1 files changed, 55 insertions, 12 deletions

diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index f05a35a59694..2d23ad985180 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -48,6 +48,8 @@ work_pending:
         beq     no_work_pending
         mov     r0, sp                          @ 'regs'
         mov     r2, why                         @ 'syscall'
+        tst     r1, #_TIF_SIGPENDING            @ delivering a signal?
+        movne   why, #0                         @ prevent further restarts
         bl      do_notify_resume
         b       ret_slow_syscall                @ Check work again
 
@@ -127,30 +129,58 @@ ENDPROC(ret_from_fork)
  * clobber the ip register.  This is OK because the ARM calling convention
  * allows it to be clobbered in subroutines and doesn't use it to hold
  * parameters.)
+ *
+ * When using dynamic ftrace, we patch out the mcount call by a "mov r0, r0"
+ * for the mcount case, and a "pop {lr}" for the __gnu_mcount_nc case (see
+ * arch/arm/kernel/ftrace.c).
  */
+
+#ifndef CONFIG_OLD_MCOUNT
+#if (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 4))
+#error Ftrace requires CONFIG_FRAME_POINTER=y with GCC older than 4.4.0.
+#endif
+#endif
+
 #ifdef CONFIG_DYNAMIC_FTRACE
-ENTRY(mcount)
+ENTRY(__gnu_mcount_nc)
+        mov     ip, lr
+        ldmia   sp!, {lr}
+        mov     pc, ip
+ENDPROC(__gnu_mcount_nc)
+
+ENTRY(ftrace_caller)
         stmdb   sp!, {r0-r3, lr}
         mov     r0, lr
         sub     r0, r0, #MCOUNT_INSN_SIZE
+        ldr     r1, [sp, #20]
 
-        .globl mcount_call
-mcount_call:
+        .global ftrace_call
+ftrace_call:
         bl      ftrace_stub
-        ldr     lr, [fp, #-4]                   @ restore lr
-        ldmia   sp!, {r0-r3, pc}
+        ldmia   sp!, {r0-r3, ip, lr}
+        mov     pc, ip
+ENDPROC(ftrace_caller)
 
-ENTRY(ftrace_caller)
+#ifdef CONFIG_OLD_MCOUNT
+ENTRY(mcount)
+        stmdb   sp!, {lr}
+        ldr     lr, [fp, #-4]
+        ldmia   sp!, {pc}
+ENDPROC(mcount)
+
+ENTRY(ftrace_caller_old)
         stmdb   sp!, {r0-r3, lr}
         ldr     r1, [fp, #-4]
         mov     r0, lr
         sub     r0, r0, #MCOUNT_INSN_SIZE
 
-        .globl ftrace_call
-ftrace_call:
+        .globl ftrace_call_old
+ftrace_call_old:
         bl      ftrace_stub
         ldr     lr, [fp, #-4]                   @ restore lr
         ldmia   sp!, {r0-r3, pc}
+ENDPROC(ftrace_caller_old)
+#endif
 
 #else
 
@@ -158,7 +188,7 @@ ENTRY(__gnu_mcount_nc)
         stmdb   sp!, {r0-r3, lr}
         ldr     r0, =ftrace_trace_function
         ldr     r2, [r0]
-        adr     r0, ftrace_stub
+        adr     r0, .Lftrace_stub
         cmp     r0, r2
         bne     gnu_trace
         ldmia   sp!, {r0-r3, ip, lr}
@@ -168,11 +198,19 @@ gnu_trace:
         ldr     r1, [sp, #20]                   @ lr of instrumented routine
         mov     r0, lr
         sub     r0, r0, #MCOUNT_INSN_SIZE
-        mov     lr, pc
+        adr     lr, BSYM(1f)
         mov     pc, r2
+1:
         ldmia   sp!, {r0-r3, ip, lr}
         mov     pc, ip
+ENDPROC(__gnu_mcount_nc)
 
+#ifdef CONFIG_OLD_MCOUNT
+/*
+ * This is under an ifdef in order to force link-time errors for people trying
+ * to build with !FRAME_POINTER with a GCC which doesn't use the new-style
+ * mcount.
+ */
 ENTRY(mcount)
         stmdb   sp!, {r0-r3, lr}
         ldr     r0, =ftrace_trace_function
@@ -191,12 +229,15 @@ trace:
         mov     pc, r2
         ldr     lr, [fp, #-4]                   @ restore lr
         ldmia   sp!, {r0-r3, pc}
+ENDPROC(mcount)
+#endif
 
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
-        .globl ftrace_stub
-ftrace_stub:
+ENTRY(ftrace_stub)
+.Lftrace_stub:
         mov     pc, lr
+ENDPROC(ftrace_stub)
 
 #endif /* CONFIG_FUNCTION_TRACER */
 
@@ -418,11 +459,13 @@ ENDPROC(sys_clone_wrapper)
 
 sys_sigreturn_wrapper:
                 add     r0, sp, #S_OFF
+                mov     why, #0         @ prevent syscall restart handling
                 b       sys_sigreturn
 ENDPROC(sys_sigreturn_wrapper)
 
 sys_rt_sigreturn_wrapper:
                 add     r0, sp, #S_OFF
+                mov     why, #0         @ prevent syscall restart handling
                 b       sys_rt_sigreturn
 ENDPROC(sys_rt_sigreturn_wrapper)