/* $Id: entry.S,v 1.37 2004/06/11 13:02:46 doyu Exp $ * * linux/arch/sh/entry.S * * Copyright (C) 1999, 2000, 2002 Niibe Yutaka * Copyright (C) 2003 Paul Mundt * * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * */ #include #include #include #include #include #include #include ! NOTE: ! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address ! to be jumped is too far, but it causes illegal slot exception. /* * entry.S contains the system-call and fault low-level handling routines. * This also contains the timer-interrupt handler, as well as all interrupts * and faults that can result in a task-switch. * * NOTE: This code handles signal-recognition, which happens every time * after a timer-interrupt and after each system call. * * NOTE: This code uses a convention that instructions in the delay slot * of a transfer-control instruction are indented by an extra space, thus: * * jmp @k0 ! control-transfer instruction * ldc k1, ssr ! delay slot * * Stack layout in 'ret_from_syscall': * ptrace needs to have all regs on the stack. * if the order here is changed, it needs to be * updated in ptrace.c and ptrace.h * * r0 * ... * r15 = stack pointer * spc * pr * ssr * gbr * mach * macl * syscall # * */ #if defined(CONFIG_KGDB_NMI) NMI_VEC = 0x1c0 ! Must catch early for debounce #endif /* Offsets to the stack */ OFF_R0 = 0 /* Return value. New ABI also arg4 */ OFF_R1 = 4 /* New ABI: arg5 */ OFF_R2 = 8 /* New ABI: arg6 */ OFF_R3 = 12 /* New ABI: syscall_nr */ OFF_R4 = 16 /* New ABI: arg0 */ OFF_R5 = 20 /* New ABI: arg1 */ OFF_R6 = 24 /* New ABI: arg2 */ OFF_R7 = 28 /* New ABI: arg3 */ OFF_SP = (15*4) OFF_PC = (16*4) OFF_SR = (16*4+8) OFF_TRA = (16*4+6*4) #define k0 r0 #define k1 r1 #define k2 r2 #define k3 r3 #define k4 r4 #define k_ex_code r2_bank /* r2_bank1 */ #define g_imask r6 /* r6_bank1 */ #define k_g_imask r6_bank /* r6_bank1 */ #define current r7 /* r7_bank1 */ /* * Kernel mode register usage: * k0 scratch * k1 scratch * k2 scratch (Exception code) * k3 scratch (Return address) * k4 scratch * k5 reserved * k6 Global Interrupt Mask (0--15 << 4) * k7 CURRENT_THREAD_INFO (pointer to current thread info) */ ! ! TLB Miss / Initial Page write exception handling ! _and_ ! TLB hits, but the access violate the protection. ! It can be valid access, such as stack grow and/or C-O-W. ! ! ! Find the pmd/pte entry and loadtlb ! If it's not found, cause address error (SEGV) ! ! Although this could be written in assembly language (and it'd be faster), ! this first version depends *much* on C implementation. ! #define CLI() \ stc sr, r0; \ or #0xf0, r0; \ ldc r0, sr #define STI() \ mov.l __INV_IMASK, r11; \ stc sr, r10; \ and r11, r10; \ stc k_g_imask, r11; \ or r11, r10; \ ldc r10, sr #if defined(CONFIG_PREEMPT) # define preempt_stop() CLI() #else # define preempt_stop() # define resume_kernel restore_all #endif #if defined(CONFIG_MMU) .align 2 ENTRY(tlb_miss_load) bra call_dpf mov #0, r5 .align 2 ENTRY(tlb_miss_store) bra call_dpf mov #1, r5 .align 2 ENTRY(initial_page_write) bra call_dpf mov #1, r5 .align 2 ENTRY(tlb_protection_violation_load) bra call_dpf mov #0, r5 .align 2 ENTRY(tlb_protection_violation_store) bra call_dpf mov #1, r5 call_dpf: mov.l 1f, r0 mov r5, r8 mov.l @r0, r6 mov r6, r9 mov.l 2f, r0 sts pr, r10 jsr @r0 mov r15, r4 ! tst r0, r0 bf/s 0f lds r10, pr rts nop 0: STI() mov.l 3f, r0 mov r9, r6 mov r8, r5 jmp @r0 mov r15, r4 .align 2 1: .long MMU_TEA 2: .long __do_page_fault 3: .long do_page_fault .align 2 ENTRY(address_error_load) bra call_dae mov #0,r5 ! writeaccess = 0 .align 2 ENTRY(address_error_store) bra call_dae mov #1,r5 ! writeaccess = 1 .align 2 call_dae: mov.l 1f, r0 mov.l @r0, r6 ! address mov.l 2f, r0 jmp @r0 mov r15, r4 ! regs .align 2 1: .long MMU_TEA 2: .long do_address_error #endif /* CONFIG_MMU */ #if defined(CONFIG_SH_STANDARD_BIOS) || defined(CONFIG_SH_KGDB) ! Handle kernel debug if either kgdb (SW) or gdb-stub (FW) is present. ! If both are configured, handle the debug traps (breakpoints) in SW, ! but still allow BIOS traps to FW. .align 2 debug_kernel: #if defined(CONFIG_SH_STANDARD_BIOS) && defined(CONFIG_SH_KGDB) /* Force BIOS call to FW (debug_trap put TRA in r8) */ mov r8,r0 shlr2 r0 cmp/eq #0x3f,r0 bt debug_kernel_fw #endif /* CONFIG_SH_STANDARD_BIOS && CONFIG_SH_KGDB */ debug_enter: #if defined(CONFIG_SH_KGDB) /* Jump to kgdb, pass stacked regs as arg */ debug_kernel_sw: mov.l 3f, r0 jmp @r0 mov r15, r4 .align 2 3: .long kgdb_handle_exception #endif /* CONFIG_SH_KGDB */ #if defined(CONFIG_SH_STANDARD_BIOS) /* Unwind the stack and jmp to the debug entry */ debug_kernel_fw: mov.l @r15+, r0 mov.l @r15+, r1 mov.l @r15+, r2 mov.l @r15+, r3 mov.l @r15+, r4 mov.l @r15+, r5 mov.l @r15+, r6 mov.l @r15+, r7 stc sr, r8 mov.l 1f, r9 ! BL =1, RB=1, IMASK=0x0F or r9, r8 ldc r8, sr ! here, change the register bank mov.l @r15+, r8 mov.l @r15+, r9 mov.l @r15+, r10 mov.l @r15+, r11 mov.l @r15+, r12 mov.l @r15+, r13 mov.l @r15+, r14 mov.l @r15+, k0 ldc.l @r15+, spc lds.l @r15+, pr mov.l @r15+, k1 ldc.l @r15+, gbr lds.l @r15+, mach lds.l @r15+, macl mov k0, r15 ! mov.l 2f, k0 mov.l @k0, k0 jmp @k0 ldc k1, ssr .align 2 1: .long 0x300000f0 2: .long gdb_vbr_vector #endif /* CONFIG_SH_STANDARD_BIOS */ #endif /* CONFIG_SH_STANDARD_BIOS || CONFIG_SH_KGDB */ .align 2 debug_trap: #if defined(CONFIG_SH_STANDARD_BIOS) || defined(CONFIG_SH_KGDB) mov #OFF_SR, r0 mov.l @(r0,r15), r0 ! get status register shll r0 shll r0 ! kernel space? bt/s debug_kernel #endif mov.l @r15, r0 ! Restore R0 value mov.l 1f, r8 jmp @r8 nop .align 2 ENTRY(exception_error) ! STI() mov.l 2f, r0 jmp @r0 nop ! .align 2 1: .long break_point_trap_software 2: .long do_exception_error .align 2 ret_from_exception: preempt_stop() ENTRY(ret_from_irq) ! mov #OFF_SR, r0 mov.l @(r0,r15), r0 ! get status register shll r0 shll r0 ! kernel space? bt/s resume_kernel ! Yes, it's from kernel, go back soon GET_THREAD_INFO(r8) #ifdef CONFIG_PREEMPT bra resume_userspace nop ENTRY(resume_kernel) mov.l @(TI_PRE_COUNT,r8), r0 ! current_thread_info->preempt_count tst r0, r0 bf noresched need_resched: mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags tst #_TIF_NEED_RESCHED, r0 ! need_resched set? bt noresched mov #OFF_SR, r0 mov.l @(r0,r15), r0 ! get status register and #0xf0, r0 ! interrupts off (exception path)? cmp/eq #0xf0, r0 bt noresched mov.l 1f, r0 mov.l r0, @(TI_PRE_COUNT,r8) STI() mov.l 2f, r0 jsr @r0 nop mov #0, r0 mov.l r0, @(TI_PRE_COUNT,r8) CLI() bra need_resched nop noresched: bra restore_all nop .align 2 1: .long PREEMPT_ACTIVE 2: .long schedule #endif ENTRY(resume_userspace) ! r8: current_thread_info CLI() mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags tst #_TIF_WORK_MASK, r0 bt/s restore_all tst #_TIF_NEED_RESCHED, r0 .align 2 work_pending: ! r0: current_thread_info->flags ! r8: current_thread_info ! t: result of "tst #_TIF_NEED_RESCHED, r0" bf/s work_resched tst #(_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK), r0 work_notifysig: bt/s restore_all mov r15, r4 mov r12, r5 ! set arg1(save_r0) mov r0, r6 mov.l 2f, r1 mova restore_all, r0 jmp @r1 lds r0, pr work_resched: #ifndef CONFIG_PREEMPT ! gUSA handling mov.l @(OFF_SP,r15), r0 ! get user space stack pointer mov r0, r1 shll r0 bf/s 1f shll r0 bf/s 1f mov #OFF_PC, r0 ! SP >= 0xc0000000 : gUSA mark mov.l @(r0,r15), r2 ! get user space PC (program counter) mov.l @(OFF_R0,r15), r3 ! end point cmp/hs r3, r2 ! r2 >= r3? bt 1f add r3, r1 ! rewind point #2 mov.l r1, @(r0,r15) ! reset PC to rewind point #2 ! 1: #endif mov.l 1f, r1 jsr @r1 ! schedule nop CLI() ! mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags tst #_TIF_WORK_MASK, r0 bt restore_all bra work_pending tst #_TIF_NEED_RESCHED, r0 .align 2 1: .long schedule 2: .long do_notify_resume .align 2 syscall_exit_work: ! r0: current_thread_info->flags ! r8: current_thread_info tst #_TIF_SYSCALL_TRACE, r0 bt/s work_pending tst #_TIF_NEED_RESCHED, r0 STI() ! XXX setup arguments... mov.l 4f, r0 ! do_syscall_trace jsr @r0 nop bra resume_userspace nop .align 2 syscall_trace_entry: ! Yes it is traced. ! XXX setup arguments... mov.l 4f, r11 ! Call do_syscall_trace which notifies jsr @r11 ! superior (will chomp R[0-7]) nop ! Reload R0-R4 from kernel stack, where the ! parent may have modified them using ! ptrace(POKEUSR). (Note that R0-R2 are ! used by the system call handler directly ! from the kernel stack anyway, so don't need ! to be reloaded here.) This allows the parent ! to rewrite system calls and args on the fly. mov.l @(OFF_R4,r15), r4 ! arg0 mov.l @(OFF_R5,r15), r5 mov.l @(OFF_R6,r15), r6 mov.l @(OFF_R7,r15), r7 ! arg3 mov.l @(OFF_R3,r15), r3 ! syscall_nr ! Arrange for do_syscall_trace to be called ! again as the system call returns. mov.l 2f, r10 ! Number of syscalls cmp/hs r10, r3 bf syscall_call mov #-ENOSYS, r0 bra syscall_exit mov.l r0, @(OFF_R0,r15) ! Return value /* * Syscall interface: * * Syscall #: R3 * Arguments #0 to #3: R4--R7 * Arguments #4 to #6: R0, R1, R2 * TRA: (number of arguments + 0x10) x 4 * * This code also handles delegating other traps to the BIOS/gdb stub * according to: * * Trap number * (TRA>>2) Purpose * -------- ------- * 0x0-0xf old syscall ABI * 0x10-0x1f new syscall ABI * 0x20-0xff delegated through debug_trap to BIOS/gdb stub. * * Note: When we're first called, the TRA value must be shifted * right 2 bits in order to get the value that was used as the "trapa" * argument. */ .align 2 .globl ret_from_fork ret_from_fork: mov.l 1f, r8 jsr @r8 mov r0, r4 bra syscall_exit nop .align 2 1: .long schedule_tail ! ENTRY(system_call) mov.l 1f, r9 mov.l @r9, r8 ! Read from TRA (Trap Address) Register ! ! Is the trap argument >= 0x20? (TRA will be >= 0x80) mov #0x7f, r9 cmp/hi r9, r8 bt/s 0f mov #OFF_TRA, r9 add r15, r9 ! mov.l r8, @r9 ! set TRA value to tra STI() ! Call the system call handler through the table. ! First check for bad syscall number mov r3, r9 mov.l 2f, r8 ! Number of syscalls cmp/hs r8, r9 bf/s good_system_call GET_THREAD_INFO(r8) syscall_badsys: ! Bad syscall number mov #-ENOSYS, r0 bra resume_userspace mov.l r0, @(OFF_R0,r15) ! Return value ! 0: bra debug_trap nop ! good_system_call: ! Good syscall number mov.l @(TI_FLAGS,r8), r8 mov #_TIF_SYSCALL_TRACE, r10 tst r10, r8 bf syscall_trace_entry ! syscall_call: shll2 r9 ! x4 mov.l 3f, r8 ! Load the address of sys_call_table add r8, r9 mov.l @r9, r8 jsr @r8 ! jump to specific syscall handler nop mov.l @(OFF_R0,r15), r12 ! save r0 mov.l r0, @(OFF_R0,r15) ! save the return value ! syscall_exit: CLI() ! GET_THREAD_INFO(r8) mov.l @(TI_FLAGS,r8), r0 ! current_thread_info->flags tst #_TIF_ALLWORK_MASK, r0 bf syscall_exit_work restore_all: mov.l @r15+, r0 mov.l @r15+, r1 mov.l @r15+, r2 mov.l @r15+, r3 mov.l @r15+, r4 mov.l @r15+, r5 mov.l @r15+, r6 mov.l @r15+, r7 ! stc sr, r8 mov.l 7f, r9 or r9, r8 ! BL =1, RB=1 ldc r8, sr ! here, change the register bank ! mov.l @r15+, r8 mov.l @r15+, r9 mov.l @r15+, r10 mov.l @r15+, r11 mov.l @r15+, r12 mov.l @r15+, r13 mov.l @r15+, r14 mov.l @r15+, k4 ! original stack pointer ldc.l @r15+, spc lds.l @r15+, pr mov.l @r15+, k3 ! original SR ldc.l @r15+, gbr lds.l @r15+, mach lds.l @r15+, macl add #4, r15 ! Skip syscall number ! #ifdef CONFIG_SH_DSP mov.l @r15+, k0 ! DSP mode marker mov.l 5f, k1 cmp/eq k0, k1 ! Do we have a DSP stack frame? bf skip_restore stc sr, k0 ! Enable CPU DSP mode or k1, k0 ! (within kernel it may be disabled) ldc k0, sr mov r2, k0 ! Backup r2 ! Restore DSP registers from stack mov r15, r2 movs.l @r2+, a1 movs.l @r2+, a0g movs.l @r2+, a1g movs.l @r2+, m0 movs.l @r2+, m1 mov r2, r15 lds.l @r15+, a0 lds.l @r15+, x0 lds.l @r15+, x1 lds.l @r15+, y0 lds.l @r15+, y1 lds.l @r15+, dsr ldc.l @r15+, rs ldc.l @r15+, re ldc.l @r15+, mod mov k0, r2 ! Restore r2 skip_restore: #endif ! ! Calculate new SR value mov k3, k2 ! original SR value mov.l 9f, k1 and k1, k2 ! Mask orignal SR value ! mov k3, k0 ! Calculate IMASK-bits shlr2 k0 and #0x3c, k0 cmp/eq #0x3c, k0 bt/s 6f shll2 k0 mov g_imask, k0 ! 6: or k0, k2 ! Set the IMASK-bits ldc k2, ssr ! #if defined(CONFIG_KGDB_NMI) ! Clear in_nmi mov.l 6f, k0 mov #0, k1 mov.b k1, @k0 #endif mov.l @r15+, k2 ! restore EXPEVT mov k4, r15 rte nop .align 2 1: .long TRA 2: .long NR_syscalls 3: .long sys_call_table 4: .long do_syscall_trace 5: .long 0x00001000 ! DSP 7: .long 0x30000000 9: __INV_IMASK: .long 0xffffff0f ! ~(IMASK) ! Exception Vector Base ! ! Should be aligned page boundary. ! .balign 4096,0,4096 ENTRY(vbr_base) .long 0 ! .balign 256,0,256 general_exception: mov.l 1f, k2 mov.l 2f, k3 bra handle_exception mov.l @k2, k2 .align 2 1: .long EXPEVT 2: .long ret_from_exception ! ! .balign 1024,0,1024 tlb_miss: mov.l 1f, k2 mov.l 4f, k3 bra handle_exception mov.l @k2, k2 ! .balign 512,0,512 interrupt: mov.l 2f, k2 mov.l 3f, k3 #if defined(CONFIG_KGDB_NMI) ! Debounce (filter nested NMI) mov.l @k2, k0 mov.l 5f, k1 cmp/eq k1, k0 bf 0f mov.l 6f, k1 tas.b @k1 bt 0f rte nop .align 2 5: .long NMI_VEC 6: .long in_nmi 0: #endif /* defined(CONFIG_KGDB_NMI) */ bra handle_exception mov.l @k2, k2 .align 2 1: .long EXPEVT 2: .long INTEVT 3: .long ret_from_irq 4: .long ret_from_exception ! ! .align 2 ENTRY(handle_exception) ! Using k0, k1 for scratch registers (r0_bank1, r1_bank), ! save all registers onto stack. ! stc ssr, k0 ! Is it from kernel space? shll k0 ! Check MD bit (bit30) by shifting it into... shll k0 ! ...the T bit bt/s 1f ! It's a kernel to kernel transition. mov r15, k0 ! save original stack to k0 /* User space to kernel */ mov #(THREAD_SIZE >> 8), k1 shll8 k1 ! k1 := THREAD_SIZE add current, k1 mov k1, r15 ! change to kernel stack ! 1: mov #-1, k4 mov.l 2f, k1 ! #ifdef CONFIG_SH_DSP mov.l r2, @-r15 ! Save r2, we need another reg stc sr, k4 mov.l 1f, r2 tst r2, k4 ! Check if in DSP mode mov.l @r15+, r2 ! Restore r2 now bt/s skip_save mov #0, k4 ! Set marker for no stack frame mov r2, k4 ! Backup r2 (in k4) for later ! Save DSP registers on stack stc.l mod, @-r15 stc.l re, @-r15 stc.l rs, @-r15 sts.l dsr, @-r15 sts.l y1, @-r15 sts.l y0, @-r15 sts.l x1, @-r15 sts.l x0, @-r15 sts.l a0, @-r15 ! GAS is broken, does not generate correct "movs.l Ds,@-As" instr. ! FIXME: Make sure that this is still the case with newer toolchains, ! as we're not at all interested in supporting ancient toolchains at ! this point. -- PFM. mov r15, r2 .word 0xf653 ! movs.l a1, @-r2 .word 0xf6f3 ! movs.l a0g, @-r2 .word 0xf6d3 ! movs.l a1g, @-r2 .word 0xf6c3 ! movs.l m0, @-r2 .word 0xf6e3 ! movs.l m1, @-r2 mov r2, r15 mov k4, r2 ! Restore r2 mov.l 1f, k4 ! Force DSP stack frame skip_save: mov.l k4, @-r15 ! Push DSP mode marker onto stack #endif ! Save the user registers on the stack. mov.l k2, @-r15 ! EXPEVT mov.l k4, @-r15 ! set TRA (default: -1) ! sts.l macl, @-r15 sts.l mach, @-r15 stc.l gbr, @-r15 stc.l ssr, @-r15 sts.l pr, @-r15 stc.l spc, @-r15 ! lds k3, pr ! Set the return address to pr ! mov.l k0, @-r15 ! save orignal stack mov.l r14, @-r15 mov.l r13, @-r15 mov.l r12, @-r15 mov.l r11, @-r15 mov.l r10, @-r15 mov.l r9, @-r15 mov.l r8, @-r15 ! stc sr, r8 ! Back to normal register bank, and or k1, r8 ! Block all interrupts mov.l 3f, k1 and k1, r8 ! ... ldc r8, sr ! ...changed here. ! mov.l r7, @-r15 mov.l r6, @-r15 mov.l r5, @-r15 mov.l r4, @-r15 mov.l r3, @-r15 mov.l r2, @-r15 mov.l r1, @-r15 mov.l r0, @-r15 ! Then, dispatch to the handler, according to the exception code. stc k_ex_code, r8 shlr2 r8 shlr r8 mov.l 4f, r9 add r8, r9 mov.l @r9, r9 jmp @r9 nop .align 2 1: .long 0x00001000 ! DSP=1 2: .long 0x000080f0 ! FD=1, IMASK=15 3: .long 0xcfffffff ! RB=0, BL=0 4: .long exception_handling_table .align 2 ENTRY(exception_none) rts nop