ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not PREEMPT alone

[pandora-kernel.git] / arch / arm / vfp / vfphw.S

diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
index 2d30c7f..6ff903e 100644 (file)
--- a/arch/arm/vfp/vfphw.S
+++ b/arch/arm/vfp/vfphw.S
@@ -61,13 +61,13 @@
 
 @ VFP hardware support entry point.
 @
-@  r0  = faulted instruction
-@  r2  = faulted PC+4
-@  r9  = successful return
+@  r0  = instruction opcode (32-bit ARM or two 16-bit Thumb)
+@  r2  = PC value to resume execution after successful emulation
+@  r9  = normal "successful" return address
 @  r10 = vfp_state union
 @  r11 = CPU number
-@  lr  = failure return
-
+@  lr  = unrecognised instruction return address
+@  IRQs enabled.
 ENTRY(vfp_support_entry)
        DBGSTR3 "instr %08x pc %08x state %p", r0, r2, r10
 
@@ -161,10 +161,13 @@ vfp_hw_state_valid:
                                        @ exception before retrying branch
                                        @ out before setting an FPEXC that
                                        @ stops us reading stuff
-       VFPFMXR FPEXC, r1               @ restore FPEXC last
-       sub     r2, r2, #4
-       str     r2, [sp, #S_PC]         @ retry the instruction
-#ifdef CONFIG_PREEMPT
+       VFPFMXR FPEXC, r1               @ Restore FPEXC last
+       sub     r2, r2, #4              @ Retry current instruction - if Thumb
+       str     r2, [sp, #S_PC]         @ mode it's two 16-bit instructions,
+                                       @ else it's one 32-bit instruction, so
+                                       @ always subtract 4 from the following
+                                       @ instruction address.
+#ifdef CONFIG_PREEMPT_COUNT
        get_thread_info r10
        ldr     r4, [r10, #TI_PREEMPT]  @ get preempt count
        sub     r11, r4, #1             @ decrement it
@@ -188,7 +191,7 @@ look_for_VFP_exceptions:
        @ not recognised by VFP
 
        DBGSTR  "not VFP"
-#ifdef CONFIG_PREEMPT
+#ifdef CONFIG_PREEMPT_COUNT
        get_thread_info r10
        ldr     r4, [r10, #TI_PREEMPT]  @ get preempt count
        sub     r11, r4, #1             @ decrement it