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authorRussell King <rmk+kernel@arm.linux.org.uk>2010-02-06 14:27:45 +0300
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-02-16 00:39:53 +0300
commit54cb3dbb4a1cccd6b1bffc169ff638f8e74daf44 (patch)
tree454b05810dc96b288eabcc4e11046adb0bc8b8ec /arch/arm/vfp
parent462f39a8c7496c95f4de91ef46d875f46e0fa271 (diff)
downloadlinux-54cb3dbb4a1cccd6b1bffc169ff638f8e74daf44.tar.xz
ARM: vfp: fix vfp_sync_state()
The more I look at vfp_sync_state(), the more I believe it's trying to do its job in a really obscure way. Essentially, last_VFP_context[] tracks who owns the state in the VFP hardware. If last_VFP_context[] is the context for the thread which we're interested in, then the VFP hardware has context which is not saved in the software state - so we need to bring the software state up to date. If last_VFP_context[] is for some other thread, we really don't care what state the VFP hardware is in; it doesn't contain any information pertinent to the thread we're trying to deal with - so don't touch the hardware. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/vfp')
-rw-r--r--arch/arm/vfp/vfpmodule.c36
1 files changed, 16 insertions, 20 deletions
diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c
index f60a5400a25b..86a57aeeda4a 100644
--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
@@ -444,32 +444,28 @@ void vfp_sync_state(struct thread_info *thread)
void vfp_sync_state(struct thread_info *thread)
{
unsigned int cpu = get_cpu();
- u32 fpexc = fmrx(FPEXC);
/*
- * If VFP is enabled, the previous state was already saved and
- * last_VFP_context updated.
+ * If the thread we're interested in is the current owner of the
+ * hardware VFP state, then we need to save its state.
*/
- if (fpexc & FPEXC_EN)
- goto out;
-
- if (!last_VFP_context[cpu])
- goto out;
+ if (last_VFP_context[cpu] == &thread->vfpstate) {
+ u32 fpexc = fmrx(FPEXC);
- /*
- * Save the last VFP state on this CPU.
- */
- fmxr(FPEXC, fpexc | FPEXC_EN);
- vfp_save_state(last_VFP_context[cpu], fpexc);
- fmxr(FPEXC, fpexc);
+ /*
+ * Save the last VFP state on this CPU.
+ */
+ fmxr(FPEXC, fpexc | FPEXC_EN);
+ vfp_save_state(&thread->vfpstate, fpexc | FPEXC_EN);
+ fmxr(FPEXC, fpexc & ~FPEXC_EN);
- /*
- * Set the context to NULL to force a reload the next time the thread
- * uses the VFP.
- */
- last_VFP_context[cpu] = NULL;
+ /*
+ * Set the context to NULL to force a reload the next time
+ * the thread uses the VFP.
+ */
+ last_VFP_context[cpu] = NULL;
+ }
-out:
put_cpu();
}
#endif