[Qemu-devel] [PATCH 4/7] linux-user: Properly Dereference PPC64 ELFv1 Signal Handler Pointer

[Tom Musta <tommusta@gmail.com>]

Properly dereference 64-bit PPC ELF V1 ABIT function pointers to signal handlers.
On this platform, function pointers are pointers to structures and the first 64
bits of such a structure contains the function's entry point.  The second 64 bits
contains the TOC pointer, which must be placed into GPR 2.

Signed-off-by: Tom Musta <tommusta@gmail.com>
---
 linux-user/signal.c |   29 +++++++++++++++++++++++++++++
 1 files changed, 29 insertions(+), 0 deletions(-)

diff --git a/linux-user/signal.c b/linux-user/signal.c
index 83bfcd6..7bd9a43 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -4472,6 +4472,15 @@ struct target_rt_sigframe {
 
 #endif
 
+#if defined(TARGET_PPC64)
+
+struct target_func_ptr {
+    target_ulong entry;
+    target_ulong toc;
+};
+
+#endif
+
 /* We use the mc_pad field for the signal return trampoline.  */
 #define tramp mc_pad
 
@@ -4703,7 +4712,17 @@ static void setup_frame(int sig, struct target_sigaction *ka,
     env->gpr[1] = newsp;
     env->gpr[3] = signal;
     env->gpr[4] = frame_addr + offsetof(struct target_sigframe, sctx);
+
+#if defined(TARGET_PPC64)
+    /* PPC64 function pointers are pointers to OPD entries. */
+    struct target_func_ptr *handler =
+        (struct target_func_ptr *)g2h(ka->_sa_handler);
+    env->nip = tswapl(handler->entry);
+    env->gpr[2] = tswapl(handler->toc);
+#else
     env->nip = (target_ulong) ka->_sa_handler;
+#endif
+
     /* Signal handlers are entered in big-endian mode.  */
     env->msr &= ~MSR_LE;
 
@@ -4782,7 +4801,17 @@ static void setup_rt_frame(int sig, struct target_sigaction *ka,
     env->gpr[4] = (target_ulong) h2g(&rt_sf->info);
     env->gpr[5] = (target_ulong) h2g(&rt_sf->uc);
     env->gpr[6] = (target_ulong) h2g(rt_sf);
+
+#if defined(TARGET_PPC64)
+    /* PPC64 function pointers are pointers to OPD entries.  */
+    struct target_func_ptr *handler =
+        (struct target_func_ptr *)g2h(ka->_sa_handler);
+    env->nip = tswapl(handler->entry);
+    env->gpr[2] = tswapl(handler->toc);
+#else
     env->nip = (target_ulong) ka->_sa_handler;
+#endif
+
     /* Signal handlers are entered in big-endian mode.  */
     env->msr &= ~MSR_LE;
 
-- 
1.7.1