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| author |  Ard Biesheuvel <ardb@kernel.org>
| 2023-04-12 09:50:20 +0100 |
|---|---|---|
| committer |  Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
| 2023-04-12 10:04:56 +0100 |
| commit | c76c6c4ecbec0deb56a4f9e932b26866024a508f (patch) | |
| tree | e6da7ee937a9e9ee7b29dcab602a24d2ee974714 /arch/arm/vfp/vfphw.S | |
| parent | ARM: 9293/1: vfp: Pass successful return address via register R3 (diff) | |
| download | linux-c76c6c4ecbec0deb56a4f9e932b26866024a508f.tar.gz linux-c76c6c4ecbec0deb56a4f9e932b26866024a508f.tar.bz2 linux-c76c6c4ecbec0deb56a4f9e932b26866024a508f.zip | |
ARM: 9294/2: vfp: Fix broken softirq handling with instrumentation enabled
Commit 62b95a7b44d1 ("ARM: 9282/1: vfp: Manipulate task VFP state with
softirqs disabled") replaced the en/disable preemption calls inside the
VFP state handling code with en/disabling of soft IRQs, which is
necessary to allow kernel use of the VFP/SIMD unit when handling a soft
IRQ.
Unfortunately, when lockdep is enabled (or other instrumentation that
enables TRACE_IRQFLAGS), the disable path implemented in asm fails to
perform the lockdep and RCU related bookkeeping, resulting in spurious
warnings and other badness.
Set let's rework the VFP entry code a little bit so we can make the
local_bh_disable() call from C, with all the instrumentations that
happen to have been configured. Calling local_bh_enable() can be done
from asm, as it is a simple wrapper around __local_bh_enable_ip(), which
is always a callable function.
Link: https://lore.kernel.org/all/ZBBYCSZUJOWBg1s8@localhost.localdomain/
Fixes: 62b95a7b44d1 ("ARM: 9282/1: vfp: Manipulate task VFP state with softirqs disabled")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch/arm/vfp/vfphw.S')
| -rw-r--r-- | arch/arm/vfp/vfphw.S | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S index 60acd42e0578..4d8478264d82 100644 --- a/arch/arm/vfp/vfphw.S +++ b/arch/arm/vfp/vfphw.S @@ -75,8 +75,6 @@ @ lr = unrecognised instruction return address @ IRQs enabled. ENTRY(vfp_support_entry) - local_bh_disable r1, r4 - ldr r11, [r1, #TI_CPU] @ CPU number add r10, r1, #TI_VFPSTATE @ r10 = workspace @@ -179,9 +177,12 @@ vfp_hw_state_valid: @ else it's one 32-bit instruction, so @ always subtract 4 from the following @ instruction address. - local_bh_enable_ti r10, r4 - ret r3 @ we think we have handled things + mov lr, r3 @ we think we have handled things +local_bh_enable_and_ret: + adr r0, . + mov r1, #SOFTIRQ_DISABLE_OFFSET + b __local_bh_enable_ip @ tail call look_for_VFP_exceptions: @ Check for synchronous or asynchronous exception @@ -204,8 +205,7 @@ skip: @ not recognised by VFP DBGSTR "not VFP" - local_bh_enable_ti r10, r4 - ret lr + b local_bh_enable_and_ret process_exception: DBGSTR "bounce" |