X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;ds=sidebyside;f=arch%2Farm%2Fvfp%2Fvfphw.S;h=2d30c7f6edd32ddd5b93e6b8356ae679ce983041;hb=6fd4ce886440c7a1b08b6642e606ee19097829df;hp=9897dcfc16d67a0e104552814adaad8ec1230e32;hpb=eee2a817df7c5a6e569f353f8be78cc1b3604bb6;p=pandora-kernel.git

diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
index 9897dcfc16d6..2d30c7f6edd3 100644
--- a/arch/arm/vfp/vfphw.S
+++ b/arch/arm/vfp/vfphw.S
@@ -77,27 +77,27 @@ ENTRY(vfp_support_entry)
 	bne	look_for_VFP_exceptions	@ VFP is already enabled
 
 	DBGSTR1 "enable %x", r10
-	ldr	r3, last_VFP_context_address
+	ldr	r3, vfp_current_hw_state_address
 	orr	r1, r1, #FPEXC_EN	@ user FPEXC has the enable bit set
-	ldr	r4, [r3, r11, lsl #2]	@ last_VFP_context pointer
+	ldr	r4, [r3, r11, lsl #2]	@ vfp_current_hw_state pointer
 	bic	r5, r1, #FPEXC_EX	@ make sure exceptions are disabled
-	cmp	r4, r10
-	beq	check_for_exception	@ we are returning to the same
-					@ process, so the registers are
-					@ still there.  In this case, we do
-					@ not want to drop a pending exception.
+	cmp	r4, r10			@ this thread owns the hw context?
+#ifndef CONFIG_SMP
+	@ For UP, checking that this thread owns the hw context is
+	@ sufficient to determine that the hardware state is valid.
+	beq	vfp_hw_state_valid
+
+	@ On UP, we lazily save the VFP context.  As a different
+	@ thread wants ownership of the VFP hardware, save the old
+	@ state if there was a previous (valid) owner.
 
 	VFPFMXR	FPEXC, r5		@ enable VFP, disable any pending
 					@ 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
-	beq	no_old_VFP_process
+	cmp	r4, #0			@ if the vfp_current_hw_state is NULL
+	beq	vfp_reload_hw		@ then the hw state needs reloading
 	VFPFSTMIA r4, r5		@ save the working registers
 	VFPFMRX	r5, FPSCR		@ current status
 #ifndef CONFIG_CPU_FEROCEON
@@ -110,13 +110,35 @@ ENTRY(vfp_support_entry)
 1:
 #endif
 	stmia	r4, {r1, r5, r6, r8}	@ save FPEXC, FPSCR, FPINST, FPINST2
-					@ and point r4 at the word at the
-					@ start of the register dump
+vfp_reload_hw:
+
+#else
+	@ For SMP, if this thread does not own the hw context, then we
+	@ need to reload it.  No need to save the old state as on SMP,
+	@ we always save the state when we switch away from a thread.
+	bne	vfp_reload_hw
+
+	@ This thread has ownership of the current hardware context.
+	@ However, it may have been migrated to another CPU, in which
+	@ case the saved state is newer than the hardware context.
+	@ Check this by looking at the CPU number which the state was
+	@ last loaded onto.
+	ldr	ip, [r10, #VFP_CPU]
+	teq	ip, r11
+	beq	vfp_hw_state_valid
+
+vfp_reload_hw:
+	@ We're loading this threads state into the VFP hardware. Update
+	@ the CPU number which contains the most up to date VFP context.
+	str	r11, [r10, #VFP_CPU]
+
+	VFPFMXR	FPEXC, r5		@ enable VFP, disable any pending
+					@ exceptions, so we can get at the
+					@ rest of it
 #endif
 
-no_old_VFP_process:
 	DBGSTR1	"load state %p", r10
-	str	r10, [r3, r11, lsl #2]	@ update the last_VFP_context pointer
+	str	r10, [r3, r11, lsl #2]	@ update the vfp_current_hw_state pointer
 					@ Load the saved state back into the VFP
 	VFPFLDMIA r10, r5		@ reload the working registers while
 					@ FPEXC is in a safe state
@@ -132,7 +154,8 @@ no_old_VFP_process:
 #endif
 	VFPFMXR	FPSCR, r5		@ restore status
 
-check_for_exception:
+@ The context stored in the VFP hardware is up to date with this thread
+vfp_hw_state_valid:
 	tst	r1, #FPEXC_EX
 	bne	process_exception	@ might as well handle the pending
 					@ exception before retrying branch
@@ -207,8 +230,8 @@ ENTRY(vfp_save_state)
 ENDPROC(vfp_save_state)
 
 	.align
-last_VFP_context_address:
-	.word	last_VFP_context
+vfp_current_hw_state_address:
+	.word	vfp_current_hw_state
 
 	.macro	tbl_branch, base, tmp, shift
 #ifdef CONFIG_THUMB2_KERNEL