[Qemu-devel] [PATCH] linux-user,sh4: fix signal retcode address

[Laurent Vivier <laurent@vivier.eu>]

To return from a signal, setup_frame() puts an instruction to
be executed in the stack. This sequence calls the syscall sigreturn().

The address of the instruction must be set in the PR register
to be executed.

This patch fixes this: the current code sets the register to the address
of the instruction in the host address space (which can be 64bit whereas
PR is only 32bit), but the virtual CPU can't access this address space,
so we put in PR the address of the instruction in the guest address space.

This patch also removes an useless variable (ret) in the modified functions.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 linux-user/signal.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/linux-user/signal.c b/linux-user/signal.c
index 55e5405..5e8f6d8 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -3215,7 +3215,6 @@ static void setup_frame(int sig, struct target_sigaction *ka,
     struct target_sigframe *frame;
     abi_ulong frame_addr;
     int i;
-    int err = 0;
 
     frame_addr = get_sigframe(ka, regs->gregs[15], sizeof(*frame));
     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0))
@@ -3233,15 +3232,14 @@ static void setup_frame(int sig, struct target_sigaction *ka,
         regs->pr = (unsigned long) ka->sa_restorer;
     } else {
         /* Generate return code (system call to sigreturn) */
+        abi_ulong retcode_addr = frame_addr +
+                                 offsetof(struct target_sigframe, retcode);
         __put_user(MOVW(2), &frame->retcode[0]);
         __put_user(TRAP_NOARG, &frame->retcode[1]);
         __put_user((TARGET_NR_sigreturn), &frame->retcode[2]);
-        regs->pr = (unsigned long) frame->retcode;
+        regs->pr = (unsigned long) retcode_addr;
     }
 
-    if (err)
-        goto give_sigsegv;
-
     /* Set up registers for signal handler */
     regs->gregs[15] = frame_addr;
     regs->gregs[4] = sig; /* Arg for signal handler */
@@ -3264,7 +3262,6 @@ static void setup_rt_frame(int sig, struct target_sigaction *ka,
     struct target_rt_sigframe *frame;
     abi_ulong frame_addr;
     int i;
-    int err = 0;
 
     frame_addr = get_sigframe(ka, regs->gregs[15], sizeof(*frame));
     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0))
@@ -3293,15 +3290,14 @@ static void setup_rt_frame(int sig, struct target_sigaction *ka,
         regs->pr = (unsigned long) ka->sa_restorer;
     } else {
         /* Generate return code (system call to sigreturn) */
+        abi_ulong retcode_addr = frame_addr +
+                                 offsetof(struct target_rt_sigframe, retcode);
         __put_user(MOVW(2), &frame->retcode[0]);
         __put_user(TRAP_NOARG, &frame->retcode[1]);
         __put_user((TARGET_NR_rt_sigreturn), &frame->retcode[2]);
-        regs->pr = (unsigned long) frame->retcode;
+        regs->pr = (unsigned long) retcode_addr;
     }
 
-    if (err)
-        goto give_sigsegv;
-
     /* Set up registers for signal handler */
     regs->gregs[15] = frame_addr;
     regs->gregs[4] = sig; /* Arg for signal handler */
-- 
2.4.3