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Diffstat (limited to 'arch/openrisc/kernel/entry.S')
| -rw-r--r-- | arch/openrisc/kernel/entry.S | 1128 |
1 files changed, 1128 insertions, 0 deletions
diff --git a/arch/openrisc/kernel/entry.S b/arch/openrisc/kernel/entry.S new file mode 100644 index 0000000..d5f9c35 --- /dev/null +++ b/arch/openrisc/kernel/entry.S @@ -0,0 +1,1128 @@ +/* + * OpenRISC entry.S + * + * Linux architectural port borrowing liberally from similar works of + * others. All original copyrights apply as per the original source + * declaration. + * + * Modifications for the OpenRISC architecture: + * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> + * Copyright (C) 2005 Gyorgy Jeney <nog@bsemi.com> + * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> + * + * 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; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <linux/linkage.h> + +#include <asm/processor.h> +#include <asm/unistd.h> +#include <asm/thread_info.h> +#include <asm/errno.h> +#include <asm/spr_defs.h> +#include <asm/page.h> +#include <asm/mmu.h> +#include <asm/pgtable.h> +#include <asm/asm-offsets.h> + +#define DISABLE_INTERRUPTS(t1,t2) \ + l.mfspr t2,r0,SPR_SR ;\ + l.movhi t1,hi(~(SPR_SR_IEE|SPR_SR_TEE)) ;\ + l.ori t1,t1,lo(~(SPR_SR_IEE|SPR_SR_TEE)) ;\ + l.and t2,t2,t1 ;\ + l.mtspr r0,t2,SPR_SR + +#define ENABLE_INTERRUPTS(t1) \ + l.mfspr t1,r0,SPR_SR ;\ + l.ori t1,t1,lo(SPR_SR_IEE|SPR_SR_TEE) ;\ + l.mtspr r0,t1,SPR_SR + +/* =========================================================[ macros ]=== */ + +/* + * We need to disable interrupts at beginning of RESTORE_ALL + * since interrupt might come in after we've loaded EPC return address + * and overwrite EPC with address somewhere in RESTORE_ALL + * which is of course wrong! + */ + +#define RESTORE_ALL \ + DISABLE_INTERRUPTS(r3,r4) ;\ + l.lwz r3,PT_PC(r1) ;\ + l.mtspr r0,r3,SPR_EPCR_BASE ;\ + l.lwz r3,PT_SR(r1) ;\ + l.mtspr r0,r3,SPR_ESR_BASE ;\ + l.lwz r2,PT_GPR2(r1) ;\ + l.lwz r3,PT_GPR3(r1) ;\ + l.lwz r4,PT_GPR4(r1) ;\ + l.lwz r5,PT_GPR5(r1) ;\ + l.lwz r6,PT_GPR6(r1) ;\ + l.lwz r7,PT_GPR7(r1) ;\ + l.lwz r8,PT_GPR8(r1) ;\ + l.lwz r9,PT_GPR9(r1) ;\ + l.lwz r10,PT_GPR10(r1) ;\ + l.lwz r11,PT_GPR11(r1) ;\ + l.lwz r12,PT_GPR12(r1) ;\ + l.lwz r13,PT_GPR13(r1) ;\ + l.lwz r14,PT_GPR14(r1) ;\ + l.lwz r15,PT_GPR15(r1) ;\ + l.lwz r16,PT_GPR16(r1) ;\ + l.lwz r17,PT_GPR17(r1) ;\ + l.lwz r18,PT_GPR18(r1) ;\ + l.lwz r19,PT_GPR19(r1) ;\ + l.lwz r20,PT_GPR20(r1) ;\ + l.lwz r21,PT_GPR21(r1) ;\ + l.lwz r22,PT_GPR22(r1) ;\ + l.lwz r23,PT_GPR23(r1) ;\ + l.lwz r24,PT_GPR24(r1) ;\ + l.lwz r25,PT_GPR25(r1) ;\ + l.lwz r26,PT_GPR26(r1) ;\ + l.lwz r27,PT_GPR27(r1) ;\ + l.lwz r28,PT_GPR28(r1) ;\ + l.lwz r29,PT_GPR29(r1) ;\ + l.lwz r30,PT_GPR30(r1) ;\ + l.lwz r31,PT_GPR31(r1) ;\ + l.lwz r1,PT_SP(r1) ;\ + l.rfe + + +#define EXCEPTION_ENTRY(handler) \ + .global handler ;\ +handler: ;\ + /* r1, EPCR, ESR a already saved */ ;\ + l.sw PT_GPR2(r1),r2 ;\ + l.sw PT_GPR3(r1),r3 ;\ + l.sw PT_ORIG_GPR11(r1),r11 ;\ + /* r4 already save */ ;\ + l.sw PT_GPR5(r1),r5 ;\ + l.sw PT_GPR6(r1),r6 ;\ + l.sw PT_GPR7(r1),r7 ;\ + l.sw PT_GPR8(r1),r8 ;\ + l.sw PT_GPR9(r1),r9 ;\ + /* r10 already saved */ ;\ + l.sw PT_GPR11(r1),r11 ;\ + /* r12 already saved */ ;\ + l.sw PT_GPR13(r1),r13 ;\ + l.sw PT_GPR14(r1),r14 ;\ + l.sw PT_GPR15(r1),r15 ;\ + l.sw PT_GPR16(r1),r16 ;\ + l.sw PT_GPR17(r1),r17 ;\ + l.sw PT_GPR18(r1),r18 ;\ + l.sw PT_GPR19(r1),r19 ;\ + l.sw PT_GPR20(r1),r20 ;\ + l.sw PT_GPR21(r1),r21 ;\ + l.sw PT_GPR22(r1),r22 ;\ + l.sw PT_GPR23(r1),r23 ;\ + l.sw PT_GPR24(r1),r24 ;\ + l.sw PT_GPR25(r1),r25 ;\ + l.sw PT_GPR26(r1),r26 ;\ + l.sw PT_GPR27(r1),r27 ;\ + l.sw PT_GPR28(r1),r28 ;\ + l.sw PT_GPR29(r1),r29 ;\ + /* r30 already save */ ;\ +/* l.sw PT_GPR30(r1),r30*/ ;\ + l.sw PT_GPR31(r1),r31 ;\ + l.sw PT_SYSCALLNO(r1),r0 + +#define UNHANDLED_EXCEPTION(handler,vector) \ + .global handler ;\ +handler: ;\ + /* r1, EPCR, ESR already saved */ ;\ + l.sw PT_GPR2(r1),r2 ;\ + l.sw PT_GPR3(r1),r3 ;\ + l.sw PT_ORIG_GPR11(r1),r11 ;\ + l.sw PT_GPR5(r1),r5 ;\ + l.sw PT_GPR6(r1),r6 ;\ + l.sw PT_GPR7(r1),r7 ;\ + l.sw PT_GPR8(r1),r8 ;\ + l.sw PT_GPR9(r1),r9 ;\ + /* r10 already saved */ ;\ + l.sw PT_GPR11(r1),r11 ;\ + /* r12 already saved */ ;\ + l.sw PT_GPR13(r1),r13 ;\ + l.sw PT_GPR14(r1),r14 ;\ + l.sw PT_GPR15(r1),r15 ;\ + l.sw PT_GPR16(r1),r16 ;\ + l.sw PT_GPR17(r1),r17 ;\ + l.sw PT_GPR18(r1),r18 ;\ + l.sw PT_GPR19(r1),r19 ;\ + l.sw PT_GPR20(r1),r20 ;\ + l.sw PT_GPR21(r1),r21 ;\ + l.sw PT_GPR22(r1),r22 ;\ + l.sw PT_GPR23(r1),r23 ;\ + l.sw PT_GPR24(r1),r24 ;\ + l.sw PT_GPR25(r1),r25 ;\ + l.sw PT_GPR26(r1),r26 ;\ + l.sw PT_GPR27(r1),r27 ;\ + l.sw PT_GPR28(r1),r28 ;\ + l.sw PT_GPR29(r1),r29 ;\ + /* r31 already saved */ ;\ + l.sw PT_GPR30(r1),r30 ;\ +/* l.sw PT_GPR31(r1),r31 */ ;\ + l.sw PT_SYSCALLNO(r1),r0 ;\ + l.addi r3,r1,0 ;\ + /* r4 is exception EA */ ;\ + l.addi r5,r0,vector ;\ + l.jal unhandled_exception ;\ + l.nop ;\ + l.j _ret_from_exception ;\ + l.nop + +/* + * NOTE: one should never assume that SPR_EPC, SPR_ESR, SPR_EEAR + * contain the same values as when exception we're handling + * occured. in fact they never do. if you need them use + * values saved on stack (for SPR_EPC, SPR_ESR) or content + * of r4 (for SPR_EEAR). for details look at EXCEPTION_HANDLE() + * in 'arch/or32/kernel/head.S' + */ + +/* =====================================================[ exceptions] === */ + +/* ---[ 0x100: RESET exception ]----------------------------------------- */ + +EXCEPTION_ENTRY(_tng_kernel_start) + l.jal _start + l.andi r0,r0,0 + +/* ---[ 0x200: BUS exception ]------------------------------------------- */ + +EXCEPTION_ENTRY(_bus_fault_handler) + /* r4: EA of fault (set by EXCEPTION_HANDLE) */ + l.jal do_bus_fault + l.addi r3,r1,0 /* pt_regs */ + + l.j _ret_from_exception + l.nop + +/* ---[ 0x300: Data Page Fault exception ]------------------------------- */ + +EXCEPTION_ENTRY(_data_page_fault_handler) + /* set up parameters for do_page_fault */ + l.addi r3,r1,0 // pt_regs + /* r4 set be EXCEPTION_HANDLE */ // effective address of fault + l.ori r5,r0,0x300 // exception vector + + /* + * __PHX__: TODO + * + * all this can be written much simpler. look at + * DTLB miss handler in the CONFIG_GUARD_PROTECTED_CORE part + */ +#ifdef CONFIG_OPENRISC_NO_SPR_SR_DSX + l.lwz r6,PT_PC(r3) // address of an offending insn + l.lwz r6,0(r6) // instruction that caused pf + + l.srli r6,r6,26 // check opcode for jump insn + l.sfeqi r6,0 // l.j + l.bf 8f + l.sfeqi r6,1 // l.jal + l.bf 8f + l.sfeqi r6,3 // l.bnf + l.bf 8f + l.sfeqi r6,4 // l.bf + l.bf 8f + l.sfeqi r6,0x11 // l.jr + l.bf 8f + l.sfeqi r6,0x12 // l.jalr + l.bf 8f + + l.nop + + l.j 9f + l.nop +8: + + l.lwz r6,PT_PC(r3) // address of an offending insn + l.addi r6,r6,4 + l.lwz r6,0(r6) // instruction that caused pf + l.srli r6,r6,26 // get opcode +9: + +#else + + l.mfspr r6,r0,SPR_SR // SR +// l.lwz r6,PT_SR(r3) // ESR + l.andi r6,r6,SPR_SR_DSX // check for delay slot exception + l.sfeqi r6,0x1 // exception happened in delay slot + l.bnf 7f + l.lwz r6,PT_PC(r3) // address of an offending insn + + l.addi r6,r6,4 // offending insn is in delay slot +7: + l.lwz r6,0(r6) // instruction that caused pf + l.srli r6,r6,26 // check opcode for write access +#endif + + l.sfgeui r6,0x34 // check opcode for write access + l.bnf 1f + l.sfleui r6,0x37 + l.bnf 1f + l.ori r6,r0,0x1 // write access + l.j 2f + l.nop +1: l.ori r6,r0,0x0 // !write access +2: + + /* call fault.c handler in or32/mm/fault.c */ + l.jal do_page_fault + l.nop + l.j _ret_from_exception + l.nop + +/* ---[ 0x400: Insn Page Fault exception ]------------------------------- */ + +EXCEPTION_ENTRY(_insn_page_fault_handler) + /* set up parameters for do_page_fault */ + l.addi r3,r1,0 // pt_regs + /* r4 set be EXCEPTION_HANDLE */ // effective address of fault + l.ori r5,r0,0x400 // exception vector + l.ori r6,r0,0x0 // !write access + + /* call fault.c handler in or32/mm/fault.c */ + l.jal do_page_fault + l.nop + l.j _ret_from_exception + l.nop + + +/* ---[ 0x500: Timer exception ]----------------------------------------- */ + +EXCEPTION_ENTRY(_timer_handler) + l.jal timer_interrupt + l.addi r3,r1,0 /* pt_regs */ + + l.j _ret_from_intr + l.nop + +/* ---[ 0x600: Aligment exception ]-------------------------------------- */ + +EXCEPTION_ENTRY(_alignment_handler) + /* r4: EA of fault (set by EXCEPTION_HANDLE) */ + l.jal do_unaligned_access + l.addi r3,r1,0 /* pt_regs */ + + l.j _ret_from_exception + l.nop + +#if 0 +EXCEPTION_ENTRY(_aligment_handler) +// l.mfspr r2,r0,SPR_EEAR_BASE /* Load the efective addres */ + l.addi r2,r4,0 +// l.mfspr r5,r0,SPR_EPCR_BASE /* Load the insn address */ + l.lwz r5,PT_PC(r1) + + l.lwz r3,0(r5) /* Load insn */ + l.srli r4,r3,26 /* Shift left to get the insn opcode */ + + l.sfeqi r4,0x00 /* Check if the load/store insn is in delay slot */ + l.bf jmp + l.sfeqi r4,0x01 + l.bf jmp + l.sfeqi r4,0x03 + l.bf jmp + l.sfeqi r4,0x04 + l.bf jmp + l.sfeqi r4,0x11 + l.bf jr + l.sfeqi r4,0x12 + l.bf jr + l.nop + l.j 1f + l.addi r5,r5,4 /* Increment PC to get return insn address */ + +jmp: + l.slli r4,r3,6 /* Get the signed extended jump length */ + l.srai r4,r4,4 + + l.lwz r3,4(r5) /* Load the real load/store insn */ + + l.add r5,r5,r4 /* Calculate jump target address */ + + l.j 1f + l.srli r4,r3,26 /* Shift left to get the insn opcode */ + +jr: + l.slli r4,r3,9 /* Shift to get the reg nb */ + l.andi r4,r4,0x7c + + l.lwz r3,4(r5) /* Load the real load/store insn */ + + l.add r4,r4,r1 /* Load the jump register value from the stack */ + l.lwz r5,0(r4) + + l.srli r4,r3,26 /* Shift left to get the insn opcode */ + + +1: +// l.mtspr r0,r5,SPR_EPCR_BASE + l.sw PT_PC(r1),r5 + + l.sfeqi r4,0x26 + l.bf lhs + l.sfeqi r4,0x25 + l.bf lhz + l.sfeqi r4,0x22 + l.bf lws + l.sfeqi r4,0x21 + l.bf lwz + l.sfeqi r4,0x37 + l.bf sh + l.sfeqi r4,0x35 + l.bf sw + l.nop + +1: l.j 1b /* I don't know what to do */ + l.nop + +lhs: l.lbs r5,0(r2) + l.slli r5,r5,8 + l.lbz r6,1(r2) + l.or r5,r5,r6 + l.srli r4,r3,19 + l.andi r4,r4,0x7c + l.add r4,r4,r1 + l.j align_end + l.sw 0(r4),r5 + +lhz: l.lbz r5,0(r2) + l.slli r5,r5,8 + l.lbz r6,1(r2) + l.or r5,r5,r6 + l.srli r4,r3,19 + l.andi r4,r4,0x7c + l.add r4,r4,r1 + l.j align_end + l.sw 0(r4),r5 + +lws: l.lbs r5,0(r2) + l.slli r5,r5,24 + l.lbz r6,1(r2) + l.slli r6,r6,16 + l.or r5,r5,r6 + l.lbz r6,2(r2) + l.slli r6,r6,8 + l.or r5,r5,r6 + l.lbz r6,3(r2) + l.or r5,r5,r6 + l.srli r4,r3,19 + l.andi r4,r4,0x7c + l.add r4,r4,r1 + l.j align_end + l.sw 0(r4),r5 + +lwz: l.lbz r5,0(r2) + l.slli r5,r5,24 + l.lbz r6,1(r2) + l.slli r6,r6,16 + l.or r5,r5,r6 + l.lbz r6,2(r2) + l.slli r6,r6,8 + l.or r5,r5,r6 + l.lbz r6,3(r2) + l.or r5,r5,r6 + l.srli r4,r3,19 + l.andi r4,r4,0x7c + l.add r4,r4,r1 + l.j align_end + l.sw 0(r4),r5 + +sh: + l.srli r4,r3,9 + l.andi r4,r4,0x7c + l.add r4,r4,r1 + l.lwz r5,0(r4) + l.sb 1(r2),r5 + l.srli r5,r5,8 + l.j align_end + l.sb 0(r2),r5 + +sw: + l.srli r4,r3,9 + l.andi r4,r4,0x7c + l.add r4,r4,r1 + l.lwz r5,0(r4) + l.sb 3(r2),r5 + l.srli r5,r5,8 + l.sb 2(r2),r5 + l.srli r5,r5,8 + l.sb 1(r2),r5 + l.srli r5,r5,8 + l.j align_end + l.sb 0(r2),r5 + +align_end: + l.j _ret_from_intr + l.nop +#endif + +/* ---[ 0x700: Illegal insn exception ]---------------------------------- */ + +EXCEPTION_ENTRY(_illegal_instruction_handler) + /* r4: EA of fault (set by EXCEPTION_HANDLE) */ + l.jal do_illegal_instruction + l.addi r3,r1,0 /* pt_regs */ + + l.j _ret_from_exception + l.nop + +/* ---[ 0x800: External interrupt exception ]---------------------------- */ + +EXCEPTION_ENTRY(_external_irq_handler) +#ifdef CONFIG_OPENRISC_ESR_EXCEPTION_BUG_CHECK + l.lwz r4,PT_SR(r1) // were interrupts enabled ? + l.andi r4,r4,SPR_SR_IEE + l.sfeqi r4,0 + l.bnf 1f // ext irq enabled, all ok. + l.nop + + l.addi r1,r1,-0x8 + l.movhi r3,hi(42f) + l.ori r3,r3,lo(42f) + l.sw 0x0(r1),r3 + l.jal printk + l.sw 0x4(r1),r4 + l.addi r1,r1,0x8 + + .section .rodata, "a" +42: + .string "\n\rESR interrupt bug: in _external_irq_handler (ESR %x)\n\r" + .align 4 + .previous + + l.ori r4,r4,SPR_SR_IEE // fix the bug +// l.sw PT_SR(r1),r4 +1: +#endif + l.addi r3,r1,0 + l.movhi r8,hi(do_IRQ) + l.ori r8,r8,lo(do_IRQ) + l.jalr r8 + l.nop + l.j _ret_from_intr + l.nop + +/* ---[ 0x900: DTLB miss exception ]------------------------------------- */ + + +/* ---[ 0xa00: ITLB miss exception ]------------------------------------- */ + + +/* ---[ 0xb00: Range exception ]----------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0xb00,0xb00) + +/* ---[ 0xc00: Syscall exception ]--------------------------------------- */ + +/* + * Syscalls are a special type of exception in that they are + * _explicitly_ invoked by userspace and can therefore be + * held to conform to the same ABI as normal functions with + * respect to whether registers are preserved across the call + * or not. + */ + +/* Upon syscall entry we just save the callee-saved registers + * and not the call-clobbered ones. + */ + +_string_syscall_return: + .string "syscall return %ld \n\r\0" + .align 4 + +ENTRY(_sys_call_handler) + /* syscalls run with interrupts enabled */ + ENABLE_INTERRUPTS(r29) // enable interrupts, r29 is temp + + /* r1, EPCR, ESR a already saved */ + l.sw PT_GPR2(r1),r2 + /* r3-r8 must be saved because syscall restart relies + * on us being able to restart the syscall args... technically + * they should be clobbered, otherwise + */ + l.sw PT_GPR3(r1),r3 + /* r4 already saved */ + /* r4 holds the EEAR address of the fault, load the original r4 */ + l.lwz r4,PT_GPR4(r1) + l.sw PT_GPR5(r1),r5 + l.sw PT_GPR6(r1),r6 + l.sw PT_GPR7(r1),r7 + l.sw PT_GPR8(r1),r8 + l.sw PT_GPR9(r1),r9 + /* r10 already saved */ + l.sw PT_GPR11(r1),r11 + l.sw PT_ORIG_GPR11(r1),r11 + /* r12,r13 already saved */ + + /* r14-r28 (even) aren't touched by the syscall fast path below + * so we don't need to save them. However, the functions that return + * to userspace via a call to switch() DO need to save these because + * switch() effectively clobbers them... saving these registers for + * such functions is handled in their syscall wrappers (see fork, vfork, + * and clone, below). + + /* r30 is the only register we clobber in the fast path */ + /* r30 already saved */ +/* l.sw PT_GPR30(r1),r30 */ + /* This is used by do_signal to determine whether to check for + * syscall restart or not */ + l.sw PT_SYSCALLNO(r1),r11 + +_syscall_check_trace_enter: + /* If TIF_SYSCALL_TRACE is set, then we want to do syscall tracing */ + l.lwz r30,TI_FLAGS(r10) + l.andi r30,r30,_TIF_SYSCALL_TRACE + l.sfne r30,r0 + l.bf _syscall_trace_enter + l.nop + +_syscall_check: + /* Ensure that the syscall number is reasonable */ + l.sfgeui r11,__NR_syscalls + l.bf _syscall_badsys + l.nop + +_syscall_call: + l.movhi r29,hi(sys_call_table) + l.ori r29,r29,lo(sys_call_table) + l.slli r11,r11,2 + l.add r29,r29,r11 + l.lwz r29,0(r29) + + l.jalr r29 + l.nop + +_syscall_return: + /* All syscalls return here... just pay attention to ret_from_fork + * which does it in a round-about way. + */ + l.sw PT_GPR11(r1),r11 // save return value + +#if 0 +_syscall_debug: + l.movhi r3,hi(_string_syscall_return) + l.ori r3,r3,lo(_string_syscall_return) + l.ori r27,r0,1 + l.sw -4(r1),r27 + l.sw -8(r1),r11 + l.addi r1,r1,-8 + l.movhi r27,hi(printk) + l.ori r27,r27,lo(printk) + l.jalr r27 + l.nop + l.addi r1,r1,8 +#endif + +_syscall_check_trace_leave: + /* r30 is a callee-saved register so this should still hold the + * _TIF_SYSCALL_TRACE flag from _syscall_check_trace_enter above... + * _syscall_trace_leave expects syscall result to be in pt_regs->r11. + */ + l.sfne r30,r0 + l.bf _syscall_trace_leave + l.nop + +/* This is where the exception-return code begins... interrupts need to be + * disabled the rest of the way here because we can't afford to miss any + * interrupts that set NEED_RESCHED or SIGNALPENDING... really true? */ + +_syscall_check_work: + /* Here we need to disable interrupts */ + DISABLE_INTERRUPTS(r27,r29) + l.lwz r30,TI_FLAGS(r10) + l.andi r30,r30,_TIF_WORK_MASK + l.sfne r30,r0 + + l.bnf _syscall_resume_userspace + l.nop + + /* Work pending follows a different return path, so we need to + * make sure that all the call-saved registers get into pt_regs + * before branching... + */ + l.sw PT_GPR14(r1),r14 + l.sw PT_GPR16(r1),r16 + l.sw PT_GPR18(r1),r18 + l.sw PT_GPR20(r1),r20 + l.sw PT_GPR22(r1),r22 + l.sw PT_GPR24(r1),r24 + l.sw PT_GPR26(r1),r26 + l.sw PT_GPR28(r1),r28 + + /* _work_pending needs to be called with interrupts disabled */ + l.j _work_pending + l.nop + +_syscall_resume_userspace: +// ENABLE_INTERRUPTS(r29) + + +/* This is the hot path for returning to userspace from a syscall. If there's + * work to be done and the branch to _work_pending was taken above, then the + * return to userspace will be done via the normal exception return path... + * that path restores _all_ registers and will overwrite the "clobbered" + * registers with whatever garbage is in pt_regs -- that's OK because those + * registers are clobbered anyway and because the extra work is insignificant + * in the context of the extra work that _work_pending is doing. + +/* Once again, syscalls are special and only guarantee to preserve the + * same registers as a normal function call */ + +/* The assumption here is that the registers r14-r28 (even) are untouched and + * don't need to be restored... be sure that that's really the case! + */ + +/* This is still too much... we should only be restoring what we actually + * clobbered... we should even be using 'scratch' (odd) regs above so that + * we don't need to restore anything, hardly... + */ + + l.lwz r2,PT_GPR2(r1) + + /* Restore args */ + /* r3-r8 are technically clobbered, but syscall restart needs these + * to be restored... + */ + l.lwz r3,PT_GPR3(r1) + l.lwz r4,PT_GPR4(r1) + l.lwz r5,PT_GPR5(r1) + l.lwz r6,PT_GPR6(r1) + l.lwz r7,PT_GPR7(r1) + l.lwz r8,PT_GPR8(r1) + + l.lwz r9,PT_GPR9(r1) + l.lwz r10,PT_GPR10(r1) + l.lwz r11,PT_GPR11(r1) + + /* r30 is the only register we clobber in the fast path */ + l.lwz r30,PT_GPR30(r1) + + /* Here we use r13-r19 (odd) as scratch regs */ + l.lwz r13,PT_PC(r1) + l.lwz r15,PT_SR(r1) + l.lwz r1,PT_SP(r1) + /* Interrupts need to be disabled for setting EPCR and ESR + * so that another interrupt doesn't come in here and clobber + * them before we can use them for our l.rfe */ + DISABLE_INTERRUPTS(r17,r19) + l.mtspr r0,r13,SPR_EPCR_BASE + l.mtspr r0,r15,SPR_ESR_BASE + l.rfe + +/* End of hot path! + * Keep the below tracing and error handling out of the hot path... +*/ + +_syscall_trace_enter: + /* Here we pass pt_regs to do_syscall_trace_enter. Make sure + * that function is really getting all the info it needs as + * pt_regs isn't a complete set of userspace regs, just the + * ones relevant to the syscall... + * + * Note use of delay slot for setting argument. + */ + l.jal do_syscall_trace_enter + l.addi r3,r1,0 + + /* Restore arguments (not preserved across do_syscall_trace_enter) + * so that we can do the syscall for real and return to the syscall + * hot path. + */ + l.lwz r11,PT_SYSCALLNO(r1) + l.lwz r3,PT_GPR3(r1) + l.lwz r4,PT_GPR4(r1) + l.lwz r5,PT_GPR5(r1) + l.lwz r6,PT_GPR6(r1) + l.lwz r7,PT_GPR7(r1) + + l.j _syscall_check + l.lwz r8,PT_GPR8(r1) + +_syscall_trace_leave: + l.jal do_syscall_trace_leave + l.addi r3,r1,0 + + l.j _syscall_check_work + l.nop + +_syscall_badsys: + /* Here we effectively pretend to have executed an imaginary + * syscall that returns -ENOSYS and then return to the regular + * syscall hot path. + * Note that "return value" is set in the delay slot... + */ + l.j _syscall_return + l.addi r11,r0,-ENOSYS + +/******* END SYSCALL HANDLING *******/ + +/* ---[ 0xd00: Trap exception ]------------------------------------------ */ + +UNHANDLED_EXCEPTION(_vector_0xd00,0xd00) + +/* ---[ 0xe00: Trap exception ]------------------------------------------ */ + +EXCEPTION_ENTRY(_trap_handler) + /* r4: EA of fault (set by EXCEPTION_HANDLE) */ + l.jal do_trap + l.addi r3,r1,0 /* pt_regs */ + + l.j _ret_from_exception + l.nop + +/* ---[ 0xf00: Reserved exception ]-------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0xf00,0xf00) + +/* ---[ 0x1000: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1000,0x1000) + +/* ---[ 0x1100: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1100,0x1100) + +/* ---[ 0x1200: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1200,0x1200) + +/* ---[ 0x1300: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1300,0x1300) + +/* ---[ 0x1400: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1400,0x1400) + +/* ---[ 0x1500: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1500,0x1500) + +/* ---[ 0x1600: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1600,0x1600) + +/* ---[ 0x1700: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1700,0x1700) + +/* ---[ 0x1800: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1800,0x1800) + +/* ---[ 0x1900: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1900,0x1900) + +/* ---[ 0x1a00: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1a00,0x1a00) + +/* ---[ 0x1b00: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1b00,0x1b00) + +/* ---[ 0x1c00: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1c00,0x1c00) + +/* ---[ 0x1d00: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1d00,0x1d00) + +/* ---[ 0x1e00: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1e00,0x1e00) + +/* ---[ 0x1f00: Reserved exception ]------------------------------------- */ + +UNHANDLED_EXCEPTION(_vector_0x1f00,0x1f00) + +/* ========================================================[ return ] === */ + +_work_pending: + /* + * if (current_thread_info->flags & _TIF_NEED_RESCHED) + * schedule(); + */ + l.lwz r5,TI_FLAGS(r10) + l.andi r3,r5,_TIF_NEED_RESCHED + l.sfnei r3,0 + l.bnf _work_notifysig + l.nop + l.jal schedule + l.nop + l.j _resume_userspace + l.nop + +/* Handle pending signals and notify-resume requests. + * do_notify_resume must be passed the latest pushed pt_regs, not + * necessarily the "userspace" ones. Also, pt_regs->syscallno + * must be set so that the syscall restart functionality works. + */ +_work_notifysig: + l.jal do_notify_resume + l.ori r3,r1,0 /* pt_regs */ + +_resume_userspace: + DISABLE_INTERRUPTS(r3,r4) + l.lwz r3,TI_FLAGS(r10) + l.andi r3,r3,_TIF_WORK_MASK + l.sfnei r3,0 + l.bf _work_pending + l.nop + +_restore_all: + RESTORE_ALL + /* This returns to userspace code */ + + +ENTRY(_ret_from_intr) +ENTRY(_ret_from_exception) + l.lwz r4,PT_SR(r1) + l.andi r3,r4,SPR_SR_SM + l.sfeqi r3,0 + l.bnf _restore_all + l.nop + l.j _resume_userspace + l.nop + +ENTRY(ret_from_fork) + l.jal schedule_tail + l.nop + + /* _syscall_returns expect r11 to contain return value */ + l.lwz r11,PT_GPR11(r1) + + /* The syscall fast path return expects call-saved registers + * r12-r28 to be untouched, so we restore them here as they + * will have been effectively clobbered when arriving here + * via the call to switch() + */ + l.lwz r12,PT_GPR12(r1) + l.lwz r14,PT_GPR14(r1) + l.lwz r16,PT_GPR16(r1) + l.lwz r18,PT_GPR18(r1) + l.lwz r20,PT_GPR20(r1) + l.lwz r22,PT_GPR22(r1) + l.lwz r24,PT_GPR24(r1) + l.lwz r26,PT_GPR26(r1) + l.lwz r28,PT_GPR28(r1) + + l.j _syscall_return + l.nop + +/* Since syscalls don't save call-clobbered registers, the args to + * kernel_thread_helper will need to be passed through callee-saved + * registers and copied to the parameter registers when the thread + * begins running. + * + * See arch/openrisc/kernel/process.c: + * The args are passed as follows: + * arg1 (r3) : passed in r20 + * arg2 (r4) : passed in r22 + */ + +ENTRY(_kernel_thread_helper) + l.or r3,r20,r0 + l.or r4,r22,r0 + l.movhi r31,hi(kernel_thread_helper) + l.ori r31,r31,lo(kernel_thread_helper) + l.jr r31 + l.nop + + +/* ========================================================[ switch ] === */ + +/* + * This routine switches between two different tasks. The process + * state of one is saved on its kernel stack. Then the state + * of the other is restored from its kernel stack. The memory + * management hardware is updated to the second process's state. + * Finally, we can return to the second process, via the 'return'. + * + * Note: there are two ways to get to the "going out" portion + * of this code; either by coming in via the entry (_switch) + * or via "fork" which must set up an environment equivalent + * to the "_switch" path. If you change this (or in particular, the + * SAVE_REGS macro), you'll have to change the fork code also. + */ + + +/* _switch MUST never lay on page boundry, cause it runs from + * effective addresses and beeing interrupted by iTLB miss would kill it. + * dTLB miss seams to never accour in the bad place since data accesses + * are from task structures which are always page aligned. + * + * The problem happens in RESTORE_ALL_NO_R11 where we first set the EPCR + * register, then load the previous register values and only at the end call + * the l.rfe instruction. If get TLB miss in beetwen the EPCR register gets + * garbled and we end up calling l.rfe with the wrong EPCR. (same probably + * holds for ESR) + * + * To avoid this problems it is sufficient to align _switch to + * some nice round number smaller than it's size... + */ + +/* ABI rules apply here... we either enter _switch via schedule() or via + * an imaginary call to which we shall return at return_from_fork. Either + * way, we are a function call and only need to preserve the callee-saved + * registers when we return. As such, we don't need to save the registers + * on the stack that we won't be returning as they were... + */ + + .align 0x400 +ENTRY(_switch) + /* We don't store SR as _switch only gets called in a context where + * the SR will be the same going in and coming out... */ + + /* Set up new pt_regs struct for saving task state */ + l.addi r1,r1,-(INT_FRAME_SIZE) + + /* No need to store r1/PT_SP as it goes into KSP below */ + l.sw PT_GPR2(r1),r2 + l.sw PT_GPR9(r1),r9 + /* This is wrong, r12 shouldn't be here... but GCC is broken for the time being + * and expects r12 to be callee-saved... */ + l.sw PT_GPR12(r1),r12 + l.sw PT_GPR14(r1),r14 + l.sw PT_GPR16(r1),r16 + l.sw PT_GPR18(r1),r18 + l.sw PT_GPR20(r1),r20 + l.sw PT_GPR22(r1),r22 + l.sw PT_GPR24(r1),r24 + l.sw PT_GPR26(r1),r26 + l.sw PT_GPR28(r1),r28 + l.sw PT_GPR30(r1),r30 + + l.addi r11,r10,0 /* Save old 'current' to 'last' return value*/ + + /* We use thread_info->ksp for storing the address of the above + * structure so that we can get back to it later... we don't want + * to lose the value of thread_info->ksp, though, so store it as + * pt_regs->sp so that we can easily restore it when we are made + * live again... + */ + + /* Save the old value of thread_info->ksp as pt_regs->sp */ + l.lwz r29,TI_KSP(r10) + l.sw PT_SP(r1),r29 + + /* Swap kernel stack pointers */ + l.sw TI_KSP(r10),r1 /* Save old stack pointer */ + l.or r10,r4,r0 /* Set up new current_thread_info */ + l.lwz r1,TI_KSP(r10) /* Load new stack pointer */ + + /* Restore the old value of thread_info->ksp */ + l.lwz r29,PT_SP(r1) + l.sw TI_KSP(r10),r29 + + /* ...and restore the registers, except r11 because the return value + * has already been set above. + */ + l.lwz r2,PT_GPR2(r1) + l.lwz r9,PT_GPR9(r1) + /* No need to restore r10 */ + /* ...and do not restore r11 */ + + /* This is wrong, r12 shouldn't be here... but GCC is broken for the time being + * and expects r12 to be callee-saved... */ + l.lwz r12,PT_GPR12(r1) + l.lwz r14,PT_GPR14(r1) + l.lwz r16,PT_GPR16(r1) + l.lwz r18,PT_GPR18(r1) + l.lwz r20,PT_GPR20(r1) + l.lwz r22,PT_GPR22(r1) + l.lwz r24,PT_GPR24(r1) + l.lwz r26,PT_GPR26(r1) + l.lwz r28,PT_GPR28(r1) + l.lwz r30,PT_GPR30(r1) + + /* Unwind stack to pre-switch state */ + l.addi r1,r1,(INT_FRAME_SIZE) + + /* Return via the link-register back to where we 'came from', where that can be + * either schedule() or return_from_fork()... */ + l.jr r9 + l.nop + +/* ==================================================================== */ + +/* These all use the delay slot for setting the argument register, so the + * jump is always happening after the l.addi instruction. + * + * These are all just wrappers that don't touch the link-register r9, so the + * return from the "real" syscall function will return back to the syscall + * code that did the l.jal that brought us here. + */ + +/* fork requires that we save all the callee-saved registers because they + * are all effectively clobbered by the call to _switch. Here we store + * all the registers that aren't touched by the syscall fast path and thus + * weren't saved there. + */ + +_fork_save_extra_regs_and_call: + l.sw PT_GPR14(r1),r14 + l.sw PT_GPR16(r1),r16 + l.sw PT_GPR18(r1),r18 + l.sw PT_GPR20(r1),r20 + l.sw PT_GPR22(r1),r22 + l.sw PT_GPR24(r1),r24 + l.sw PT_GPR26(r1),r26 + l.jr r29 + l.sw PT_GPR28(r1),r28 + +ENTRY(sys_clone) + l.movhi r29,hi(_sys_clone) + l.ori r29,r29,lo(_sys_clone) + l.j _fork_save_extra_regs_and_call + l.addi r7,r1,0 + +ENTRY(sys_fork) + l.movhi r29,hi(_sys_fork) + l.ori r29,r29,lo(_sys_fork) + l.j _fork_save_extra_regs_and_call + l.addi r3,r1,0 + +ENTRY(sys_execve) + l.j _sys_execve + l.addi r6,r1,0 + +ENTRY(sys_sigaltstack) + l.j _sys_sigaltstack + l.addi r5,r1,0 + +ENTRY(sys_rt_sigreturn) + l.j _sys_rt_sigreturn + l.addi r3,r1,0 + +/* This is a catch-all syscall for atomic instructions for the OpenRISC 1000. + * The functions takes a variable number of parameters depending on which + * particular flavour of atomic you want... parameter 1 is a flag identifying + * the atomic in question. Currently, this function implements the + * following variants: + * + * XCHG: + * @flag: 1 + * @ptr1: + * @ptr2: + * Atomically exchange the values in pointers 1 and 2. + * + */ + +ENTRY(sys_or1k_atomic) + /* FIXME: This ignores r3 and always does an XCHG */ + DISABLE_INTERRUPTS(r17,r19) + l.lwz r30,0(r4) + l.lwz r28,0(r5) + l.sw 0(r4),r28 + l.sw 0(r5),r30 + ENABLE_INTERRUPTS(r17) + l.jr r9 + l.or r11,r0,r0 + +/* ============================================================[ EOF ]=== */ |