Re: [PATCH 1/3] arm64: adjust el0_sync so that a function can be called

On Sun, Apr 27, 2014 at 08:44:12PM +0100, Larry Bassel wrote:

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 39ac630..eda7755 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S

[...]

@@ -421,28 +421,30 @@ el0_da: /* * Data abort handling */

• mrs x0, far_el1
• bic x0, x0, #(0xff << 56) disable_step x1 isb enable_dbg // enable interrupts before calling the main handler enable_irq

• mrs x0, far_el1
• bic x0, x0, #(0xff << 56) mov x1, x25 mov x2, sp
• adr lr, ret_from_exception b do_mem_abort

Reading the far_el1 after enable_dbg and enable_irq is racy, we can no longer guarantee its value in the original data abort context.

el0_ia: /* * Instruction abort handling */

• mrs x0, far_el1 disable_step x1 isb enable_dbg // enable interrupts before calling the main handler enable_irq

• mrs x0, far_el1 orr x1, x25, #1 << 24 // use reserved ISS bit for instruction aborts mov x2, sp
• adr lr, ret_from_exception b do_mem_abort

el0_fpsimd_acc:

Same here.