From 2f08a16b043822ec9011397acf8d2a63e6802c6c Mon Sep 17 00:00:00 2001 From: Wei Chen Date: Wed, 5 Apr 2017 17:09:12 +0800 Subject: [PATCH] xen/arm32: Use alternative to skip the check of pending serrors We have provided an option to administrator to determine how to handle the SErrors. In order to skip the check of pending SError, in conventional way, we have to read the option every time before we try to check the pending SError. This will add overhead to check the option at every trap. The ARM32 supports the alternative patching feature. We can use an ALTERNATIVE to avoid checking option at every trap. We added a new cpufeature named "SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT". This feature will be enabled when the option is not diverse. Signed-off-by: Wei Chen Reviewed-by: Julien Grall --- xen/arch/arm/arm32/entry.S | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/xen/arch/arm/arm32/entry.S b/xen/arch/arm/arm32/entry.S index 2187226b12..8cd21238af 100644 --- a/xen/arch/arm/arm32/entry.S +++ b/xen/arch/arm/arm32/entry.S @@ -1,5 +1,6 @@ #include #include +#include #include #define SAVE_ONE_BANKED(reg) mrs r11, reg; str r11, [sp, #UREGS_##reg] @@ -44,6 +45,14 @@ save_guest_regs: SAVE_BANKED(fiq) SAVE_ONE_BANKED(R8_fiq); SAVE_ONE_BANKED(R9_fiq); SAVE_ONE_BANKED(R10_fiq) SAVE_ONE_BANKED(R11_fiq); SAVE_ONE_BANKED(R12_fiq); + + /* + * If the SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT has been set in the cpu + * feature, the checking of pending SErrors will be skipped. + */ + ALTERNATIVE("nop", + "b skip_check", + SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT) /* * Start to check pending virtual abort in the gap of Guest -> HYP * world switch. @@ -99,6 +108,7 @@ abort_guest_exit_end: */ bne return_from_trap +skip_check: mov pc, lr #define DEFINE_TRAP_ENTRY(trap) \ -- 2.39.5