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linux/arch/xtensa/kernel/coprocessor.S
Max Filippov ab5eb33641 xtensa: move coprocessor_flush to the .text section 
coprocessor_flush is not a part of fast exception handlers, but it uses
parts of fast coprocessor handling code that's why it's in the same
source file. It uses call0 opcode to invoke those parts so there are no
limitations on their relative location, but the rest of the code calls
coprocessor_flush with call8 and that doesn't work when vectors are
placed in a different gigabyte-aligned area than the rest of the kernel.

Move coprocessor_flush from the .exception.text section to the .text so
that it's reachable from the rest of the kernel with call8.

Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2021-03-08 20:15:09 -08:00

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/*
* arch/xtensa/kernel/coprocessor.S
*
* Xtensa processor configuration-specific table of coprocessor and
* other custom register layout information.
*
* 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.
*
* Copyright (C) 2003 - 2007 Tensilica Inc.
*/
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/asmmacro.h>
#include <asm/coprocessor.h>
#include <asm/current.h>
#include <asm/regs.h>
#if XTENSA_HAVE_COPROCESSORS
/*
* Macros for lazy context switch.
*/
#define SAVE_CP_REGS(x) \
.if XTENSA_HAVE_COPROCESSOR(x); \
.align 4; \
.Lsave_cp_regs_cp##x: \
xchal_cp##x##_store a2 a4 a5 a6 a7; \
jx a0; \
.endif
#define SAVE_CP_REGS_TAB(x) \
.if XTENSA_HAVE_COPROCESSOR(x); \
.long .Lsave_cp_regs_cp##x; \
.else; \
.long 0; \
.endif; \
.long THREAD_XTREGS_CP##x
#define LOAD_CP_REGS(x) \
.if XTENSA_HAVE_COPROCESSOR(x); \
.align 4; \
.Lload_cp_regs_cp##x: \
xchal_cp##x##_load a2 a4 a5 a6 a7; \
jx a0; \
.endif
#define LOAD_CP_REGS_TAB(x) \
.if XTENSA_HAVE_COPROCESSOR(x); \
.long .Lload_cp_regs_cp##x; \
.else; \
.long 0; \
.endif; \
.long THREAD_XTREGS_CP##x
__XTENSA_HANDLER
SAVE_CP_REGS(0)
SAVE_CP_REGS(1)
SAVE_CP_REGS(2)
SAVE_CP_REGS(3)
SAVE_CP_REGS(4)
SAVE_CP_REGS(5)
SAVE_CP_REGS(6)
SAVE_CP_REGS(7)
LOAD_CP_REGS(0)
LOAD_CP_REGS(1)
LOAD_CP_REGS(2)
LOAD_CP_REGS(3)
LOAD_CP_REGS(4)
LOAD_CP_REGS(5)
LOAD_CP_REGS(6)
LOAD_CP_REGS(7)
.align 4
.Lsave_cp_regs_jump_table:
SAVE_CP_REGS_TAB(0)
SAVE_CP_REGS_TAB(1)
SAVE_CP_REGS_TAB(2)
SAVE_CP_REGS_TAB(3)
SAVE_CP_REGS_TAB(4)
SAVE_CP_REGS_TAB(5)
SAVE_CP_REGS_TAB(6)
SAVE_CP_REGS_TAB(7)
.Lload_cp_regs_jump_table:
LOAD_CP_REGS_TAB(0)
LOAD_CP_REGS_TAB(1)
LOAD_CP_REGS_TAB(2)
LOAD_CP_REGS_TAB(3)
LOAD_CP_REGS_TAB(4)
LOAD_CP_REGS_TAB(5)
LOAD_CP_REGS_TAB(6)
LOAD_CP_REGS_TAB(7)
/*
* Entry condition:
*
* a0: trashed, original value saved on stack (PT_AREG0)
* a1: a1
* a2: new stack pointer, original in DEPC
* a3: a3
* depc: a2, original value saved on stack (PT_DEPC)
* excsave_1: dispatch table
*
* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
*/
ENTRY(fast_coprocessor)
/* Save remaining registers a1-a3 and SAR */
s32i a3, a2, PT_AREG3
rsr a3, sar
s32i a1, a2, PT_AREG1
s32i a3, a2, PT_SAR
mov a1, a2
rsr a2, depc
s32i a2, a1, PT_AREG2
/*
* The hal macros require up to 4 temporary registers. We use a3..a6.
*/
s32i a4, a1, PT_AREG4
s32i a5, a1, PT_AREG5
s32i a6, a1, PT_AREG6
/* Find coprocessor number. Subtract first CP EXCCAUSE from EXCCAUSE */
rsr a3, exccause
addi a3, a3, -EXCCAUSE_COPROCESSOR0_DISABLED
/* Set corresponding CPENABLE bit -> (sar:cp-index, a3: 1<<cp-index)*/
ssl a3 # SAR: 32 - coprocessor_number
movi a2, 1
rsr a0, cpenable
sll a2, a2
or a0, a0, a2
wsr a0, cpenable
rsync
/* Retrieve previous owner. (a3 still holds CP number) */
movi a0, coprocessor_owner # list of owners
addx4 a0, a3, a0 # entry for CP
l32i a4, a0, 0
beqz a4, 1f # skip 'save' if no previous owner
/* Disable coprocessor for previous owner. (a2 = 1 << CP number) */
l32i a5, a4, THREAD_CPENABLE
xor a5, a5, a2 # (1 << cp-id) still in a2
s32i a5, a4, THREAD_CPENABLE
/*
* Get context save area and 'call' save routine.
* (a4 still holds previous owner (thread_info), a3 CP number)
*/
movi a5, .Lsave_cp_regs_jump_table
movi a0, 2f # a0: 'return' address
addx8 a3, a3, a5 # a3: coprocessor number
l32i a2, a3, 4 # a2: xtregs offset
l32i a3, a3, 0 # a3: jump address
add a2, a2, a4
jx a3
/* Note that only a0 and a1 were preserved. */
2: rsr a3, exccause
addi a3, a3, -EXCCAUSE_COPROCESSOR0_DISABLED
movi a0, coprocessor_owner
addx4 a0, a3, a0
/* Set new 'owner' (a0 points to the CP owner, a3 contains the CP nr) */
1: GET_THREAD_INFO (a4, a1)
s32i a4, a0, 0
/* Get context save area and 'call' load routine. */
movi a5, .Lload_cp_regs_jump_table
movi a0, 1f
addx8 a3, a3, a5
l32i a2, a3, 4 # a2: xtregs offset
l32i a3, a3, 0 # a3: jump address
add a2, a2, a4
jx a3
/* Restore all registers and return from exception handler. */
1: l32i a6, a1, PT_AREG6
l32i a5, a1, PT_AREG5
l32i a4, a1, PT_AREG4
l32i a0, a1, PT_SAR
l32i a3, a1, PT_AREG3
l32i a2, a1, PT_AREG2
wsr a0, sar
l32i a0, a1, PT_AREG0
l32i a1, a1, PT_AREG1
rfe
ENDPROC(fast_coprocessor)
.text
/*
* coprocessor_flush(struct thread_info*, index)
* a2 a3
*
* Save coprocessor registers for coprocessor 'index'.
* The register values are saved to or loaded from the coprocessor area
* inside the task_info structure.
*
* Note that this function doesn't update the coprocessor_owner information!
*
*/
ENTRY(coprocessor_flush)
/* reserve 4 bytes on stack to save a0 */
abi_entry(4)
s32i a0, a1, 0
movi a0, .Lsave_cp_regs_jump_table
addx8 a3, a3, a0
l32i a4, a3, 4
l32i a3, a3, 0
add a2, a2, a4
beqz a3, 1f
callx0 a3
1: l32i a0, a1, 0
abi_ret(4)
ENDPROC(coprocessor_flush)
.data
ENTRY(coprocessor_owner)
.fill XCHAL_CP_MAX, 4, 0
END(coprocessor_owner)
#endif /* XTENSA_HAVE_COPROCESSORS */
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