Merge remote-tracking branch 'remotes/vivier/tags/linux-user-for-6.2-pull-request' into staging

Pull request linux-user 20211004

Move signal trampolines to new page

# gpg: Signature made Mon 04 Oct 2021 12:43:53 AM PDT
# gpg:                using RSA key CD2F75DDC8E3A4DC2E4F5173F30C38BD3F2FBE3C
# gpg:                issuer "laurent@vivier.eu"
# gpg: Good signature from "Laurent Vivier <lvivier@redhat.com>" [full]
# gpg:                 aka "Laurent Vivier <laurent@vivier.eu>" [full]
# gpg:                 aka "Laurent Vivier (Red Hat) <lvivier@redhat.com>" [full]

* remotes/vivier/tags/linux-user-for-6.2-pull-request: (26 commits)
  tests/tcg/multiarch: Re-enable signals test for most guests
  linux-user: Remove default for TARGET_ARCH_HAS_SIGTRAMP_PAGE
  linux-user/xtensa: Implement setup_sigtramp
  linux-user/sparc: Implement setup_sigtramp
  linux-user/sh4: Implement setup_sigtramp
  linux-user/s390x: Implement setup_sigtramp
  linux-user/riscv: Implement setup_sigtramp
  linux-user/ppc: Implement setup_sigtramp
  linux-user/ppc: Simplify encode_trampoline
  linux-user/openrisc: Implement setup_sigtramp
  linux-user/nios2: Document non-use of setup_sigtramp
  linux-user/mips: Implement setup_sigtramp
  linux-user/mips: Tidy install_sigtramp
  linux-user/microblaze: Implement setup_sigtramp
  linux-user/m68k: Implement setup_sigtramp
  linux-user/x86_64: Raise SIGSEGV if SA_RESTORER not set
  linux-user/i386: Implement setup_sigtramp
  linux-user/hppa: Document non-use of setup_sigtramp
  linux-user/hexagon: Implement setup_sigtramp
  linux-user/cris: Implement setup_sigtramp
  ...

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 42 insertions, 23 deletions

diff --git a/linux-user/i386/signal.c b/linux-user/i386/signal.c
index 3b4b55fc0a..433efa3d69 100644
--- a/linux-user/i386/signal.c
+++ b/linux-user/i386/signal.c
@@ -310,6 +310,22 @@ get_sigframe(struct target_sigaction *ka, CPUX86State *env, size_t frame_size)
 }
 
 #ifndef TARGET_X86_64
+static void install_sigtramp(void *tramp)
+{
+    /* This is popl %eax ; movl $syscall,%eax ; int $0x80 */
+    __put_user(0xb858, (uint16_t *)(tramp + 0));
+    __put_user(TARGET_NR_sigreturn, (int32_t *)(tramp + 2));
+    __put_user(0x80cd, (uint16_t *)(tramp + 6));
+}
+
+static void install_rt_sigtramp(void *tramp)
+{
+    /* This is movl $syscall,%eax ; int $0x80 */
+    __put_user(0xb8, (uint8_t *)(tramp + 0));
+    __put_user(TARGET_NR_rt_sigreturn, (int32_t *)(tramp + 1));
+    __put_user(0x80cd, (uint16_t *)(tramp + 5));
+}
+
 /* compare linux/arch/i386/kernel/signal.c:setup_frame() */
 void setup_frame(int sig, struct target_sigaction *ka,
                  target_sigset_t *set, CPUX86State *env)
@@ -338,16 +354,9 @@ void setup_frame(int sig, struct target_sigaction *ka,
     if (ka->sa_flags & TARGET_SA_RESTORER) {
         __put_user(ka->sa_restorer, &frame->pretcode);
     } else {
-        uint16_t val16;
-        abi_ulong retcode_addr;
-        retcode_addr = frame_addr + offsetof(struct sigframe, retcode);
-        __put_user(retcode_addr, &frame->pretcode);
-        /* This is popl %eax ; movl $,%eax ; int $0x80 */
-        val16 = 0xb858;
-        __put_user(val16, (uint16_t *)(frame->retcode+0));
-        __put_user(TARGET_NR_sigreturn, (int *)(frame->retcode+2));
-        val16 = 0x80cd;
-        __put_user(val16, (uint16_t *)(frame->retcode+6));
+        /* This is no longer used, but is retained for ABI compatibility. */
+        install_sigtramp(frame->retcode);
+        __put_user(default_sigreturn, &frame->pretcode);
     }
 
     /* Set up registers for signal handler */
@@ -412,24 +421,18 @@ 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 {
-        uint16_t val16;
-        addr = frame_addr + offsetof(struct rt_sigframe, retcode);
-        __put_user(addr, &frame->pretcode);
-        /* This is movl $,%eax ; int $0x80 */
-        __put_user(0xb8, (char *)(frame->retcode+0));
-        __put_user(TARGET_NR_rt_sigreturn, (int *)(frame->retcode+1));
-        val16 = 0x80cd;
-        __put_user(val16, (uint16_t *)(frame->retcode+5));
-    }
+#ifdef TARGET_X86_64
+        /* For x86_64, SA_RESTORER is required ABI.  */
+        goto give_sigsegv;
 #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);
+        /* This is no longer used, but is retained for ABI compatibility. */
+        install_rt_sigtramp(frame->retcode);
+        __put_user(default_rt_sigreturn, &frame->pretcode);
 #endif
+    }
 
     /* Set up registers for signal handler */
     env->regs[R_ESP] = frame_addr;
@@ -592,3 +595,19 @@ badframe:
     force_sig(TARGET_SIGSEGV);
     return -TARGET_QEMU_ESIGRETURN;
 }
+
+#ifndef TARGET_X86_64
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+    uint16_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 2 * 8, 0);
+    assert(tramp != NULL);
+
+    default_sigreturn = sigtramp_page;
+    install_sigtramp(tramp);
+
+    default_rt_sigreturn = sigtramp_page + 8;
+    install_rt_sigtramp(tramp + 8);
+
+    unlock_user(tramp, sigtramp_page, 2 * 8);
+}
+#endif