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| author | Will Deacon <will.deacon@arm.com> | 2010-11-28 15:57:24 +0100 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2010-12-06 12:55:56 +0100 |
| commit | 7e20269647169e7ea08a62bdc4979a3ba32e615c (patch) | |
| tree | b66a6c5e893a34ee9659403f66f44841dfb34232 /arch/arm/kernel/entry-armv.S | |
| parent | ARM: hw_breakpoint: correct and simplify alignment fixup code (diff) | |
| download | linux-7e20269647169e7ea08a62bdc4979a3ba32e615c.tar.xz linux-7e20269647169e7ea08a62bdc4979a3ba32e615c.zip | |
ARM: hw_breakpoint: disable preemption during debug exception handling
On ARM, debug exceptions occur in the form of data or prefetch aborts.
One difference is that debug exceptions require access to per-cpu banked
registers and data structures which are not saved in the low-level exception
code. For kernels built with CONFIG_PREEMPT, there is an unlikely scenario
that the debug handler ends up running on a different CPU from the one
that originally signalled the event, resulting in random data being read
from the wrong registers.
This patch adds a debug_entry macro to the low-level exception handling
code which checks whether the taken exception is a debug exception. If
it is, the preempt count for the faulting process is incremented. After
the debug handler has finished, the count is decremented.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm/kernel/entry-armv.S')
| -rw-r--r-- | arch/arm/kernel/entry-armv.S | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index c09e3573c5de..34bbef0d2e7e 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -198,6 +198,7 @@ __dabt_svc: @ @ set desired IRQ state, then call main handler @ + debug_entry r1 msr cpsr_c, r9 mov r2, sp bl do_DataAbort @@ -324,6 +325,7 @@ __pabt_svc: #else bl CPU_PABORT_HANDLER #endif + debug_entry r1 msr cpsr_c, r9 @ Maybe enable interrupts mov r2, sp @ regs bl do_PrefetchAbort @ call abort handler @@ -439,6 +441,7 @@ __dabt_usr: @ @ IRQs on, then call the main handler @ + debug_entry r1 enable_irq mov r2, sp adr lr, BSYM(ret_from_exception) @@ -703,6 +706,7 @@ __pabt_usr: #else bl CPU_PABORT_HANDLER #endif + debug_entry r1 enable_irq @ Enable interrupts mov r2, sp @ regs bl do_PrefetchAbort @ call abort handler |