         addr = frame_addr + offsetof(struct rt_sigframe, retcode);
         __put_user(addr, &frame->pretcode);
@@ -423,12 +426,8 @@  void setup_rt_frame(int sig, struct target_sigaction *ka,
         __put_user(TARGET_NR_rt_sigreturn, (int *)(frame->retcode+1));
         val16 = 0x80cd;
         __put_user(val16, (uint16_t *)(frame->retcode+5));
-    }
-#else
-    /* XXX: Would be slightly better to return -EFAULT here if test fails
-       assert(ka->sa_flags & TARGET_SA_RESTORER); */
-    __put_user(ka->sa_restorer, &frame->pretcode);
 #endif
+    }
 
     /* Set up registers for signal handler */
     env->regs[R_ESP] = frame_addr;