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authorStephen Boyd <sboyd@codeaurora.org>2013-01-14 19:50:42 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2013-01-16 16:51:10 +0000
commit568dca15aa2a0f4ddee255894ec393a159f13147 (patch)
treef60bbd141dbda5325c1cb005920b43c08f03243e /arch/arm
parent8a3a180d21793f2e4386b3cb61c48322564fc80a (diff)
ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not PREEMPT alone
Patrik Kluba reports that the preempt count becomes invalid due to the preempt_enable() call being unbalanced with a preempt_disable() call in the vfp assembly routines. This happens because preempt_enable() and preempt_disable() update preempt counts under PREEMPT_COUNT=y but the vfp assembly routines do so under PREEMPT=y. In a configuration where PREEMPT=n and DEBUG_ATOMIC_SLEEP=y, PREEMPT_COUNT=y and so the preempt_enable() call in VFP_bounce() keeps subtracting from the preempt count until it goes negative. Fix this by always using PREEMPT_COUNT to decided when to update preempt counts in the ARM assembly code. Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Reported-by: Patrik Kluba <pkluba@dension.com> Tested-by: Patrik Kluba <pkluba@dension.com> Cc: <stable@vger.kernel.org> # 2.6.30 Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/vfp/entry.S6
-rw-r--r--arch/arm/vfp/vfphw.S4
2 files changed, 5 insertions, 5 deletions
diff --git a/arch/arm/vfp/entry.S b/arch/arm/vfp/entry.S
index cc926c98598..323ce1a62bb 100644
--- a/arch/arm/vfp/entry.S
+++ b/arch/arm/vfp/entry.S
@@ -22,7 +22,7 @@
@ IRQs disabled.
@
ENTRY(do_vfp)
-#ifdef CONFIG_PREEMPT
+#ifdef CONFIG_PREEMPT_COUNT
ldr r4, [r10, #TI_PREEMPT] @ get preempt count
add r11, r4, #1 @ increment it
str r11, [r10, #TI_PREEMPT]
@@ -35,7 +35,7 @@ ENTRY(do_vfp)
ENDPROC(do_vfp)
ENTRY(vfp_null_entry)
-#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
@@ -53,7 +53,7 @@ ENDPROC(vfp_null_entry)
__INIT
ENTRY(vfp_testing_entry)
-#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
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
index ea0349f6358..dd5e56f95f3 100644
--- a/arch/arm/vfp/vfphw.S
+++ b/arch/arm/vfp/vfphw.S
@@ -168,7 +168,7 @@ vfp_hw_state_valid:
@ else it's one 32-bit instruction, so
@ always subtract 4 from the following
@ instruction address.
-#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
@@ -192,7 +192,7 @@ 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