From 36c64c664ba18026aad5375dbb80118bd3141266 Mon Sep 17 00:00:00 2001 From: Heyi Guo Date: Thu, 24 Sep 2015 17:05:39 +0000 Subject: [PATCH] ArmPkg/CpuDxe: Disable interrupt before restoring context Interrupt must be disabled before we storing ELR and other system registers, or else ELR will be overridden by interrupt reentrance. This bug is critical as we may get occasional exception or dead loop when interrupt reentrance occurs: After increasing SP ... Before popping out registers Or After restoring ELR The 1st circumstance could also be resolved by optimizing SP operation (Pop out registers before adding SP back), but the 2nd could not be resolved by disabling interrupt. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Heyi Guo Reviewed-by: Ard Biesheuvel git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18538 6f19259b-4bc3-4df7-8a09-765794883524 --- ArmPkg/Drivers/CpuDxe/AArch64/ExceptionSupport.S | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/ArmPkg/Drivers/CpuDxe/AArch64/ExceptionSupport.S b/ArmPkg/Drivers/CpuDxe/AArch64/ExceptionSupport.S index 2682f4fe75..ca6c9a1522 100644 --- a/ArmPkg/Drivers/CpuDxe/AArch64/ExceptionSupport.S +++ b/ArmPkg/Drivers/CpuDxe/AArch64/ExceptionSupport.S @@ -358,6 +358,14 @@ ASM_PFX(AsmCommonExceptionEntry): #define REG_PAIR(REG1, REG2, OFFSET, CONTEXT_SIZE) ldp REG1, REG2, [sp, #(OFFSET-CONTEXT_SIZE)] #define REG_ONE(REG1, OFFSET, CONTEXT_SIZE) ldur REG1, [sp, #(OFFSET-CONTEXT_SIZE)] + // + // Disable interrupt(IRQ and FIQ) before restoring context, + // or else the context will be corrupted by interrupt reentrance. + // Interrupt mask will be restored from spsr by hardware when we call eret + // + msr daifset, #3 + isb + // Adjust SP to pop system registers add sp, sp, #(GP_CONTEXT_SIZE + FP_CONTEXT_SIZE + SYS_CONTEXT_SIZE) ALL_SYS_REGS -- 2.39.2