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 <edgar.iglesias@gmail.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/cris/target_signal.h |  2 ++
 linux-user/cris/signal.c        | 29 +++++++++++++++++++++--------
 2 files changed, 23 insertions(+), 8 deletions(-)

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..9dad50f31f 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, 6, 0);
+    assert(tramp != NULL);
+
+    default_sigreturn = sigtramp_page;
+    setup_sigreturn(tramp);
+
+    unlock_user(tramp, sigtramp_page, 6);
+}
-- 
2.25.1

On 6/18/21 9:29 PM, 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 <edgar.iglesias@gmail.com>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  linux-user/cris/target_signal.h |  2 ++
>  linux-user/cris/signal.c        | 29 +++++++++++++++++++++--------
>  2 files changed, 23 insertions(+), 8 deletions(-)

Nitpicking, 6 -> 3 * 2? :)

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

On 6/19/21 2:33 AM, Philippe Mathieu-Daudé wrote:
> On 6/18/21 9:29 PM, 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 <edgar.iglesias@gmail.com>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>   linux-user/cris/target_signal.h |  2 ++
>>   linux-user/cris/signal.c        | 29 +++++++++++++++++++++--------
>>   2 files changed, 23 insertions(+), 8 deletions(-)
> 
> Nitpicking, 6 -> 3 * 2? :)

Elsewhere I have used <bytes-per-tramp> * 2 if we have two trampolines, not 
<bytes-per-insn> * <n-insns>.

r~

> 
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> 

On 6/19/21 2:55 PM, Richard Henderson wrote:
> On 6/19/21 2:33 AM, Philippe Mathieu-Daudé wrote:
>> On 6/18/21 9:29 PM, 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 <edgar.iglesias@gmail.com>
>>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>>> ---
>>>   linux-user/cris/target_signal.h |  2 ++
>>>   linux-user/cris/signal.c        | 29 +++++++++++++++++++++--------
>>>   2 files changed, 23 insertions(+), 8 deletions(-)
>>
>> Nitpicking, 6 -> 3 * 2? :)
> 
> Elsewhere I have used <bytes-per-tramp> * 2 if we have two trampolines,
> not <bytes-per-insn> * <n-insns>.

Oh, OK :)

>>
>> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>