[Qemu-devel] [PULL 04/52] linux-user: Split PPC Trampoline Encoding from Register Save

[Alexander Graf]

From: Tom Musta <address@hidden>

Split the encoding of the PowerPC sigreturn trampoline from the saving of
register state onto the signal handler stack.  This will make it easier
in subsequent patches to deal with variations in the stack frame layouts between
32 and 64 bit PowerPC.

Signed-off-by: Tom Musta <address@hidden>
Signed-off-by: Alexander Graf <address@hidden>
---
 linux-user/signal.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/linux-user/signal.c b/linux-user/signal.c
index 2952956..7365d5d 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -4491,8 +4491,7 @@ static target_ulong get_sigframe(struct target_sigaction 
*ka,
     return newsp;
 }
 
-static void save_user_regs(CPUPPCState *env, struct target_mcontext *frame,
-                          int sigret)
+static void save_user_regs(CPUPPCState *env, struct target_mcontext *frame)
 {
     target_ulong msr = env->msr;
     int i;
@@ -4559,11 +4558,14 @@ static void save_user_regs(CPUPPCState *env, struct 
target_mcontext *frame,
 
     /* Store MSR.  */
     __put_user(msr, &frame->mc_gregs[TARGET_PT_MSR]);
+}
 
+static void encode_trampoline(int sigret, uint32_t *tramp)
+{
     /* Set up the sigreturn trampoline: li r0,sigret; sc.  */
     if (sigret) {
-        __put_user(0x38000000UL | sigret, &frame->tramp[0]);
-        __put_user(0x44000002UL, &frame->tramp[1]);
+        __put_user(0x38000000 | sigret, &tramp[0]);
+        __put_user(0x44000002, &tramp[1]);
     }
 }
 
@@ -4674,7 +4676,10 @@ static void setup_frame(int sig, struct target_sigaction 
*ka,
     __put_user(sig, &sc->signal);
 
     /* Save user regs.  */
-    save_user_regs(env, &frame->mctx, TARGET_NR_sigreturn);
+    save_user_regs(env, &frame->mctx);
+
+    /* Construct the trampoline code on the stack. */
+    encode_trampoline(TARGET_NR_sigreturn, (uint32_t *)&frame->mctx.tramp);
 
     /* The kernel checks for the presence of a VDSO here.  We don't
        emulate a vdso, so use a sigreturn system call.  */
@@ -4740,7 +4745,8 @@ static void setup_rt_frame(int sig, struct 
target_sigaction *ka,
     }
 
     frame = &rt_sf->uc.tuc_mcontext;
-    save_user_regs(env, frame, TARGET_NR_rt_sigreturn);
+    save_user_regs(env, frame);
+    encode_trampoline(TARGET_NR_rt_sigreturn, (uint32_t *)&frame->tramp);
 
     /* The kernel checks for the presence of a VDSO here.  We don't
        emulate a vdso, so use a sigreturn system call.  */
-- 
1.8.1.4