From 78ad457b2dbd0fe6cdc7ea42a69774a72ed007b9 Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Mon, 27 Nov 2017 00:47:09 +0000 Subject: [PATCH] armv8: shrink exception table code In the moment our exception entry code needs 34 instructions, so we can't use put it directly into the table entry, which offers "only" 32 instructions there. Right now we just put an unconditional branch there, then use a macro to place the 34 instructions *per entry* after that. That effectivly doubles the size of our exception table, which is quite a waste, given that we use it mostly for debugging purposes. Since the register saving part is actually identical, let's just convert that macro into a function, and "bl" into it directly from the exception slot, of course after having saved at least the original LR. This saves us about 950 bytes of code, which is quite a relief for some tight SPLs, in particular the 64-bit Allwinner ones. Signed-off-by: Andre Przywara --- arch/arm/cpu/armv8/exceptions.S | 129 +++++++++++++++++----------------------- 1 file changed, 56 insertions(+), 73 deletions(-) diff --git a/arch/arm/cpu/armv8/exceptions.S b/arch/arm/cpu/armv8/exceptions.S index 4f4f526..8c7c1d3 100644 --- a/arch/arm/cpu/armv8/exceptions.S +++ b/arch/arm/cpu/armv8/exceptions.S @@ -12,12 +12,65 @@ #include /* + * Exception vectors. + */ + .align 11 + .globl vectors +vectors: + .align 7 /* Current EL Synchronous Thread */ + stp x29, x30, [sp, #-16]! + bl _exception_entry + bl do_bad_sync + b exception_exit + + .align 7 /* Current EL IRQ Thread */ + stp x29, x30, [sp, #-16]! + bl _exception_entry + bl do_bad_irq + b exception_exit + + .align 7 /* Current EL FIQ Thread */ + stp x29, x30, [sp, #-16]! + bl _exception_entry + bl do_bad_fiq + b exception_exit + + .align 7 /* Current EL Error Thread */ + stp x29, x30, [sp, #-16]! + bl _exception_entry + bl do_bad_error + b exception_exit + + .align 7 /* Current EL Synchronous Handler */ + stp x29, x30, [sp, #-16]! + bl _exception_entry + bl do_sync + b exception_exit + + .align 7 /* Current EL IRQ Handler */ + stp x29, x30, [sp, #-16]! + bl _exception_entry + bl do_irq + b exception_exit + + .align 7 /* Current EL FIQ Handler */ + stp x29, x30, [sp, #-16]! + bl _exception_entry + bl do_fiq + b exception_exit + + .align 7 /* Current EL Error Handler */ + stp x29, x30, [sp, #-16]! + bl _exception_entry + bl do_error + b exception_exit + +/* * Enter Exception. * This will save the processor state that is ELR/X0~X30 * to the stack frame. */ -.macro exception_entry - stp x29, x30, [sp, #-16]! +_exception_entry: stp x27, x28, [sp, #-16]! stp x25, x26, [sp, #-16]! stp x23, x24, [sp, #-16]! @@ -46,78 +99,8 @@ 0: stp x2, x0, [sp, #-16]! mov x0, sp -.endm + ret -/* - * Exception vectors. - */ - .align 11 - .globl vectors -vectors: - .align 7 - b _do_bad_sync /* Current EL Synchronous Thread */ - - .align 7 - b _do_bad_irq /* Current EL IRQ Thread */ - - .align 7 - b _do_bad_fiq /* Current EL FIQ Thread */ - - .align 7 - b _do_bad_error /* Current EL Error Thread */ - - .align 7 - b _do_sync /* Current EL Synchronous Handler */ - - .align 7 - b _do_irq /* Current EL IRQ Handler */ - - .align 7 - b _do_fiq /* Current EL FIQ Handler */ - - .align 7 - b _do_error /* Current EL Error Handler */ - - -_do_bad_sync: - exception_entry - bl do_bad_sync - b exception_exit - -_do_bad_irq: - exception_entry - bl do_bad_irq - b exception_exit - -_do_bad_fiq: - exception_entry - bl do_bad_fiq - b exception_exit - -_do_bad_error: - exception_entry - bl do_bad_error - b exception_exit - -_do_sync: - exception_entry - bl do_sync - b exception_exit - -_do_irq: - exception_entry - bl do_irq - b exception_exit - -_do_fiq: - exception_entry - bl do_fiq - b exception_exit - -_do_error: - exception_entry - bl do_error - b exception_exit exception_exit: ldp x2, x0, [sp],#16