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android_kernel_xiaomi_sm8350/arch/sh/kernel/cpu/sh3/entry.S
Michael Trimarchi 01ab10393c sh: Fix up DSP context save/restore. 
There were a number of issues with the DSP context save/restore code,
mostly left-over relics from when it was introduced on SH3-DSP with
little follow-up testing, resulting in things like task_pt_dspregs()
referencing incorrect state on the stack.

This follows the MIPS convention of tracking the DSP state in the
thread_struct and handling the state save/restore in switch_to() and
finish_arch_switch() respectively. The regset interface is also updated,
which allows us to finally be rid of task_pt_dspregs() and the special
cased task_pt_regs().

Signed-off-by: Michael Trimarchi <michael@evidence.eu.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2009-04-04 11:48:11 -04:00

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/*
* arch/sh/kernel/cpu/sh3/entry.S
*
* Copyright (C) 1999, 2000, 2002 Niibe Yutaka
* Copyright (C) 2003 - 2006 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 <linux/sys.h>
#include <linux/errno.h>
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/unistd.h>
#include <cpu/mmu_context.h>
#include <asm/page.h>
#include <asm/cache.h>
! 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_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 g_imask r6 /* r6_bank1 */
#define k_g_imask r6_bank /* r6_bank1 */
#define current r7 /* r7_bank1 */
#include <asm/entry-macros.S>
/*
* 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.
!
#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: 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)
/* Unwind the stack and jmp to the debug entry */
ENTRY(sh_bios_handler)
mov.l 1f, r8
bsr restore_regs
nop
lds k2, pr ! restore pr
mov k4, r15
!
mov.l 2f, k0
mov.l @k0, k0
jmp @k0
ldc k3, ssr
.align 2
1: .long 0x300000f0
2: .long gdb_vbr_vector
#endif /* CONFIG_SH_STANDARD_BIOS */
! restore_regs()
! - restore r0, r1, r2, r3, r4, r5, r6, r7 from the stack
! - switch bank
! - restore r8, r9, r10, r11, r12, r13, r14, r15 from the stack
! - restore spc, pr*, ssr, gbr, mach, macl, skip default tra
! k2 returns original pr
! k3 returns original sr
! k4 returns original stack pointer
! r8 passes SR bitmask, overwritten with restored data on return
! r9 trashed
! BL=0 on entry, on exit BL=1 (depending on r8).
ENTRY(restore_regs)
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, r9
or r8, r9
ldc r9, sr
!
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
mov.l @r15+, k2 ! original PR
mov.l @r15+, k3 ! original SR
ldc.l @r15+, gbr
lds.l @r15+, mach
lds.l @r15+, macl
rts
add #4, r15 ! Skip syscall number
restore_all:
mov.l 7f, r8
bsr restore_regs
nop
lds k2, pr ! restore pr
!
! Calculate new SR value
mov k3, k2 ! original SR value
mov #0xf0, k1
extu.b k1, k1
not k1, k1
and k1, k2 ! Mask original 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)
! Clear in_nmi
mov.l 6f, k0
mov #0, k1
mov.b k1, @k0
#endif
mov k4, r15
rte
nop
.align 2
5: .long 0x00001000 ! DSP
#ifdef CONFIG_KGDB
6: .long in_nmi
#endif
7: .long 0x30000000
! common exception handler
#include "../../entry-common.S"
! Exception Vector Base
!
! Should be aligned page boundary.
!
.balign 4096,0,4096
ENTRY(vbr_base)
.long 0
!
! 0x100: General exception vector
!
.balign 256,0,256
general_exception:
#ifndef CONFIG_CPU_SUBTYPE_SHX3
bra handle_exception
sts pr, k3 ! save original pr value in k3
#else
mov.l 1f, k4
mov.l @k4, k4
! Is EXPEVT larger than 0x800?
mov #0x8, k0
shll8 k0
cmp/hs k0, k4
bf 0f
! then add 0x580 (k2 is 0xd80 or 0xda0)
mov #0x58, k0
shll2 k0
shll2 k0
add k0, k4
0:
! Setup stack and save DSP context (k0 contains original r15 on return)
bsr prepare_stack
nop
! Save registers / Switch to bank 0
mov k4, k2 ! keep vector in k2
mov.l 1f, k4 ! SR bits to clear in k4
bsr save_regs ! needs original pr value in k3
nop
bra handle_exception_special
nop
.align 2
1: .long EXPEVT
#endif
! prepare_stack()
! - roll back gRB
! - switch to kernel stack
! k0 returns original sp (after roll back)
! k1 trashed
! k2 trashed
prepare_stack:
#ifdef CONFIG_GUSA
! Check for roll back gRB (User and Kernel)
mov r15, k0
shll k0
bf/s 1f
shll k0
bf/s 1f
stc spc, k1
stc r0_bank, k0
cmp/hs k0, k1 ! test k1 (saved PC) >= k0 (saved r0)
bt/s 2f
stc r1_bank, k1
add #-2, k0
add r15, k0
ldc k0, spc ! PC = saved r0 + r15 - 2
2: mov k1, r15 ! SP = r1
1:
#endif
! Switch to kernel stack if needed
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 >> 10), k1
shll8 k1 ! k1 := THREAD_SIZE
shll2 k1
add current, k1
mov k1, r15 ! change to kernel stack
!
1:
rts
nop
!
! 0x400: Instruction and Data TLB miss exception vector
!
.balign 1024,0,1024
tlb_miss:
sts pr, k3 ! save original pr value in k3
handle_exception:
mova exception_data, k0
! Setup stack and save DSP context (k0 contains original r15 on return)
bsr prepare_stack
PREF(k0)
! Save registers / Switch to bank 0
mov.l 5f, k2 ! vector register address
mov.l 1f, k4 ! SR bits to clear in k4
bsr save_regs ! needs original pr value in k3
mov.l @k2, k2 ! read out vector and keep in k2
handle_exception_special:
! Setup return address and jump to exception handler
mov.l 7f, r9 ! fetch return address
stc r2_bank, r0 ! k2 (vector)
mov.l 6f, r10
shlr2 r0
shlr r0
mov.l @(r0, r10), r10
jmp @r10
lds r9, pr ! put return address in pr
.align L1_CACHE_SHIFT
! save_regs()
! - save default tra, macl, mach, gbr, ssr, pr* and spc on the stack
! - save r15*, r14, r13, r12, r11, r10, r9, r8 on the stack
! - switch bank
! - save r7, r6, r5, r4, r3, r2, r1, r0 on the stack
! k0 contains original stack pointer*
! k1 trashed
! k3 passes original pr*
! k4 passes SR bitmask
! BL=1 on entry, on exit BL=0.
ENTRY(save_regs)
mov #-1, r1
mov.l k1, @-r15 ! set TRA (default: -1)
sts.l macl, @-r15
sts.l mach, @-r15
stc.l gbr, @-r15
stc.l ssr, @-r15
mov.l k3, @-r15 ! original pr in k3
stc.l spc, @-r15
mov.l k0, @-r15 ! original stack pointer in k0
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
mov.l 0f, k3 ! SR bits to set in k3
! fall-through
! save_low_regs()
! - modify SR for bank switch
! - save r7, r6, r5, r4, r3, r2, r1, r0 on the stack
! k3 passes bits to set in SR
! k4 passes bits to clear in SR
ENTRY(save_low_regs)
stc sr, r8
or k3, r8
and k4, r8
ldc r8, sr
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
rts
mov.l r0, @-r15
!
! 0x600: Interrupt / NMI vector
!
.balign 512,0,512
ENTRY(handle_interrupt)
#if defined(CONFIG_KGDB)
mov.l 2f, k2
! Debounce (filter nested NMI)
mov.l @k2, k0
mov.l 9f, k1
cmp/eq k1, k0
bf 11f
mov.l 10f, k1
tas.b @k1
bt 11f
rte
nop
.align 2
9: .long NMI_VEC
10: .long in_nmi
11:
#endif /* defined(CONFIG_KGDB) */
sts pr, k3 ! save original pr value in k3
mova exception_data, k0
! Setup stack and save DSP context (k0 contains original r15 on return)
bsr prepare_stack
PREF(k0)
! Save registers / Switch to bank 0
mov.l 1f, k4 ! SR bits to clear in k4
bsr save_regs ! needs original pr value in k3
mov #-1, k2 ! default vector kept in k2
! Setup return address and jump to do_IRQ
mov.l 4f, r9 ! fetch return address
lds r9, pr ! put return address in pr
mov.l 2f, r4
mov.l 3f, r9
mov.l @r4, r4 ! pass INTEVT vector as arg0
jmp @r9
mov r15, r5 ! pass saved registers as arg1
ENTRY(exception_none)
rts
nop
.align L1_CACHE_SHIFT
exception_data:
0: .long 0x000080f0 ! FD=1, IMASK=15
1: .long 0xcfffffff ! RB=0, BL=0
2: .long INTEVT
3: .long do_IRQ
4: .long ret_from_irq
5: .long EXPEVT
6: .long exception_handling_table
7: .long ret_from_exception
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