ARC: Low level IRQ/Trap/Exception Handling

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>

1 files changed, 495 insertions, 0 deletions

diff --git a/arch/arc/include/asm/entry.h b/arch/arc/include/asm/entry.h
new file mode 100644
index 000000000000..63705b12d911
--- /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 */