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authorCatalin Marinas <catalin.marinas@arm.com>2007-01-24 18:47:08 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2007-01-25 16:35:29 +0000
commitc6428464894889e110418928e6b37dc2eb4cee56 (patch)
tree292410b297ef2332715aabd7a87ef9fe0c03de4a /arch/arm/vfp/vfphw.S
parent412489af76b5c0e4029d4406d93554c22a88fc73 (diff)
[ARM] 4111/1: Allow VFP to work with thread migration on SMP
The current lazy saving of the VFP registers is no longer possible with thread migration on SMP. This patch implements a per-CPU vfp-state pointer and the saving of the VFP registers at every context switch. The registers restoring is still performed in a lazy way. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/vfp/vfphw.S')
-rw-r--r--arch/arm/vfp/vfphw.S26
1 files changed, 24 insertions, 2 deletions
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
index e51e6679c402..d4b7b229631d 100644
--- a/arch/arm/vfp/vfphw.S
+++ b/arch/arm/vfp/vfphw.S
@@ -65,6 +65,7 @@
@ r2 = faulted PC+4
@ r9 = successful return
@ r10 = vfp_state union
+@ r11 = CPU number
@ lr = failure return
.globl vfp_support_entry
@@ -79,7 +80,7 @@ vfp_support_entry:
DBGSTR1 "enable %x", r10
ldr r3, last_VFP_context_address
orr r1, r1, #FPEXC_ENABLE @ user FPEXC has the enable bit set
- ldr r4, [r3] @ last_VFP_context pointer
+ ldr r4, [r3, r11, lsl #2] @ last_VFP_context pointer
bic r5, r1, #FPEXC_EXCEPTION @ make sure exceptions are disabled
cmp r4, r10
beq check_for_exception @ we are returning to the same
@@ -91,7 +92,9 @@ vfp_support_entry:
@ exceptions, so we can get at the
@ rest of it
+#ifndef CONFIG_SMP
@ Save out the current registers to the old thread state
+ @ No need for SMP since this is not done lazily
DBGSTR1 "save old state %p", r4
cmp r4, #0
@@ -105,10 +108,11 @@ vfp_support_entry:
stmia r4, {r1, r5, r6, r8} @ save FPEXC, FPSCR, FPINST, FPINST2
@ and point r4 at the word at the
@ start of the register dump
+#endif
no_old_VFP_process:
DBGSTR1 "load state %p", r10
- str r10, [r3] @ update the last_VFP_context pointer
+ str r10, [r3, r11, lsl #2] @ update the last_VFP_context pointer
@ Load the saved state back into the VFP
VFPFLDMIA r10 @ reload the working registers while
@ FPEXC is in a safe state
@@ -162,6 +166,24 @@ process_exception:
@ required. If not, the user code will
@ retry the faulted instruction
+#ifdef CONFIG_SMP
+ .globl vfp_save_state
+ .type vfp_save_state, %function
+vfp_save_state:
+ @ Save the current VFP state
+ @ r0 - save location
+ @ r1 - FPEXC
+ DBGSTR1 "save VFP state %p", r0
+ VFPFMRX r2, FPSCR @ current status
+ VFPFMRX r3, FPINST @ FPINST (always there, rev0 onwards)
+ tst r1, #FPEXC_FPV2 @ is there an FPINST2 to read?
+ VFPFMRX r12, FPINST2, NE @ FPINST2 if needed - avoids reading
+ @ nonexistant reg on rev0
+ VFPFSTMIA r0 @ save the working registers
+ stmia r0, {r1, r2, r3, r12} @ save FPEXC, FPSCR, FPINST, FPINST2
+ mov pc, lr
+#endif
+
last_VFP_context_address:
.word last_VFP_context