b86040a59f
This patch implements the ARM/Thumb-2 unified kernel start-up and exception handling code. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
149 lines
3.7 KiB
ArmAsm
149 lines
3.7 KiB
ArmAsm
#include <linux/init.h>
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/asm-offsets.h>
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#include <asm/errno.h>
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#include <asm/thread_info.h>
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@ Bad Abort numbers
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@ -----------------
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@
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#define BAD_PREFETCH 0
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#define BAD_DATA 1
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#define BAD_ADDREXCPTN 2
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#define BAD_IRQ 3
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#define BAD_UNDEFINSTR 4
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@
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@ Most of the stack format comes from struct pt_regs, but with
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@ the addition of 8 bytes for storing syscall args 5 and 6.
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@ This _must_ remain a multiple of 8 for EABI.
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@
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#define S_OFF 8
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/*
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* The SWI code relies on the fact that R0 is at the bottom of the stack
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* (due to slow/fast restore user regs).
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*/
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#if S_R0 != 0
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#error "Please fix"
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#endif
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.macro zero_fp
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#ifdef CONFIG_FRAME_POINTER
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mov fp, #0
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#endif
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.endm
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.macro alignment_trap, rtemp
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#ifdef CONFIG_ALIGNMENT_TRAP
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ldr \rtemp, .LCcralign
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ldr \rtemp, [\rtemp]
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mcr p15, 0, \rtemp, c1, c0
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#endif
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.endm
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@
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@ Store/load the USER SP and LR registers by switching to the SYS
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@ mode. Useful in Thumb-2 mode where "stm/ldm rd, {sp, lr}^" is not
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@ available. Should only be called from SVC mode
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@
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.macro store_user_sp_lr, rd, rtemp, offset = 0
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mrs \rtemp, cpsr
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eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
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msr cpsr_c, \rtemp @ switch to the SYS mode
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str sp, [\rd, #\offset] @ save sp_usr
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str lr, [\rd, #\offset + 4] @ save lr_usr
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eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
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msr cpsr_c, \rtemp @ switch back to the SVC mode
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.endm
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.macro load_user_sp_lr, rd, rtemp, offset = 0
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mrs \rtemp, cpsr
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eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
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msr cpsr_c, \rtemp @ switch to the SYS mode
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ldr sp, [\rd, #\offset] @ load sp_usr
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ldr lr, [\rd, #\offset + 4] @ load lr_usr
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eor \rtemp, \rtemp, #(SVC_MODE ^ SYSTEM_MODE)
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msr cpsr_c, \rtemp @ switch back to the SVC mode
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.endm
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#ifndef CONFIG_THUMB2_KERNEL
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.macro svc_exit, rpsr
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msr spsr_cxsf, \rpsr
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ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr
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.endm
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.macro restore_user_regs, fast = 0, offset = 0
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ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr
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ldr lr, [sp, #\offset + S_PC]! @ get pc
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msr spsr_cxsf, r1 @ save in spsr_svc
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.if \fast
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ldmdb sp, {r1 - lr}^ @ get calling r1 - lr
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.else
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ldmdb sp, {r0 - lr}^ @ get calling r0 - lr
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.endif
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add sp, sp, #S_FRAME_SIZE - S_PC
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movs pc, lr @ return & move spsr_svc into cpsr
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.endm
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.macro get_thread_info, rd
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mov \rd, sp, lsr #13
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mov \rd, \rd, lsl #13
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.endm
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#else /* CONFIG_THUMB2_KERNEL */
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.macro svc_exit, rpsr
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ldr r0, [sp, #S_SP] @ top of the stack
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ldr r1, [sp, #S_PC] @ return address
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tst r0, #4 @ orig stack 8-byte aligned?
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stmdb r0, {r1, \rpsr} @ rfe context
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ldmia sp, {r0 - r12}
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ldr lr, [sp, #S_LR]
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addeq sp, sp, #S_FRAME_SIZE - 8 @ aligned
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addne sp, sp, #S_FRAME_SIZE - 4 @ not aligned
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rfeia sp!
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.endm
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.macro restore_user_regs, fast = 0, offset = 0
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mov r2, sp
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load_user_sp_lr r2, r3, \offset + S_SP @ calling sp, lr
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ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr
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ldr lr, [sp, #\offset + S_PC] @ get pc
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add sp, sp, #\offset + S_SP
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msr spsr_cxsf, r1 @ save in spsr_svc
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.if \fast
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ldmdb sp, {r1 - r12} @ get calling r1 - r12
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.else
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ldmdb sp, {r0 - r12} @ get calling r0 - r12
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.endif
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add sp, sp, #S_FRAME_SIZE - S_SP
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movs pc, lr @ return & move spsr_svc into cpsr
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.endm
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.macro get_thread_info, rd
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mov \rd, sp
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lsr \rd, \rd, #13
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mov \rd, \rd, lsl #13
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.endm
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#endif /* !CONFIG_THUMB2_KERNEL */
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/*
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* These are the registers used in the syscall handler, and allow us to
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* have in theory up to 7 arguments to a function - r0 to r6.
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*
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* r7 is reserved for the system call number for thumb mode.
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*
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* Note that tbl == why is intentional.
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*
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* We must set at least "tsk" and "why" when calling ret_with_reschedule.
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*/
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scno .req r7 @ syscall number
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tbl .req r8 @ syscall table pointer
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why .req r8 @ Linux syscall (!= 0)
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tsk .req r9 @ current thread_info
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