Some updates to SCR can cause a problem which manifests as an undefined opcode exception. This may be when a speculative secure instruction fetch happens after the NS bit is set. An isb is required to make the register change take effect fully.
Contributed-under: Tianocore Contribution Agreement 1.0 Signed-off-by: Evan Lloyd <[email protected]> Reviewed-by: Sami Mujawar <[email protected]> --- diff --git a/ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S b/ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S index 28db98b..50faef4 100644 --- a/ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S +++ b/ArmPkg/Library/ArmLib/Common/AArch64/ArmLibSupport.S @@ -184,6 +184,7 @@ ASM_PFX(ArmWriteCptr): ASM_PFX(ArmWriteScr): msr scr_el3, x0 // Secure configuration register EL3 + isb ret ASM_PFX(ArmWriteMVBar): diff --git a/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.S b/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.S index 43842f3..ffeaed3 100644 --- a/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.S +++ b/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.S @@ -153,6 +153,7 @@ ASM_PFX(ArmReadScr): ASM_PFX(ArmWriteScr): mcr p15, 0, r0, c1, c1, 0 + isb bx lr ASM_PFX(ArmReadHVBar): diff --git a/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.asm b/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.asm index 8864c16..15bfb6e 100644 --- a/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.asm +++ b/ArmPkg/Library/ArmLib/Common/Arm/ArmLibSupport.asm @@ -153,6 +153,7 @@ ArmReadScr ArmWriteScr mcr p15, 0, r0, c1, c1, 0 + isb bx lr ArmReadHVBar -- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. ARM Limited, Registered office 110 Fulbourn Road, Cambridge CB1 9NJ, Registered in England & Wales, Company No: 2557590 ARM Holdings plc, Registered office 110 Fulbourn Road, Cambridge CB1 9NJ, Registered in England & Wales, Company No: 2548782 _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
