1 files changed, 21 insertions, 3 deletions

diff --git a/arch/tile/kernel/intvec_32.S b/arch/tile/kernel/intvec_32.S
index f5821626247..5eed4a02bf6 100644
--- a/arch/tile/kernel/intvec_32.S
+++ b/arch/tile/kernel/intvec_32.S
@@ -1342,8 +1342,8 @@ handle_syscall:
         lw      r20, r20
 
         /* Jump to syscall handler. */
-        jalr    r20; .Lhandle_syscall_link:
-        FEEDBACK_REENTER(handle_syscall)
+        jalr    r20
+.Lhandle_syscall_link: /* value of "lr" after "jalr r20" above */
 
         /*
          * Write our r0 onto the stack so it gets restored instead
@@ -1352,6 +1352,9 @@ handle_syscall:
         PTREGS_PTR(r29, PTREGS_OFFSET_REG(0))
         sw      r29, r0
 
+.Lsyscall_sigreturn_skip:
+        FEEDBACK_REENTER(handle_syscall)
+
         /* Do syscall trace again, if requested. */
         lw      r30, r31
         andi    r30, r30, _TIF_SYSCALL_TRACE
@@ -1536,9 +1539,24 @@ STD_ENTRY_LOCAL(bad_intr)
         };                                              \
         STD_ENDPROC(_##x)
 
+/*
+ * Special-case sigreturn to not write r0 to the stack on return.
+ * This is technically more efficient, but it also avoids difficulties
+ * in the 64-bit OS when handling 32-bit compat code, since we must not
+ * sign-extend r0 for the sigreturn return-value case.
+ */
+#define PTREGS_SYSCALL_SIGRETURN(x, reg)                \
+        STD_ENTRY(_##x);                                \
+        addli   lr, lr, .Lsyscall_sigreturn_skip - .Lhandle_syscall_link; \
+        {                                               \
+         PTREGS_PTR(reg, PTREGS_OFFSET_BASE);           \
+         j      x                                       \
+        };                                              \
+        STD_ENDPROC(_##x)
+
 PTREGS_SYSCALL(sys_execve, r3)
 PTREGS_SYSCALL(sys_sigaltstack, r2)
-PTREGS_SYSCALL(sys_rt_sigreturn, r0)
+PTREGS_SYSCALL_SIGRETURN(sys_rt_sigreturn, r0)
 PTREGS_SYSCALL(sys_cmpxchg_badaddr, r1)
 
 /* Save additional callee-saves to pt_regs, put address in r4 and jump. */