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-rw-r--r--arch/arm/vfp/vfphw.S19
1 files changed, 11 insertions, 8 deletions
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
index 2d30c7f..3a0efaa 100644
--- 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
@@ -161,9 +161,12 @@ 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
+ 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
get_thread_info r10
ldr r4, [r10, #TI_PREEMPT] @ get preempt count