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Diffstat (limited to 'src/arch/arm64/transition_asm.S')
| -rw-r--r-- | src/arch/arm64/transition_asm.S | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/src/arch/arm64/transition_asm.S b/src/arch/arm64/transition_asm.S new file mode 100644 index 0000000000..9f48549028 --- /dev/null +++ b/src/arch/arm64/transition_asm.S @@ -0,0 +1,169 @@ +/* + * This file is part of the coreboot project. + * + * Copyright 2014 Google Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/* + * transition_asm.S: This file handles the entry and exit from an exception + * + * Flow: exception --> exc_vectors --> exc_entry --> exc_dispatch --> + * exc_exit + * Transition Flow: transition --> trans_switch --> exc_exit + * + * |---| Exception Entry |---| + * + * On exception entry, it saves all the xregs on SP_ELx since SP_ELx is + * selected on entry. Some dummy pushes are performed to create space for + * elx_state structure. It then passes pointer to this saved set of regs and + * a unique id(for identifying exception) to exc_entry. + * + * |---| Exception Transition Dispatch |---| + * + * This is the C-component of exception entry. It does the work of initializing + * the exc_state registers. Finally it calls exception dispatch implemented by + * the user. This is point of no-return. + * + * |---| Exception Dispatch |---| + * + * User of this functionality is expected to implement exc_dispatch which + * acts as entry point for it. Once exception handling is complete, the user + * needs to call exc_exit with pointer to struct regs. + * + * |---| Exception Exit |---| + * + * Once exc_dispatch is done with handling the exception based on the id passed + * to it, it needs to call exc_exit with pointer to struct regs. This is done to + * unwind the exception stack by popping off all the xregs. + * + * |---| Exception Transition Exit |---| + * + * This routine makes SP_EL0 point to the regs structure passed and continues + * onto the exception exit routine described above. This is the reason that + * transition library does not handle initialization of SP_EL0 for the program + * to be executed. + */ + +#define __ASSEMBLY__ +#include <arch/asm.h> +#include <arch/lib_helpers.h> +#include <arch/transition.h> + +.macro eentry lbl id + .align 7 +\lbl: + stp x29, x30, [sp, #STACK_PUSH_BYTES]! + bl exc_prologue + mov x1, \id + mov x0, sp + b exc_entry +.endm + +/* + * exc_vectors: Entry point for an exception + */ +ENTRY_WITH_ALIGN(exc_vectors, 11) + +eentry sync_curr_sp0,#0 +eentry irq_curr_sp0,#1 +eentry fiq_curr_sp0,#2 +eentry serror_curr_sp0,#3 +eentry sync_curr_spx,#4 +eentry irq_curr_spx,#5 +eentry fiq_curr_spx,#6 +eentry serror_curr_spx,#7 +eentry sync_lower_64,#8 +eentry irq_lower_64,#9 +eentry fiq_lower_64,#10 +eentry serror_lower_64,#11 +eentry sync_lower_32,#12 +eentry irq_lower_32,#13 +eentry fiq_lower_32,#14 +eentry serror_lower_32,#15 + +ENDPROC(exc_vectors) + +ENTRY(exc_prologue) + stp x27, x28, [sp, #STACK_PUSH_BYTES]! + stp x25, x26, [sp, #STACK_PUSH_BYTES]! + stp x23, x24, [sp, #STACK_PUSH_BYTES]! + stp x21, x22, [sp, #STACK_PUSH_BYTES]! + stp x19, x20, [sp, #STACK_PUSH_BYTES]! + stp x17, x18, [sp, #STACK_PUSH_BYTES]! + stp x15, x16, [sp, #STACK_PUSH_BYTES]! + stp x13, x14, [sp, #STACK_PUSH_BYTES]! + stp x11, x12, [sp, #STACK_PUSH_BYTES]! + stp x9, x10, [sp, #STACK_PUSH_BYTES]! + stp x7, x8, [sp, #STACK_PUSH_BYTES]! + stp x5, x6, [sp, #STACK_PUSH_BYTES]! + stp x3, x4, [sp, #STACK_PUSH_BYTES]! + stp x1, x2, [sp, #STACK_PUSH_BYTES]! + /* xzr pushed as place holder for sp */ + stp xzr, x0, [sp, #STACK_PUSH_BYTES]! + /* + * xzr pushed as place holder for: + * 1. sp_elx and elr + */ + stp xzr, xzr, [sp, #STACK_PUSH_BYTES]! + /* 2. spsr and sp_el0 */ + stp xzr, xzr, [sp, #STACK_PUSH_BYTES]! + ret +ENDPROC(exc_prologue) + +/* + * trans_switch: Set SPSel to use SP_EL0 + * x0 = regs structure + */ +ENTRY(trans_switch) + msr SPSel, #SPSR_USE_L + b exc_exit +ENDPROC(trans_switch) + +/* + * exc_exit: Return from exception by restoring saved state of xregs + * x0 = regs structure + */ +ENTRY(exc_exit) + /* Unwind the stack by making sp point to regs structure */ + mov sp, x0 + /* Load registers x0-x30 */ + ldp xzr, x0, [sp], #STACK_POP_BYTES + ldp x1, x2, [sp], #STACK_POP_BYTES + ldp x3, x4, [sp], #STACK_POP_BYTES + ldp x5, x6, [sp], #STACK_POP_BYTES + ldp x7, x8, [sp], #STACK_POP_BYTES + ldp x9, x10, [sp], #STACK_POP_BYTES + ldp x11, x12, [sp], #STACK_POP_BYTES + ldp x13, x14, [sp], #STACK_POP_BYTES + ldp x15, x16, [sp], #STACK_POP_BYTES + ldp x17, x18, [sp], #STACK_POP_BYTES + ldp x19, x20, [sp], #STACK_POP_BYTES + ldp x21, x22, [sp], #STACK_POP_BYTES + ldp x23, x24, [sp], #STACK_POP_BYTES + ldp x25, x26, [sp], #STACK_POP_BYTES + ldp x27, x28, [sp], #STACK_POP_BYTES + ldp x29, x30, [sp], #STACK_POP_BYTES + eret +ENDPROC(exc_exit) + +/* exc_set_vbar: Initialize the exception entry address in vbar */ +ENTRY(exc_set_vbar) + adr x0, exc_vectors + write_current vbar, x0, x1 + dsb sy + isb + ret +ENDPROC(exc_set_vbar) |