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Message-ID: <51062C5F.90003@synopsys.com>
Date: Mon, 28 Jan 2013 13:14:31 +0530
From: Vineet Gupta <Vineet.Gupta1@...opsys.com>
To: Al Viro <viro@...IV.linux.org.uk>
CC: <linux-arch@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<arnd@...db.de>
Subject: Re: [PATCH v3 14/71] ARC: Low level IRQ/Trap/Exception Handling
Hi Al,
On Thursday 24 January 2013 04:35 PM, Vineet Gupta wrote:
> Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
> Cc: Al Viro <viro@...IV.linux.org.uk>
> ---
> arch/arc/include/asm/entry.h | 495 ++++++++++++++++++++++++++++++++++++
> arch/arc/kernel/entry.S | 571 ++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 1066 insertions(+), 0 deletions(-)
> create mode 100644 arch/arc/include/asm/entry.h
> create mode 100644 arch/arc/kernel/entry.S
>
> diff --git a/arch/arc/include/asm/entry.h b/arch/arc/include/asm/entry.h
> new file mode 100644
> index 0000000..63705b1
> --- /dev/null
> +++ b/arch/arc/include/asm/entry.h
> @@ -0,0 +1,495 @@
> +/*
> + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * Vineetg: Aug 28th 2008: Bug #94984
> + * -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap
> + * Normally CPU does this automatically, however when doing FAKE rtie,
> + * we also need to explicitly do this. The problem in macros
> + * FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit
> + * was being "CLEARED" rather then "SET". Actually "SET" clears ZOL context
> + *
> + * Vineetg: May 5th 2008
> + * - Defined Stack Switching Macro to be reused in all intr/excp hdlrs
> + * - Shaved off 11 instructions from RESTORE_ALL_INT1 by using the
> + * address Write back load ld.ab instead of seperate ld/add instn
> + *
> + * Amit Bhor, Sameer Dhavale: Codito Technologies 2004
> + */
> +
> +#ifndef __ASM_ARC_ENTRY_H
> +#define __ASM_ARC_ENTRY_H
> +
> +#ifdef __ASSEMBLY__
> +#include <asm/unistd.h> /* For NR_syscalls defination */
> +#include <asm/asm-offsets.h>
> +#include <asm/arcregs.h>
> +#include <asm/ptrace.h>
> +#include <asm/thread_info.h> /* For THREAD_SIZE */
> +
> +/* Note on the LD/ST addr modes with addr reg wback
> + *
> + * LD.a same as LD.aw
> + *
> + * LD.a reg1, [reg2, x] => Pre Incr
> + * Eff Addr for load = [reg2 + x]
> + *
> + * LD.ab reg1, [reg2, x] => Post Incr
> + * Eff Addr for load = [reg2]
> + */
> +
> +/*--------------------------------------------------------------
> + * Save caller saved registers (scratch registers) ( r0 - r12 )
> + * Registers are pushed / popped in the order defined in struct ptregs
> + * in asm/ptrace.h
> + *-------------------------------------------------------------*/
> +.macro SAVE_CALLER_SAVED
> + st.a r0, [sp, -4]
> + st.a r1, [sp, -4]
> + st.a r2, [sp, -4]
> + st.a r3, [sp, -4]
> + st.a r4, [sp, -4]
> + st.a r5, [sp, -4]
> + st.a r6, [sp, -4]
> + st.a r7, [sp, -4]
> + st.a r8, [sp, -4]
> + st.a r9, [sp, -4]
> + st.a r10, [sp, -4]
> + st.a r11, [sp, -4]
> + st.a r12, [sp, -4]
> +.endm
> +
> +/*--------------------------------------------------------------
> + * Restore caller saved registers (scratch registers)
> + *-------------------------------------------------------------*/
> +.macro RESTORE_CALLER_SAVED
> + ld.ab r12, [sp, 4]
> + ld.ab r11, [sp, 4]
> + ld.ab r10, [sp, 4]
> + ld.ab r9, [sp, 4]
> + ld.ab r8, [sp, 4]
> + ld.ab r7, [sp, 4]
> + ld.ab r6, [sp, 4]
> + ld.ab r5, [sp, 4]
> + ld.ab r4, [sp, 4]
> + ld.ab r3, [sp, 4]
> + ld.ab r2, [sp, 4]
> + ld.ab r1, [sp, 4]
> + ld.ab r0, [sp, 4]
> +.endm
> +
> +
> +/*--------------------------------------------------------------
> + * Save callee saved registers (non scratch registers) ( r13 - r25 )
> + * on kernel stack.
> + * User mode callee regs need to be saved in case of
> + * -fork and friends for replicating from parent to child
> + * -before going into do_signal( ) for ptrace/core-dump
> + * Special case handling is required for r25 in case it is used by kernel
> + * for caching task ptr. Low level exception/ISR save user mode r25
> + * into task->thread.user_r25. So it needs to be retrieved from there and
> + * saved into kernel stack with rest of callee reg-file
> + *-------------------------------------------------------------*/
> +.macro SAVE_CALLEE_SAVED_USER
> + st.a r13, [sp, -4]
> + st.a r14, [sp, -4]
> + st.a r15, [sp, -4]
> + st.a r16, [sp, -4]
> + st.a r17, [sp, -4]
> + st.a r18, [sp, -4]
> + st.a r19, [sp, -4]
> + st.a r20, [sp, -4]
> + st.a r21, [sp, -4]
> + st.a r22, [sp, -4]
> + st.a r23, [sp, -4]
> + st.a r24, [sp, -4]
> + st.a r25, [sp, -4]
> +
> + /* move up by 1 word to "create" callee_regs->"stack_place_holder" */
> + sub sp, sp, 4
> +.endm
> +
> +/*--------------------------------------------------------------
> + * Save callee saved registers (non scratch registers) ( r13 - r25 )
> + * kernel mode callee regs needed to be saved in case of context switch
> + * If r25 is used for caching task pointer then that need not be saved
> + * as it can be re-created from current task global
> + *-------------------------------------------------------------*/
> +.macro SAVE_CALLEE_SAVED_KERNEL
> + st.a r13, [sp, -4]
> + st.a r14, [sp, -4]
> + st.a r15, [sp, -4]
> + st.a r16, [sp, -4]
> + st.a r17, [sp, -4]
> + st.a r18, [sp, -4]
> + st.a r19, [sp, -4]
> + st.a r20, [sp, -4]
> + st.a r21, [sp, -4]
> + st.a r22, [sp, -4]
> + st.a r23, [sp, -4]
> + st.a r24, [sp, -4]
> + st.a r25, [sp, -4]
> + sub sp, sp, 4
> +.endm
> +
> +/*--------------------------------------------------------------
> + * RESTORE_CALLEE_SAVED_KERNEL:
> + * Loads callee (non scratch) Reg File by popping from Kernel mode stack.
> + * This is reverse of SAVE_CALLEE_SAVED,
> + *
> + * NOTE:
> + * Ideally this shd only be called in switch_to for loading
> + * switched-IN task's CALLEE Reg File.
> + * For all other cases RESTORE_CALLEE_SAVED_FAST must be used
> + * which simply pops the stack w/o touching regs.
> + *-------------------------------------------------------------*/
> +.macro RESTORE_CALLEE_SAVED_KERNEL
> +
> + add sp, sp, 4 /* skip "callee_regs->stack_place_holder" */
> + ld.ab r25, [sp, 4]
> + ld.ab r24, [sp, 4]
> + ld.ab r23, [sp, 4]
> + ld.ab r22, [sp, 4]
> + ld.ab r21, [sp, 4]
> + ld.ab r20, [sp, 4]
> + ld.ab r19, [sp, 4]
> + ld.ab r18, [sp, 4]
> + ld.ab r17, [sp, 4]
> + ld.ab r16, [sp, 4]
> + ld.ab r15, [sp, 4]
> + ld.ab r14, [sp, 4]
> + ld.ab r13, [sp, 4]
> +
> +.endm
> +
> +/*--------------------------------------------------------------
> + * Super FAST Restore callee saved regs by simply re-adjusting SP
> + *-------------------------------------------------------------*/
> +.macro DISCARD_CALLEE_SAVED_USER
> + add sp, sp, 14 * 4
> +.endm
> +
> +/*--------------------------------------------------------------
> + * Restore User mode r25 saved in task_struct->thread.user_r25
> + *-------------------------------------------------------------*/
> +.macro RESTORE_USER_R25
> + ld r25, [r25, TASK_THREAD + THREAD_USER_R25]
> +.endm
> +
> +/*-------------------------------------------------------------
> + * given a tsk struct, get to the base of it's kernel mode stack
> + * tsk->thread_info is really a PAGE, whose bottom hoists stack
> + * which grows upwards towards thread_info
> + *------------------------------------------------------------*/
> +
> +.macro GET_TSK_STACK_BASE tsk, out
> +
> + /* Get task->thread_info (this is essentially start of a PAGE) */
> + ld \out, [\tsk, TASK_THREAD_INFO]
> +
> + /* Go to end of page where stack begins (grows upwards) */
> + add2 \out, \out, (THREAD_SIZE - 4)/4 /* one word GUTTER */
> +
> +.endm
> +
> +/*--------------------------------------------------------------
> + * Switch to Kernel Mode stack if SP points to User Mode stack
> + *
> + * Entry : r9 contains pre-IRQ/exception/trap status32
> + * Exit : SP is set to kernel mode stack pointer
> + * Clobbers: r9
> + *-------------------------------------------------------------*/
> +
> +.macro SWITCH_TO_KERNEL_STK
> +
> + /* User Mode when this happened ? Yes: Proceed to switch stack */
> + bbit1 r9, STATUS_U_BIT, 88f
> +
> + /* OK we were already in kernel mode when this event happened, thus can
> + * assume SP is kernel mode SP. _NO_ need to do any stack switching
> + */
> +
> + /* Save Pre Intr/Exception KERNEL MODE SP on kernel stack
> + * safe-keeping not really needed, but it keeps the epilogue code
> + * (SP restore) simpler/uniform.
> + */
> + b.d 77f
> +
> + st.a sp, [sp, -12] ; Make room for orig_r0 and orig_r8
> +
> +88: /*------Intr/Ecxp happened in user mode, "switch" stack ------ */
> +
> + GET_CURR_TASK_ON_CPU r9
> +
> + /* With current tsk in r9, get it's kernel mode stack base */
> + GET_TSK_STACK_BASE r9, r9
> +
> +#ifdef PT_REGS_CANARY
> + st 0xabcdabcd, [r9, 0]
> +#endif
> +
> + /* Save Pre Intr/Exception User SP on kernel stack */
> + st.a sp, [r9, -12] ; Make room for orig_r0 and orig_r8
> +
> + /* CAUTION:
> + * SP should be set at the very end when we are done with everything
> + * In case of 2 levels of interrupt we depend on value of SP to assume
> + * that everything else is done (loading r25 etc)
> + */
> +
> + /* set SP to point to kernel mode stack */
> + mov sp, r9
> +
> +77: /* ----- Stack Switched to kernel Mode, Now save REG FILE ----- */
> +
> +.endm
> +
> +/*------------------------------------------------------------
> + * "FAKE" a rtie to return from CPU Exception context
> + * This is to re-enable Exceptions within exception
> + * Look at EV_ProtV to see how this is actually used
> + *-------------------------------------------------------------*/
> +
> +.macro FAKE_RET_FROM_EXCPN reg
> +
> + ld \reg, [sp, PT_status32]
> + bic \reg, \reg, (STATUS_U_MASK|STATUS_DE_MASK)
> + bset \reg, \reg, STATUS_L_BIT
> + sr \reg, [erstatus]
> + mov \reg, 55f
> + sr \reg, [eret]
> +
> + rtie
> +55:
> +.endm
> +
> +/*
> + * @reg [OUT] &thread_info of "current"
> + */
> +.macro GET_CURR_THR_INFO_FROM_SP reg
> + and \reg, sp, ~(THREAD_SIZE - 1)
> +.endm
> +
> +/*
> + * @reg [OUT] thread_info->flags of "current"
> + */
> +.macro GET_CURR_THR_INFO_FLAGS reg
> + GET_CURR_THR_INFO_FROM_SP \reg
> + ld \reg, [\reg, THREAD_INFO_FLAGS]
> +.endm
> +
> +/*--------------------------------------------------------------
> + * For early Exception Prologue, a core reg is temporarily needed to
> + * code the rest of prolog (stack switching). This is done by stashing
> + * it to memory (non-SMP case) or SCRATCH0 Aux Reg (SMP).
> + *
> + * Before saving the full regfile - this reg is restored back, only
> + * to be saved again on kernel mode stack, as part of ptregs.
> + *-------------------------------------------------------------*/
> +.macro EXCPN_PROLOG_FREEUP_REG reg
> + st \reg, [@ex_saved_reg1]
> +.endm
> +
> +.macro EXCPN_PROLOG_RESTORE_REG reg
> + ld \reg, [@ex_saved_reg1]
> +.endm
> +
> +/*--------------------------------------------------------------
> + * Save all registers used by Exceptions (TLB Miss, Prot-V, Mem err etc)
> + * Requires SP to be already switched to kernel mode Stack
> + * sp points to the next free element on the stack at exit of this macro.
> + * Registers are pushed / popped in the order defined in struct ptregs
> + * in asm/ptrace.h
> + * Note that syscalls are implemented via TRAP which is also a exception
> + * from CPU's point of view
> + *-------------------------------------------------------------*/
> +.macro SAVE_ALL_EXCEPTION marker
> +
> + /* Restore r9 used to code the early prologue */
> + EXCPN_PROLOG_RESTORE_REG r9
> +
> + /* Save the complete regfile now */
> +
> + /* orig_r8 marker:
> + * syscalls -> 1 to NR_SYSCALLS
> + * Exceptions -> NR_SYSCALLS + 1
> + * Break-point-> NR_SYSCALLS + 2
> + */
> + st \marker, [sp, 8]
> + st r0, [sp, 4] /* orig_r0, needed only for sys calls */
> + SAVE_CALLER_SAVED
> + st.a r26, [sp, -4] /* gp */
> + st.a fp, [sp, -4]
> + st.a blink, [sp, -4]
> + lr r9, [eret]
> + st.a r9, [sp, -4]
> + lr r9, [erstatus]
> + st.a r9, [sp, -4]
> + st.a lp_count, [sp, -4]
> + lr r9, [lp_end]
> + st.a r9, [sp, -4]
> + lr r9, [lp_start]
> + st.a r9, [sp, -4]
> + lr r9, [erbta]
> + st.a r9, [sp, -4]
> +
> +#ifdef PT_REGS_CANARY
> + mov r9, 0xdeadbeef
> + st r9, [sp, -4]
> +#endif
> +
> + /* move up by 1 word to "create" pt_regs->"stack_place_holder" */
> + sub sp, sp, 4
> +.endm
> +
> +/*--------------------------------------------------------------
> + * Save scratch regs for exceptions
> + *-------------------------------------------------------------*/
> +.macro SAVE_ALL_SYS
> + SAVE_ALL_EXCEPTION (NR_syscalls + 1)
> +.endm
> +
> +/*--------------------------------------------------------------
> + * Save scratch regs for sys calls
> + *-------------------------------------------------------------*/
> +.macro SAVE_ALL_TRAP
> + SAVE_ALL_EXCEPTION r8
> +.endm
> +
> +/*--------------------------------------------------------------
> + * Restore all registers used by system call or Exceptions
> + * SP should always be pointing to the next free stack element
> + * when entering this macro.
> + *
> + * NOTE:
> + *
> + * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg
> + * for memory load operations. If used in that way interrupts are deffered
> + * by hardware and that is not good.
> + *-------------------------------------------------------------*/
> +.macro RESTORE_ALL_SYS
> +
> + add sp, sp, 4 /* hop over unused "pt_regs->stack_place_holder" */
> +
> + ld.ab r9, [sp, 4]
> + sr r9, [erbta]
> + ld.ab r9, [sp, 4]
> + sr r9, [lp_start]
> + ld.ab r9, [sp, 4]
> + sr r9, [lp_end]
> + ld.ab r9, [sp, 4]
> + mov lp_count, r9
> + ld.ab r9, [sp, 4]
> + sr r9, [erstatus]
> + ld.ab r9, [sp, 4]
> + sr r9, [eret]
> + ld.ab blink, [sp, 4]
> + ld.ab fp, [sp, 4]
> + ld.ab r26, [sp, 4] /* gp */
> + RESTORE_CALLER_SAVED
> +
> + ld sp, [sp] /* restore original sp */
> + /* orig_r0 and orig_r8 skipped automatically */
> +.endm
> +
> +
> +/*--------------------------------------------------------------
> + * Save all registers used by interrupt handlers.
> + *-------------------------------------------------------------*/
> +.macro SAVE_ALL_INT1
> +
> + /* restore original r9 , saved in int1_saved_reg
> + * It will be saved on stack in macro: SAVE_CALLER_SAVED
> + */
> + ld r9, [@int1_saved_reg]
> +
> + /* now we are ready to save the remaining context :) */
> + st -1, [sp, 8] /* orig_r8, -1 for interuppt level one */
> + st 0, [sp, 4] /* orig_r0 , N/A for IRQ */
> + SAVE_CALLER_SAVED
> + st.a r26, [sp, -4] /* gp */
> + st.a fp, [sp, -4]
> + st.a blink, [sp, -4]
> + st.a ilink1, [sp, -4]
> + lr r9, [status32_l1]
> + st.a r9, [sp, -4]
> + st.a lp_count, [sp, -4]
> + lr r9, [lp_end]
> + st.a r9, [sp, -4]
> + lr r9, [lp_start]
> + st.a r9, [sp, -4]
> + lr r9, [bta_l1]
> + st.a r9, [sp, -4]
> +
> +#ifdef PT_REGS_CANARY
> + mov r9, 0xdeadbee1
> + st r9, [sp, -4]
> +#endif
> + /* move up by 1 word to "create" pt_regs->"stack_place_holder" */
> + sub sp, sp, 4
> +.endm
> +
> +/*--------------------------------------------------------------
> + * Restore all registers used by interrupt handlers.
> + *
> + * NOTE:
> + *
> + * It is recommended that lp_count/ilink1/ilink2 not be used as a dest reg
> + * for memory load operations. If used in that way interrupts are deffered
> + * by hardware and that is not good.
> + *-------------------------------------------------------------*/
> +
> +.macro RESTORE_ALL_INT1
> + add sp, sp, 4 /* hop over unused "pt_regs->stack_place_holder" */
> +
> + ld.ab r9, [sp, 4] /* Actual reg file */
> + sr r9, [bta_l1]
> + ld.ab r9, [sp, 4]
> + sr r9, [lp_start]
> + ld.ab r9, [sp, 4]
> + sr r9, [lp_end]
> + ld.ab r9, [sp, 4]
> + mov lp_count, r9
> + ld.ab r9, [sp, 4]
> + sr r9, [status32_l1]
> + ld.ab r9, [sp, 4]
> + mov ilink1, r9
> + ld.ab blink, [sp, 4]
> + ld.ab fp, [sp, 4]
> + ld.ab r26, [sp, 4] /* gp */
> + RESTORE_CALLER_SAVED
> +
> + ld sp, [sp] /* restore original sp */
> + /* orig_r0 and orig_r8 skipped automatically */
> +.endm
> +
> +/* Get CPU-ID of this core */
> +.macro GET_CPU_ID reg
> + lr \reg, [identity]
> + lsr \reg, \reg, 8
> + bmsk \reg, \reg, 7
> +.endm
> +
> +.macro GET_CURR_TASK_ON_CPU reg
> + ld \reg, [@_current_task]
> +.endm
> +
> +.macro SET_CURR_TASK_ON_CPU tsk, tmp
> + st \tsk, [@_current_task]
> +.endm
> +
> +/* ------------------------------------------------------------------
> + * Get the ptr to some field of Current Task at @off in task struct
> + */
> +
> +.macro GET_CURR_TASK_FIELD_PTR off, reg
> + GET_CURR_TASK_ON_CPU \reg
> + add \reg, \reg, \off
> +.endm
> +
> +#endif /* __ASSEMBLY__ */
> +
> +#endif /* __ASM_ARC_ENTRY_H */
> diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
> new file mode 100644
> index 0000000..a4acc9e
> --- /dev/null
> +++ b/arch/arc/kernel/entry.S
> @@ -0,0 +1,571 @@
> +/*
> + * Low Level Interrupts/Traps/Exceptions(non-TLB) Handling for ARC
> + *
> + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * vineetg: Nov 2010:
> + * -Vector table jumps (@8 bytes) converted into branches (@4 bytes)
> + * -To maintain the slot size of 8 bytes/vector, added nop, which is
> + * not executed at runtime.
> + *
> + * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK)
> + * -do_signal()invoked upon TIF_RESTORE_SIGMASK as well
> + * -Wrappers for sys_{,rt_}sigsuspend() nolonger needed as they don't
> + * need ptregs anymore
> + *
> + * Vineetg: Oct 2009
> + * -In a rare scenario, Process gets a Priv-V exception and gets scheduled
> + * out. Since we don't do FAKE RTIE for Priv-V, CPU excpetion state remains
> + * active (AE bit enabled). This causes a double fault for a subseq valid
> + * exception. Thus FAKE RTIE needed in low level Priv-Violation handler.
> + * Instr Error could also cause similar scenario, so same there as well.
> + *
> + * Vineetg: Aug 28th 2008: Bug #94984
> + * -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap
> + * Normally CPU does this automatically, however when doing FAKE rtie,
> + * we need to explicitly do this. The problem in macros
> + * FAKE_RET_FROM_EXCPN and FAKE_RET_FROM_EXCPN_LOCK_IRQ was that this bit
> + * was being "CLEARED" rather then "SET". Since it is Loop INHIBIT Bit,
> + * setting it and not clearing it clears ZOL context
> + *
> + * Vineetg: Dec 22, 2007
> + * Minor Surgery of Low Level ISR to make it SMP safe
> + * - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR
> + * - _current_task is made an array of NR_CPUS
> + * - Access of _current_task wrapped inside a macro so that if hardware
> + * team agrees for a dedicated reg, no other code is touched
> + *
> + * Amit Bhor, Rahul Trivedi, Kanika Nema, Sameer Dhavale : Codito Tech 2004
> + */
> +
> +/*------------------------------------------------------------------
> + * Function ABI
> + *------------------------------------------------------------------
> + *
> + * Arguments r0 - r7
> + * Caller Saved Registers r0 - r12
> + * Callee Saved Registers r13- r25
> + * Global Pointer (gp) r26
> + * Frame Pointer (fp) r27
> + * Stack Pointer (sp) r28
> + * Interrupt link register (ilink1) r29
> + * Interrupt link register (ilink2) r30
> + * Branch link register (blink) r31
> + *------------------------------------------------------------------
> + */
> +
> + .cpu A7
> +
> +;############################ Vector Table #################################
> +
> +.macro VECTOR lbl
> +#if 1 /* Just in case, build breaks */
> + j \lbl
> +#else
> + b \lbl
> + nop
> +#endif
> +.endm
> +
> + .section .vector, "ax",@progbits
> + .align 4
> +
> +/* Each entry in the vector table must occupy 2 words. Since it is a jump
> + * across sections (.vector to .text) we are gauranteed that 'j somewhere'
> + * will use the 'j limm' form of the intrsuction as long as somewhere is in
> + * a section other than .vector.
> + */
> +
> +; ********* Critical System Events **********************
> +VECTOR res_service ; 0x0, Restart Vector (0x0)
> +VECTOR mem_service ; 0x8, Mem exception (0x1)
> +VECTOR instr_service ; 0x10, Instrn Error (0x2)
> +
> +; ******************** Device ISRs **********************
> +VECTOR handle_interrupt_level1
> +
> +VECTOR handle_interrupt_level1
> +
> +VECTOR handle_interrupt_level1
> +
> +VECTOR handle_interrupt_level1
> +
> +.rept 25
> +VECTOR handle_interrupt_level1 ; Other devices
> +.endr
> +
> +/* FOR ARC600: timer = 0x3, uart = 0x8, emac = 0x10 */
> +
> +; ******************** Exceptions **********************
> +VECTOR EV_MachineCheck ; 0x100, Fatal Machine check (0x20)
> +VECTOR EV_TLBMissI ; 0x108, Intruction TLB miss (0x21)
> +VECTOR EV_TLBMissD ; 0x110, Data TLB miss (0x22)
> +VECTOR EV_TLBProtV ; 0x118, Protection Violation (0x23)
> + ; or Misaligned Access
> +VECTOR EV_PrivilegeV ; 0x120, Privilege Violation (0x24)
> +VECTOR EV_Trap ; 0x128, Trap exception (0x25)
> +VECTOR EV_Extension ; 0x130, Extn Intruction Excp (0x26)
> +
> +.rept 24
> +VECTOR reserved ; Reserved Exceptions
> +.endr
> +
> +#include <linux/linkage.h> /* ARC_{EXTRY,EXIT} */
> +#include <asm/entry.h> /* SAVE_ALL_{INT1,INT2,TRAP...} */
> +#include <asm/errno.h>
> +#include <asm/arcregs.h>
> +#include <asm/irqflags.h>
> +
> +;##################### Scratch Mem for IRQ stack switching #############
> +
> + .section .data ; NOT .global
> + .align 32
> + .type int1_saved_reg, @object
> + .size int1_saved_reg, 4
> +int1_saved_reg:
> + .zero 4
> +
> +; ---------------------------------------------
> + .section .text, "ax",@progbits
> +
> +res_service: ; processor restart
> + flag 0x1 ; not implemented
> + nop
> + nop
> +
> +reserved: ; processor restart
> + rtie ; jump to processor initializations
> +
> +;##################### Interrupt Handling ##############################
> +
> +; ---------------------------------------------
> +; Level 1 ISR
> +; ---------------------------------------------
> +ARC_ENTRY handle_interrupt_level1
> +
> + /* free up r9 as scratchpad */
> + st r9, [@int1_saved_reg]
> +
> + ;Which mode (user/kernel) was the system in when intr occured
> + lr r9, [status32_l1]
> +
> + SWITCH_TO_KERNEL_STK
> + SAVE_ALL_INT1
> +
> + lr r0, [icause1]
> + and r0, r0, 0x1f
> +
> + bl.d @arch_do_IRQ
> + mov r1, sp
> +
> + mov r8,0x1
> + sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg
> +
> + b ret_from_exception
> +ARC_EXIT handle_interrupt_level1
> +
> +;################### Non TLB Exception Handling #############################
> +
> +; ---------------------------------------------
> +; Instruction Error Exception Handler
> +; ---------------------------------------------
> +
> +ARC_ENTRY instr_service
> +
> + EXCPN_PROLOG_FREEUP_REG r9
> +
> + lr r9, [erstatus]
> +
> + SWITCH_TO_KERNEL_STK
> + SAVE_ALL_SYS
> +
> + lr r0, [ecr]
> + lr r1, [efa]
> +
> + mov r2, sp
> +
> + FAKE_RET_FROM_EXCPN r9
> +
> + bl do_insterror_or_kprobe
> + b ret_from_exception
> +ARC_EXIT instr_service
> +
> +; ---------------------------------------------
> +; Memory Error Exception Handler
> +; ---------------------------------------------
> +
> +ARC_ENTRY mem_service
> +
> + EXCPN_PROLOG_FREEUP_REG r9
> +
> + lr r9, [erstatus]
> +
> + SWITCH_TO_KERNEL_STK
> + SAVE_ALL_SYS
> +
> + lr r0, [ecr]
> + lr r1, [efa]
> + mov r2, sp
> + bl do_memory_error
> + b ret_from_exception
> +ARC_EXIT mem_service
> +
> +; ---------------------------------------------
> +; Machine Check Exception Handler
> +; ---------------------------------------------
> +
> +ARC_ENTRY EV_MachineCheck
> +
> + EXCPN_PROLOG_FREEUP_REG r9
> + lr r9, [erstatus]
> +
> + SWITCH_TO_KERNEL_STK
> + SAVE_ALL_SYS
> +
> + lr r0, [ecr]
> + lr r1, [efa]
> + mov r2, sp
> +
> + brne r0, 0x200100, 1f
> + bl do_tlb_overlap_fault
> + b ret_from_exception
> +
> +1:
> + ; DEAD END: can't do much, display Regs and HALT
> + SAVE_CALLEE_SAVED_USER
> +
> + GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10
> + st sp, [r10, THREAD_CALLEE_REG]
> +
> + j do_machine_check_fault
> +
> +ARC_EXIT EV_MachineCheck
> +
> +; ---------------------------------------------
> +; Protection Violation Exception Handler
> +; ---------------------------------------------
> +
> +ARC_ENTRY EV_TLBProtV
> +
> + EXCPN_PROLOG_FREEUP_REG r9
> +
> + ;Which mode (user/kernel) was the system in when Exception occured
> + lr r9, [erstatus]
> +
> + SWITCH_TO_KERNEL_STK
> + SAVE_ALL_SYS
> +
> + ;---------(3) Save some more regs-----------------
> + ; vineetg: Mar 6th: Random Seg Fault issue #1
> + ; ecr and efa were not saved in case an Intr sneaks in
> + ; after fake rtie
> + ;
> + lr r3, [ecr]
> + lr r4, [efa]
> +
> + ; --------(4) Return from CPU Exception Mode ---------
> + ; Fake a rtie, but rtie to next label
> + ; That way, subsequently, do_page_fault ( ) executes in pure kernel
> + ; mode with further Exceptions enabled
> +
> + FAKE_RET_FROM_EXCPN r9
> +
> + ;------ (5) Type of Protection Violation? ----------
> + ;
> + ; ProtV Hardware Exception is triggered for Access Faults of 2 types
> + ; -Access Violaton (WRITE to READ ONLY Page) - for linux COW
> + ; -Unaligned Access (READ/WRITE on odd boundary)
> + ;
> + cmp r3, 0x230400 ; Misaligned data access ?
> + beq 4f
> +
> + ;========= (6a) Access Violation Processing ========
> + cmp r3, 0x230100
> + mov r1, 0x0 ; if LD exception ? write = 0
> + mov.ne r1, 0x1 ; else write = 1
> +
> + mov r2, r4 ; faulting address
> + mov r0, sp ; pt_regs
> + bl do_page_fault
> + b ret_from_exception
> +
> + ;========== (6b) Non aligned access ============
> +4:
> + mov r0, r3 ; cause code
> + mov r1, r4 ; faulting address
> + mov r2, sp ; pt_regs
> +
> + bl do_misaligned_access
> + b ret_from_exception
> +
> +ARC_EXIT EV_TLBProtV
> +
> +; ---------------------------------------------
> +; Privilege Violation Exception Handler
> +; ---------------------------------------------
> +ARC_ENTRY EV_PrivilegeV
> +
> + EXCPN_PROLOG_FREEUP_REG r9
> +
> + lr r9, [erstatus]
> +
> + SWITCH_TO_KERNEL_STK
> + SAVE_ALL_SYS
> +
> + lr r0, [ecr]
> + lr r1, [efa]
> + mov r2, sp
> +
> + FAKE_RET_FROM_EXCPN r9
> +
> + bl do_privilege_fault
> + b ret_from_exception
> +ARC_EXIT EV_PrivilegeV
> +
> +; ---------------------------------------------
> +; Extension Instruction Exception Handler
> +; ---------------------------------------------
> +ARC_ENTRY EV_Extension
> +
> + EXCPN_PROLOG_FREEUP_REG r9
> + lr r9, [erstatus]
> +
> + SWITCH_TO_KERNEL_STK
> + SAVE_ALL_SYS
> +
> + lr r0, [ecr]
> + lr r1, [efa]
> + mov r2, sp
> + bl do_extension_fault
> + b ret_from_exception
> +ARC_EXIT EV_Extension
> +
> +;################### Break Point TRAP ##########################
> +
> + ; ======= (5b) Trap is due to Break-Point =========
> +
> +trap_with_param:
> +
> + ;make sure orig_r8 is a positive value
> + st NR_syscalls + 2, [sp, PT_orig_r8]
> +
> + mov r0, r12
> + lr r1, [efa]
> + mov r2, sp
> +
> + ; Now that we have read EFA, its safe to do "fake" rtie
> + ; and get out of CPU exception mode
> + FAKE_RET_FROM_EXCPN r11
> +
> + ; Save callee regs in case gdb wants to have a look
> + ; SP will grow up by size of CALLEE Reg-File
> + ; NOTE: clobbers r12
> + SAVE_CALLEE_SAVED_USER
> +
> + ; save location of saved Callee Regs @ thread_struct->pc
> + GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10
> + st sp, [r10, THREAD_CALLEE_REG]
> +
> + ; Call the trap handler
> + bl do_non_swi_trap
> +
> + ; unwind stack to discard Callee saved Regs
> + DISCARD_CALLEE_SAVED_USER
> +
> + b ret_from_exception
> +
> +;##################### Trap Handling ##############################
> +;
> +; EV_Trap caused by TRAP_S and TRAP0 instructions.
> +;------------------------------------------------------------------
> +; (1) System Calls
> +; :parameters in r0-r7.
> +; :r8 has the system call number
> +; (2) Break Points
> +;------------------------------------------------------------------
> +
> +ARC_ENTRY EV_Trap
> +
> + ; Need at least 1 reg to code the early exception prolog
> + EXCPN_PROLOG_FREEUP_REG r9
> +
> + ;Which mode (user/kernel) was the system in when intr occured
> + lr r9, [erstatus]
> +
> + SWITCH_TO_KERNEL_STK
> + SAVE_ALL_TRAP
> +
> + ;------- (4) What caused the Trap --------------
> + lr r12, [ecr]
> + and.f 0, r12, ECR_PARAM_MASK
> + bnz trap_with_param
> +
> + ; ======= (5a) Trap is due to System Call ========
> +
> + ; Before doing anything, return from CPU Exception Mode
> + FAKE_RET_FROM_EXCPN r11
> +
> + ;============ This is normal System Call case ==========
> + ; Sys-call num shd not exceed the total system calls avail
> + cmp r8, NR_syscalls
> + mov.hi r0, -ENOSYS
> + bhi ret_from_system_call
> +
> + ; Offset into the syscall_table and call handler
> + ld.as r9,[sys_call_table, r8]
> + jl [r9] ; Entry into Sys Call Handler
> +
> + ; fall through to ret_from_system_call
> +ARC_EXIT EV_Trap
> +
> +ARC_ENTRY ret_from_system_call
> +
> + st r0, [sp, PT_r0] ; sys call return value in pt_regs
> +
> + ; fall through yet again to ret_from_exception
> +
> +;############# Return from Intr/Excp/Trap (Linux Specifics) ##############
> +;
> +; If ret to user mode do we need to handle signals, schedule() et al.
> +
> +ARC_ENTRY ret_from_exception
> +
> + ; Pre-{IRQ,Trap,Exception} K/U mode from pt_regs->status32
> + ld r8, [sp, PT_status32] ; returning to User/Kernel Mode
> +
> +#ifdef CONFIG_PREEMPT
> + bbit0 r8, STATUS_U_BIT, resume_kernel_mode
> +#else
> + bbit0 r8, STATUS_U_BIT, restore_regs
> +#endif
> +
> + ; Before returning to User mode check-for-and-complete any pending work
> + ; such as rescheduling/signal-delivery etc.
> +resume_user_mode_begin:
> +
> + ; Disable IRQs to ensures that chk for pending work itself is atomic
> + ; (and we don't end up missing a NEED_RESCHED/SIGPENDING due to an
> + ; interim IRQ).
> + IRQ_DISABLE r10
> +
> + ; Fast Path return to user mode if no pending work
> + GET_CURR_THR_INFO_FLAGS r9
> + and.f 0, r9, _TIF_WORK_MASK
> + bz restore_regs
> +
> + ; --- (Slow Path #1) task preemption ---
> + bbit0 r9, TIF_NEED_RESCHED, .Lchk_pend_signals
> + mov blink, resume_user_mode_begin ; tail-call to U mode ret chks
> + b @schedule ; BTST+Bnz causes relo error in link
> +
> +.Lchk_pend_signals:
> + IRQ_ENABLE r10
> +
> + ; --- (Slow Path #2) pending signal ---
> + mov r0, sp ; pt_regs for arg to do_signal()/do_notify_resume()
> +
> + bbit0 r9, TIF_SIGPENDING, .Lchk_notify_resume
> +
> + ; save CALLEE Regs.
> + ; (i) If this signal causes coredump - full regfile needed
> + ; (ii) If signal is SIGTRAP/SIGSTOP, task is being traced thus
> + ; tracer might call PEEKUSR(CALLEE reg)
> + ;
> + ; NOTE: SP will grow up by size of CALLEE Reg-File
> + SAVE_CALLEE_SAVED_USER ; clobbers r12
> +
> + ; save location of saved Callee Regs @ thread_struct->callee
> + GET_CURR_TASK_FIELD_PTR TASK_THREAD, r10
> + st sp, [r10, THREAD_CALLEE_REG]
> +
> + bl @do_signal
> +
> + ; unwind SP for cheap discard of Callee saved Regs
> + DISCARD_CALLEE_SAVED_USER
> +
> + b resume_user_mode_begin ; loop back to start of U mode ret
> +
> + ; --- (Slow Path #3) notify_resume ---
> +.Lchk_notify_resume:
> + btst r9, TIF_NOTIFY_RESUME
> + blnz @do_notify_resume
> + b resume_user_mode_begin ; unconditionally back to U mode ret chks
> + ; for single exit point from this block
> +
> +#ifdef CONFIG_PREEMPT
> +
> +resume_kernel_mode:
> +
> + ; Can't preempt if preemption disabled
> + GET_CURR_THR_INFO_FROM_SP r10
> + ld r8, [r10, THREAD_INFO_PREEMPT_COUNT]
> + brne r8, 0, restore_regs
> +
> + ; check if this task's NEED_RESCHED flag set
> + ld r9, [r10, THREAD_INFO_FLAGS]
> + bbit0 r9, TIF_NEED_RESCHED, restore_regs
> +
> + IRQ_DISABLE r9
> +
> + ; Invoke PREEMPTION
> + bl preempt_schedule_irq
> +
> + ; preempt_schedule_irq() always returns with IRQ disabled
> +#endif
> +
> + ; fall through
> +
> +;############# Return from Intr/Excp/Trap (ARC Specifics) ##############
> +;
> +; Restore the saved sys context (common exit-path for EXCPN/IRQ/Trap)
> +; IRQ shd definitely not happen between now and rtie
> +
> +restore_regs :
> +
> + ; Disable Interrupts while restoring reg-file back
> + ; XXX can this be optimised out
> + IRQ_DISABLE_SAVE r9, r10 ;@r10 has prisitine (pre-disable) copy
> +
> + ; Restore REG File. In case multiple Events outstanding,
> + ; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None
> + ; Note that we use realtime STATUS32 (not pt_regs->status32) to
> + ; decide that.
> +
> + ; if Returning from Exception
> + bbit0 r10, STATUS_AE_BIT, not_exception
> + RESTORE_ALL_SYS
> + rtie
> +
> + ; Not Exception so maybe Interrupts (Level 1 or 2)
> +
> +not_exception:
> +
> + bbit0 r10, STATUS_A1_BIT, not_level1_interrupt
> +
> + ;return from level 1
> +
> + RESTORE_ALL_INT1
> +debug_marker_l1:
> + rtie
> +
> +not_level1_interrupt:
> +
> + ;this case is for syscalls or Exceptions (with fake rtie)
> +
> + RESTORE_ALL_SYS
> +debug_marker_syscall:
> + rtie
> +
> +ARC_EXIT ret_from_exception
> +
> +ARC_ENTRY ret_from_fork
> + ; when the forked child comes here from the __switch_to function
> + ; r0 has the last task pointer.
> + ; put last task in scheduler queue
> + bl @schedule_tail
> + b @ret_from_exception
> +ARC_EXIT ret_from_fork
>
If the reworked resume user mode handling looks OK, can you please ACK it.
Thx,
-Vineet
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