| From 568dca15aa2a0f4ddee255894ec393a159f13147 Mon Sep 17 00:00:00 2001 |
| From: Stephen Boyd <sboyd@codeaurora.org> |
| Date: Mon, 14 Jan 2013 19:50:42 +0100 |
| Subject: ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not PREEMPT alone |
| |
| From: Stephen Boyd <sboyd@codeaurora.org> |
| |
| commit 568dca15aa2a0f4ddee255894ec393a159f13147 upstream. |
| |
| 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> |
| Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/arm/vfp/entry.S | 6 +++--- |
| arch/arm/vfp/vfphw.S | 4 ++-- |
| 2 files changed, 5 insertions(+), 5 deletions(-) |
| |
| --- 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 |
| --- 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 |
