[06/21] linux-user/cris: Implement setup_sigtramp

Commit Message

Richard Henderson June 16, 2021, 1:11 a.m. UTC

Split out setup_sigreturn so that we can continue to
initialize the words on the stack, as documented.
However, use the off-stack trampoline.

Cc: Edgar E. Iglesias <[e-mail]>
Signed-off-by: Richard Henderson <[e-mail]>
---
 linux-user/cris/target_signal.h |  2 ++
 linux-user/cris/signal.c        | 29 +++++++++++++++++++++--------
 2 files changed, 23 insertions(+), 8 deletions(-)

Comments

Philippe Mathieu-Daudé June 16, 2021, 4:37 p.m. UTC | #1

On 6/16/21 3:11 AM, Richard Henderson wrote:
> Split out setup_sigreturn so that we can continue to
> initialize the words on the stack, as documented.
> However, use the off-stack trampoline.
> 
> Cc: Edgar E. Iglesias <[e-mail]>
> Signed-off-by: Richard Henderson <[e-mail]>
> ---
>  linux-user/cris/target_signal.h |  2 ++
>  linux-user/cris/signal.c        | 29 +++++++++++++++++++++--------
>  2 files changed, 23 insertions(+), 8 deletions(-)

> +void setup_sigtramp(abi_ulong sigtramp_page)
> +{
> +    uint16_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 4 * 2, 0);

3 * 2?

> +    assert(tramp != NULL);
> +
> +    default_sigreturn = sigtramp_page;
> +    setup_sigreturn(tramp);
> +
> +    unlock_user(tramp, sigtramp_page, 4 * 2);

Ditto.

> +}
>

Patch

diff --git a/linux-user/cris/target_signal.h b/linux-user/cris/target_signal.h
index 495a142896..83a5155507 100644
--- a/linux-user/cris/target_signal.h
+++ b/linux-user/cris/target_signal.h
@@ -22,4 +22,6 @@  typedef struct target_sigaltstack {
 #include "../generic/signal.h"
 
 #define TARGET_ARCH_HAS_SETUP_FRAME
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
+
 #endif /* CRIS_TARGET_SIGNAL_H */
diff --git a/linux-user/cris/signal.c b/linux-user/cris/signal.c
index 1e02194377..51d1ee877f 100644
--- a/linux-user/cris/signal.c
+++ b/linux-user/cris/signal.c
@@ -96,6 +96,14 @@  static abi_ulong get_sigframe(CPUCRISState *env, int framesize)
     return sp - framesize;
 }
 
+static void setup_sigreturn(uint16_t *retcode)
+{
+    /* This is movu.w __NR_sigreturn, r9; break 13; */
+    __put_user(0x9c5f, retcode + 0);
+    __put_user(TARGET_NR_sigreturn, retcode + 1);
+    __put_user(0xe93d, retcode + 2);
+}
+
 void setup_frame(int sig, struct target_sigaction *ka,
                  target_sigset_t *set, CPUCRISState *env)
 {
@@ -111,14 +119,8 @@  void setup_frame(int sig, struct target_sigaction *ka,
     /*
      * The CRIS signal return trampoline. A real linux/CRIS kernel doesn't
      * use this trampoline anymore but it sets it up for GDB.
-     * In QEMU, using the trampoline simplifies things a bit so we use it.
-     *
-     * This is movu.w __NR_sigreturn, r9; break 13;
      */
-    __put_user(0x9c5f, frame->retcode+0);
-    __put_user(TARGET_NR_sigreturn,
-               frame->retcode + 1);
-    __put_user(0xe93d, frame->retcode + 2);
+    setup_sigreturn(frame->retcode);
 
     /* Save the mask.  */
     __put_user(set->sig[0], &frame->sc.oldmask);
@@ -134,7 +136,7 @@  void setup_frame(int sig, struct target_sigaction *ka,
     env->regs[10] = sig;
     env->pc = (unsigned long) ka->_sa_handler;
     /* Link SRP so the guest returns through the trampoline.  */
-    env->pregs[PR_SRP] = frame_addr + offsetof(typeof(*frame), retcode);
+    env->pregs[PR_SRP] = default_sigreturn;
 
     unlock_user_struct(frame, frame_addr, 1);
     return;
@@ -186,3 +188,14 @@  long do_rt_sigreturn(CPUCRISState *env)
     qemu_log_mask(LOG_UNIMP, "do_rt_sigreturn: not implemented\n");
     return -TARGET_ENOSYS;
 }
+
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+    uint16_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 4 * 2, 0);
+    assert(tramp != NULL);
+
+    default_sigreturn = sigtramp_page;
+    setup_sigreturn(tramp);
+
+    unlock_user(tramp, sigtramp_page, 4 * 2);
+}