powerpc: ELF2 binaries signal handling

For the ELFv2 ABI, the hander is the entry point, not a function descriptor.
We also need to set up r12, and fortunately the fast_exception_return
exit path restores r12 for us so nothing else is required.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 16 insertions, 9 deletions

diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index b3c615764c9b..e66f67b8b9e6 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -701,12 +701,6 @@ badframe:
 int handle_rt_signal64(int signr, struct k_sigaction *ka, siginfo_t *info,
                 sigset_t *set, struct pt_regs *regs)
 {
-        /* Handler is *really* a pointer to the function descriptor for
-         * the signal routine.  The first entry in the function
-         * descriptor is the entry address of signal and the second
-         * entry is the TOC value we need to use.
-         */
-        func_descr_t __user *funct_desc_ptr;
         struct rt_sigframe __user *frame;
         unsigned long newsp = 0;
         long err = 0;
@@ -766,19 +760,32 @@ int handle_rt_signal64(int signr, struct k_sigaction *ka, siginfo_t *info,
                         goto badframe;
                 regs->link = (unsigned long) &frame->tramp[0];
         }
-        funct_desc_ptr = (func_descr_t __user *) ka->sa.sa_handler;
 
         /* Allocate a dummy caller frame for the signal handler. */
         newsp = ((unsigned long)frame) - __SIGNAL_FRAMESIZE;
         err |= put_user(regs->gpr[1], (unsigned long __user *)newsp);
 
         /* Set up "regs" so we "return" to the signal handler. */
-        err |= get_user(regs->nip, &funct_desc_ptr->entry);
+        if (is_elf2_task()) {
+                regs->nip = (unsigned long) ka->sa.sa_handler;
+                regs->gpr[12] = regs->nip;
+        } else {
+                /* Handler is *really* a pointer to the function descriptor for
+                 * the signal routine.  The first entry in the function
+                 * descriptor is the entry address of signal and the second
+                 * entry is the TOC value we need to use.
+                 */
+                func_descr_t __user *funct_desc_ptr =
+                        (func_descr_t __user *) ka->sa.sa_handler;
+
+                err |= get_user(regs->nip, &funct_desc_ptr->entry);
+                err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
+        }
+
         /* enter the signal handler in native-endian mode */
         regs->msr &= ~MSR_LE;
         regs->msr |= (MSR_KERNEL & MSR_LE);
         regs->gpr[1] = newsp;
-        err |= get_user(regs->gpr[2], &funct_desc_ptr->toc);
         regs->gpr[3] = signr;
         regs->result = 0;
         if (ka->sa.sa_flags & SA_SIGINFO) {