xtensa: keep a3 and excsave1 on entry to exception handlers (99d5040e) · Commits · jan.koester / Linux

arch/xtensa/include/asm/regs.h

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -82,6 +82,7 @@
	#define PS_CALLINC_SHIFT 16		#define PS_CALLINC_SHIFT 16
	#define PS_CALLINC_MASK 0x00030000		#define PS_CALLINC_MASK 0x00030000
	#define PS_OWB_SHIFT 8		#define PS_OWB_SHIFT 8
			#define PS_OWB_WIDTH 4
	#define PS_OWB_MASK 0x00000F00		#define PS_OWB_MASK 0x00000F00
	#define PS_RING_SHIFT 6		#define PS_RING_SHIFT 6
	#define PS_RING_MASK 0x000000C0		#define PS_RING_MASK 0x000000C0

arch/xtensa/kernel/align.S

+2 −3

Original line number	Original line	Diff line number	Diff line
	@@ -146,9 +146,9 @@
	* a0: trashed, original value saved on stack (PT_AREG0)		* a0: trashed, original value saved on stack (PT_AREG0)
	* a1: a1		* a1: a1
	* a2: new stack pointer, original in DEPC		* a2: new stack pointer, original in DEPC
	* a3: dispatch table		* a3: a3
	* depc: a2, original value saved on stack (PT_DEPC)		* depc: a2, original value saved on stack (PT_DEPC)
	* excsave_1: a3		* excsave_1: dispatch table
	*		*
	* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC		* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
	* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception		* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
	@@ -171,7 +171,6 @@ ENTRY(fast_unaligned)
	s32i a8, a2, PT_AREG8		s32i a8, a2, PT_AREG8

	rsr a0, depc		rsr a0, depc
	xsr a3, excsave1
	s32i a0, a2, PT_AREG2		s32i a0, a2, PT_AREG2
	s32i a3, a2, PT_AREG3		s32i a3, a2, PT_AREG3

arch/xtensa/kernel/coprocessor.S

+4 −5

Original line number	Original line	Diff line number	Diff line
	@@ -32,9 +32,9 @@
	* a0: trashed, original value saved on stack (PT_AREG0)		* a0: trashed, original value saved on stack (PT_AREG0)
	* a1: a1		* a1: a1
	* a2: new stack pointer, original in DEPC		* a2: new stack pointer, original in DEPC
	* a3: dispatch table		* a3: a3
	* depc: a2, original value saved on stack (PT_DEPC)		* depc: a2, original value saved on stack (PT_DEPC)
	* excsave_1: a3		* excsave_1: dispatch table
	*		*
	* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC		* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
	* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception		* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
	@@ -225,9 +225,9 @@ ENDPROC(coprocessor_restore)
	* a0: trashed, original value saved on stack (PT_AREG0)		* a0: trashed, original value saved on stack (PT_AREG0)
	* a1: a1		* a1: a1
	* a2: new stack pointer, original in DEPC		* a2: new stack pointer, original in DEPC
	* a3: dispatch table		* a3: a3
	* depc: a2, original value saved on stack (PT_DEPC)		* depc: a2, original value saved on stack (PT_DEPC)
	* excsave_1: a3		* excsave_1: dispatch table
	*		*
	* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC		* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
	* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception		* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
	@@ -245,7 +245,6 @@ ENTRY(fast_coprocessor)

	/* Save remaining registers a1-a3 and SAR */		/* Save remaining registers a1-a3 and SAR */

	xsr a3, excsave1
	s32i a3, a2, PT_AREG3		s32i a3, a2, PT_AREG3
	rsr a3, sar		rsr a3, sar
	s32i a1, a2, PT_AREG1		s32i a1, a2, PT_AREG1

arch/xtensa/kernel/entry.S

+47 −68

Original line number	Original line	Diff line number	Diff line
	@@ -91,9 +91,9 @@
	* a0: trashed, original value saved on stack (PT_AREG0)		* a0: trashed, original value saved on stack (PT_AREG0)
	* a1: a1		* a1: a1
	* a2: new stack pointer, original value in depc		* a2: new stack pointer, original value in depc
	* a3: dispatch table		* a3: a3
	* depc: a2, original value saved on stack (PT_DEPC)		* depc: a2, original value saved on stack (PT_DEPC)
	* excsave1: a3		* excsave1: dispatch table
	*		*
	* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC		* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
	* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception		* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
	@@ -109,9 +109,8 @@

	ENTRY(user_exception)		ENTRY(user_exception)

	/* Save a2, a3, and depc, restore excsave_1 and set SP. */		/* Save a1, a2, a3, and set SP. */

	xsr a3, excsave1
	rsr a0, depc		rsr a0, depc
	s32i a1, a2, PT_AREG1		s32i a1, a2, PT_AREG1
	s32i a0, a2, PT_AREG2		s32i a0, a2, PT_AREG2
	@@ -237,9 +236,9 @@ ENDPROC(user_exception)
	* a0: trashed, original value saved on stack (PT_AREG0)		* a0: trashed, original value saved on stack (PT_AREG0)
	* a1: a1		* a1: a1
	* a2: new stack pointer, original in DEPC		* a2: new stack pointer, original in DEPC
	* a3: dispatch table		* a3: a3
	* depc: a2, original value saved on stack (PT_DEPC)		* depc: a2, original value saved on stack (PT_DEPC)
	* excsave_1: a3		* excsave_1: dispatch table
	*		*
	* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC		* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
	* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception		* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
	@@ -255,9 +254,8 @@ ENDPROC(user_exception)

	ENTRY(kernel_exception)		ENTRY(kernel_exception)

	/* Save a0, a2, a3, DEPC and set SP. */		/* Save a1, a2, a3, and set SP. */

	xsr a3, excsave1 # restore a3, excsave_1
	rsr a0, depc # get a2		rsr a0, depc # get a2
	s32i a1, a2, PT_AREG1		s32i a1, a2, PT_AREG1
	s32i a0, a2, PT_AREG2		s32i a0, a2, PT_AREG2
	@@ -408,7 +406,7 @@ common_exception:
	* exception handler and call the exception handler.		* exception handler and call the exception handler.
	*/		*/

	movi a4, exc_table		rsr a4, excsave1
	mov a6, a1 # pass stack frame		mov a6, a1 # pass stack frame
	mov a7, a0 # pass EXCCAUSE		mov a7, a0 # pass EXCCAUSE
	addx4 a4, a0, a4		addx4 a4, a0, a4
	@@ -832,9 +830,9 @@ ENDPROC(unrecoverable_exception)
	* a0: trashed, original value saved on stack (PT_AREG0)		* a0: trashed, original value saved on stack (PT_AREG0)
	* a1: a1		* a1: a1
	* a2: new stack pointer, original in DEPC		* a2: new stack pointer, original in DEPC
	* a3: dispatch table		* a3: a3
	* depc: a2, original value saved on stack (PT_DEPC)		* depc: a2, original value saved on stack (PT_DEPC)
	* excsave_1: a3		* excsave_1: dispatch table
	*		*
	* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC		* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
	* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception		* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
	@@ -857,18 +855,16 @@ ENTRY(fast_alloca)

	rsr a0, depc # get a2		rsr a0, depc # get a2
	s32i a4, a2, PT_AREG4 # save a4 and		s32i a4, a2, PT_AREG4 # save a4 and
			s32i a3, a2, PT_AREG3
	s32i a0, a2, PT_AREG2 # a2 to stack		s32i a0, a2, PT_AREG2 # a2 to stack

	/* Exit critical section. */		/* Exit critical section. */

	movi a0, 0		movi a0, 0
			rsr a3, excsave1
	s32i a0, a3, EXC_TABLE_FIXUP		s32i a0, a3, EXC_TABLE_FIXUP

	/* Restore a3, excsave_1 */

	xsr a3, excsave1 # make sure excsave_1 is valid for dbl.
	rsr a4, epc1 # get exception address		rsr a4, epc1 # get exception address
	s32i a3, a2, PT_AREG3 # save a3 to stack

	#ifdef ALLOCA_EXCEPTION_IN_IRAM		#ifdef ALLOCA_EXCEPTION_IN_IRAM
	#error iram not supported		#error iram not supported
	@@ -1007,9 +1003,9 @@ ENDPROC(fast_alloca)
	* a0: trashed, original value saved on stack (PT_AREG0)		* a0: trashed, original value saved on stack (PT_AREG0)
	* a1: a1		* a1: a1
	* a2: new stack pointer, original in DEPC		* a2: new stack pointer, original in DEPC
	* a3: dispatch table		* a3: a3
	* depc: a2, original value saved on stack (PT_DEPC)		* depc: a2, original value saved on stack (PT_DEPC)
	* excsave_1: a3		* excsave_1: dispatch table
	*/		*/

	ENTRY(fast_syscall_kernel)		ENTRY(fast_syscall_kernel)
	@@ -1056,7 +1052,6 @@ ENTRY(fast_syscall_unrecoverable)

	l32i a0, a2, PT_AREG0 # restore a0		l32i a0, a2, PT_AREG0 # restore a0
	xsr a2, depc # restore a2, depc		xsr a2, depc # restore a2, depc
	rsr a3, excsave1

	wsr a0, excsave1		wsr a0, excsave1
	movi a0, unrecoverable_exception		movi a0, unrecoverable_exception
	@@ -1078,10 +1073,10 @@ ENDPROC(fast_syscall_unrecoverable)
	* a0: a2 (syscall-nr), original value saved on stack (PT_AREG0)		* a0: a2 (syscall-nr), original value saved on stack (PT_AREG0)
	* a1: a1		* a1: a1
	* a2: new stack pointer, original in a0 and DEPC		* a2: new stack pointer, original in a0 and DEPC
	* a3: dispatch table, original in excsave_1		* a3: a3
	* a4..a15: unchanged		* a4..a15: unchanged
	* depc: a2, original value saved on stack (PT_DEPC)		* depc: a2, original value saved on stack (PT_DEPC)
	* excsave_1: a3		* excsave_1: dispatch table
	*		*
	* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC		* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
	* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception		* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
	@@ -1114,8 +1109,6 @@ ENDPROC(fast_syscall_unrecoverable)

	ENTRY(fast_syscall_xtensa)		ENTRY(fast_syscall_xtensa)

	xsr a3, excsave1 # restore a3, excsave1

	s32i a7, a2, PT_AREG7 # we need an additional register		s32i a7, a2, PT_AREG7 # we need an additional register
	movi a7, 4 # sizeof(unsigned int)		movi a7, 4 # sizeof(unsigned int)
	access_ok a3, a7, a0, a2, .Leac # a0: scratch reg, a2: sp		access_ok a3, a7, a0, a2, .Leac # a0: scratch reg, a2: sp
	@@ -1178,9 +1171,9 @@ ENDPROC(fast_syscall_xtensa)
	* a0: trashed, original value saved on stack (PT_AREG0)		* a0: trashed, original value saved on stack (PT_AREG0)
	* a1: a1		* a1: a1
	* a2: new stack pointer, original in DEPC		* a2: new stack pointer, original in DEPC
	* a3: dispatch table		* a3: a3
	* depc: a2, original value saved on stack (PT_DEPC)		* depc: a2, original value saved on stack (PT_DEPC)
	* excsave_1: a3		* excsave_1: dispatch table
	*		*
	* Note: We assume the stack pointer is EXC_TABLE_KSTK in the fixup handler.		* Note: We assume the stack pointer is EXC_TABLE_KSTK in the fixup handler.
	*/		*/
	@@ -1189,15 +1182,16 @@ ENTRY(fast_syscall_spill_registers)

	/* Register a FIXUP handler (pass current wb as a parameter) */		/* Register a FIXUP handler (pass current wb as a parameter) */

			xsr a3, excsave1
	movi a0, fast_syscall_spill_registers_fixup		movi a0, fast_syscall_spill_registers_fixup
	s32i a0, a3, EXC_TABLE_FIXUP		s32i a0, a3, EXC_TABLE_FIXUP
	rsr a0, windowbase		rsr a0, windowbase
	s32i a0, a3, EXC_TABLE_PARAM		s32i a0, a3, EXC_TABLE_PARAM
			xsr a3, excsave1 # restore a3 and excsave_1

	/* Save a3 and SAR on stack. */		/* Save a3, a4 and SAR on stack. */

	rsr a0, sar		rsr a0, sar
	xsr a3, excsave1 # restore a3 and excsave_1
	s32i a3, a2, PT_AREG3		s32i a3, a2, PT_AREG3
	s32i a4, a2, PT_AREG4		s32i a4, a2, PT_AREG4
	s32i a0, a2, PT_AREG5 # store SAR to PT_AREG5		s32i a0, a2, PT_AREG5 # store SAR to PT_AREG5
	@@ -1251,14 +1245,14 @@ fast_syscall_spill_registers_fixup:
	* in WS, so that the exception handlers save them to the task stack.		* in WS, so that the exception handlers save them to the task stack.
	*/		*/

	rsr a3, excsave1 # get spill-mask		xsr a3, excsave1 # get spill-mask
	slli a2, a3, 1 # shift left by one		slli a2, a3, 1 # shift left by one

	slli a3, a2, 32-WSBITS		slli a3, a2, 32-WSBITS
	src a2, a2, a3 # a1 = xxwww1yyxxxwww1yy......		src a2, a2, a3 # a1 = xxwww1yyxxxwww1yy......
	wsr a2, windowstart # set corrected windowstart		wsr a2, windowstart # set corrected windowstart

	movi a3, exc_table		rsr a3, excsave1
	l32i a2, a3, EXC_TABLE_DOUBLE_SAVE # restore a2		l32i a2, a3, EXC_TABLE_DOUBLE_SAVE # restore a2
	l32i a3, a3, EXC_TABLE_PARAM # original WB (in user task)		l32i a3, a3, EXC_TABLE_PARAM # original WB (in user task)

	@@ -1295,7 +1289,7 @@ fast_syscall_spill_registers_fixup:

	/* Jump to the exception handler. */		/* Jump to the exception handler. */

	movi a3, exc_table		rsr a3, excsave1
	rsr a0, exccause		rsr a0, exccause
	addx4 a0, a0, a3 # find entry in table		addx4 a0, a0, a3 # find entry in table
	l32i a0, a0, EXC_TABLE_FAST_USER # load handler		l32i a0, a0, EXC_TABLE_FAST_USER # load handler
	@@ -1312,6 +1306,7 @@ fast_syscall_spill_registers_fixup_return:
	xsr a3, excsave1		xsr a3, excsave1
	movi a2, fast_syscall_spill_registers_fixup		movi a2, fast_syscall_spill_registers_fixup
	s32i a2, a3, EXC_TABLE_FIXUP		s32i a2, a3, EXC_TABLE_FIXUP
			s32i a0, a3, EXC_TABLE_DOUBLE_SAVE
	rsr a2, windowbase		rsr a2, windowbase
	s32i a2, a3, EXC_TABLE_PARAM		s32i a2, a3, EXC_TABLE_PARAM
	l32i a2, a3, EXC_TABLE_KSTK		l32i a2, a3, EXC_TABLE_KSTK
	@@ -1323,11 +1318,6 @@ fast_syscall_spill_registers_fixup_return:
	wsr a3, windowbase		wsr a3, windowbase
	rsync		rsync

	/* Restore a3 and return. */

	movi a3, exc_table
	xsr a3, excsave1

	rfde		rfde


	@@ -1514,9 +1504,8 @@ ENTRY(_spill_registers)

	movi a0, 0		movi a0, 0

	movi a3, exc_table		rsr a3, excsave1
	l32i a1, a3, EXC_TABLE_KSTK		l32i a1, a3, EXC_TABLE_KSTK
	wsr a3, excsave1

	movi a4, (1 << PS_WOE_BIT) \| LOCKLEVEL		movi a4, (1 << PS_WOE_BIT) \| LOCKLEVEL
	wsr a4, ps		wsr a4, ps
	@@ -1560,9 +1549,9 @@ ENDPROC(fast_second_level_miss_double_kernel)
	* a0: trashed, original value saved on stack (PT_AREG0)		* a0: trashed, original value saved on stack (PT_AREG0)
	* a1: a1		* a1: a1
	* a2: new stack pointer, original in DEPC		* a2: new stack pointer, original in DEPC
	* a3: dispatch table		* a3: a3
	* depc: a2, original value saved on stack (PT_DEPC)		* depc: a2, original value saved on stack (PT_DEPC)
	* excsave_1: a3		* excsave_1: dispatch table
	*		*
	* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC		* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
	* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception		* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
	@@ -1570,9 +1559,10 @@ ENDPROC(fast_second_level_miss_double_kernel)

	ENTRY(fast_second_level_miss)		ENTRY(fast_second_level_miss)

	/* Save a1. Note: we don't expect a double exception. */		/* Save a1 and a3. Note: we don't expect a double exception. */

	s32i a1, a2, PT_AREG1		s32i a1, a2, PT_AREG1
			s32i a3, a2, PT_AREG3

	/* We need to map the page of PTEs for the user task. Find		/* We need to map the page of PTEs for the user task. Find
	* the pointer to that page. Also, it's possible for tsk->mm		* the pointer to that page. Also, it's possible for tsk->mm
	@@ -1594,9 +1584,6 @@ ENTRY(fast_second_level_miss)
	l32i a0, a1, TASK_MM # tsk->mm		l32i a0, a1, TASK_MM # tsk->mm
	beqz a0, 9f		beqz a0, 9f


	/* We deliberately destroy a3 that holds the exception table. */

	8: rsr a3, excvaddr # fault address		8: rsr a3, excvaddr # fault address
	_PGD_OFFSET(a0, a3, a1)		_PGD_OFFSET(a0, a3, a1)
	l32i a0, a0, 0 # read pmdval		l32i a0, a0, 0 # read pmdval
	@@ -1647,7 +1634,7 @@ ENTRY(fast_second_level_miss)

	/* Exit critical section. */		/* Exit critical section. */

	4: movi a3, exc_table # restore a3		4: rsr a3, excsave1
	movi a0, 0		movi a0, 0
	s32i a0, a3, EXC_TABLE_FIXUP		s32i a0, a3, EXC_TABLE_FIXUP

	@@ -1655,8 +1642,8 @@ ENTRY(fast_second_level_miss)

	l32i a0, a2, PT_AREG0		l32i a0, a2, PT_AREG0
	l32i a1, a2, PT_AREG1		l32i a1, a2, PT_AREG1
			l32i a3, a2, PT_AREG3
	l32i a2, a2, PT_DEPC		l32i a2, a2, PT_DEPC
	xsr a3, excsave1

	bgeui a2, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f		bgeui a2, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f

	@@ -1743,11 +1730,8 @@ ENTRY(fast_second_level_miss)

	2: /* Invalid PGD, default exception handling */		2: /* Invalid PGD, default exception handling */

	movi a3, exc_table
	rsr a1, depc		rsr a1, depc
	xsr a3, excsave1
	s32i a1, a2, PT_AREG2		s32i a1, a2, PT_AREG2
	s32i a3, a2, PT_AREG3
	mov a1, a2		mov a1, a2

	rsr a2, ps		rsr a2, ps
	@@ -1767,9 +1751,9 @@ ENDPROC(fast_second_level_miss)
	* a0: trashed, original value saved on stack (PT_AREG0)		* a0: trashed, original value saved on stack (PT_AREG0)
	* a1: a1		* a1: a1
	* a2: new stack pointer, original in DEPC		* a2: new stack pointer, original in DEPC
	* a3: dispatch table		* a3: a3
	* depc: a2, original value saved on stack (PT_DEPC)		* depc: a2, original value saved on stack (PT_DEPC)
	* excsave_1: a3		* excsave_1: dispatch table
	*		*
	* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC		* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
	* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception		* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
	@@ -1777,17 +1761,17 @@ ENDPROC(fast_second_level_miss)

	ENTRY(fast_store_prohibited)		ENTRY(fast_store_prohibited)

	/* Save a1 and a4. */		/* Save a1 and a3. */

	s32i a1, a2, PT_AREG1		s32i a1, a2, PT_AREG1
	s32i a4, a2, PT_AREG4		s32i a3, a2, PT_AREG3

	GET_CURRENT(a1,a2)		GET_CURRENT(a1,a2)
	l32i a0, a1, TASK_MM # tsk->mm		l32i a0, a1, TASK_MM # tsk->mm
	beqz a0, 9f		beqz a0, 9f

	8: rsr a1, excvaddr # fault address		8: rsr a1, excvaddr # fault address
	_PGD_OFFSET(a0, a1, a4)		_PGD_OFFSET(a0, a1, a3)
	l32i a0, a0, 0		l32i a0, a0, 0
	beqz a0, 2f		beqz a0, 2f

	@@ -1796,39 +1780,37 @@ ENTRY(fast_store_prohibited)
	* and is not PAGE_NONE. See pgtable.h for possible PTE layouts.		* and is not PAGE_NONE. See pgtable.h for possible PTE layouts.
	*/		*/

	_PTE_OFFSET(a0, a1, a4)		_PTE_OFFSET(a0, a1, a3)
	l32i a4, a0, 0 # read pteval		l32i a3, a0, 0 # read pteval
	movi a1, _PAGE_CA_INVALID		movi a1, _PAGE_CA_INVALID
	ball a4, a1, 2f		ball a3, a1, 2f
	bbci.l a4, _PAGE_WRITABLE_BIT, 2f		bbci.l a3, _PAGE_WRITABLE_BIT, 2f

	movi a1, _PAGE_ACCESSED \| _PAGE_DIRTY \| _PAGE_HW_WRITE		movi a1, _PAGE_ACCESSED \| _PAGE_DIRTY \| _PAGE_HW_WRITE
	or a4, a4, a1		or a3, a3, a1
	rsr a1, excvaddr		rsr a1, excvaddr
	s32i a4, a0, 0		s32i a3, a0, 0

	/* We need to flush the cache if we have page coloring. */		/* We need to flush the cache if we have page coloring. */
	#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK		#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK
	dhwb a0, 0		dhwb a0, 0
	#endif		#endif
	pdtlb a0, a1		pdtlb a0, a1
	wdtlb a4, a0		wdtlb a3, a0

	/* Exit critical section. */		/* Exit critical section. */

	movi a0, 0		movi a0, 0
			rsr a3, excsave1
	s32i a0, a3, EXC_TABLE_FIXUP		s32i a0, a3, EXC_TABLE_FIXUP

	/* Restore the working registers, and return. */		/* Restore the working registers, and return. */

	l32i a4, a2, PT_AREG4		l32i a3, a2, PT_AREG3
	l32i a1, a2, PT_AREG1		l32i a1, a2, PT_AREG1
	l32i a0, a2, PT_AREG0		l32i a0, a2, PT_AREG0
	l32i a2, a2, PT_DEPC		l32i a2, a2, PT_DEPC

	/* Restore excsave1 and a3. */

	xsr a3, excsave1
	bgeui a2, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f		bgeui a2, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f

	rsr a2, depc		rsr a2, depc
	@@ -1845,11 +1827,8 @@ ENTRY(fast_store_prohibited)

	2: /* If there was a problem, handle fault in C */		2: /* If there was a problem, handle fault in C */

	rsr a4, depc # still holds a2		rsr a3, depc # still holds a2
	xsr a3, excsave1		s32i a3, a2, PT_AREG2
	s32i a4, a2, PT_AREG2
	s32i a3, a2, PT_AREG3
	l32i a4, a2, PT_AREG4
	mov a1, a2		mov a1, a2

	rsr a2, ps		rsr a2, ps

arch/xtensa/kernel/vectors.S

+184 −66

Original line number	Original line	Diff line number	Diff line
	@@ -78,6 +78,7 @@ ENTRY(_UserExceptionVector)
	s32i a0, a2, PT_DEPC # mark it as a regular exception		s32i a0, a2, PT_DEPC # mark it as a regular exception
	addx4 a0, a0, a3 # find entry in table		addx4 a0, a0, a3 # find entry in table
	l32i a0, a0, EXC_TABLE_FAST_USER # load handler		l32i a0, a0, EXC_TABLE_FAST_USER # load handler
			xsr a3, excsave1 # restore a3 and dispatch table
	jx a0		jx a0

	ENDPROC(_UserExceptionVector)		ENDPROC(_UserExceptionVector)
	@@ -104,6 +105,7 @@ ENTRY(_KernelExceptionVector)
	s32i a0, a2, PT_DEPC # mark it as a regular exception		s32i a0, a2, PT_DEPC # mark it as a regular exception
	addx4 a0, a0, a3 # find entry in table		addx4 a0, a0, a3 # find entry in table
	l32i a0, a0, EXC_TABLE_FAST_KERNEL # load handler address		l32i a0, a0, EXC_TABLE_FAST_KERNEL # load handler address
			xsr a3, excsave1 # restore a3 and dispatch table
	jx a0		jx a0

	ENDPROC(_KernelExceptionVector)		ENDPROC(_KernelExceptionVector)
	@@ -168,7 +170,7 @@ ENDPROC(_KernelExceptionVector)
	*		*
	* a0: DEPC		* a0: DEPC
	* a1: a1		* a1: a1
	* a2: trashed, original value in EXC_TABLE_DOUBLE_A2		* a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE
	* a3: exctable		* a3: exctable
	* depc: a0		* depc: a0
	* excsave_1: a3		* excsave_1: a3
	@@ -204,47 +206,46 @@ ENDPROC(_KernelExceptionVector)

	.section .DoubleExceptionVector.text, "ax"		.section .DoubleExceptionVector.text, "ax"
	.begin literal_prefix .DoubleExceptionVector		.begin literal_prefix .DoubleExceptionVector
			.globl _DoubleExceptionVector_WindowUnderflow
			.globl _DoubleExceptionVector_WindowOverflow

	ENTRY(_DoubleExceptionVector)		ENTRY(_DoubleExceptionVector)

	/* Deliberately destroy excsave (don't assume it's value was valid). */		xsr a3, excsave1
			s32i a2, a3, EXC_TABLE_DOUBLE_SAVE
	wsr a3, excsave1 # save a3

	/* Check for kernel double exception (usually fatal). */		/* Check for kernel double exception (usually fatal). */

	rsr a3, ps		rsr a2, ps
	_bbci.l a3, PS_UM_BIT, .Lksp		_bbci.l a2, PS_UM_BIT, .Lksp

	/* Check if we are currently handling a window exception. */		/* Check if we are currently handling a window exception. */
	/* Note: We don't need to indicate that we enter a critical section. */		/* Note: We don't need to indicate that we enter a critical section. */

	xsr a0, depc # get DEPC, save a0		xsr a0, depc # get DEPC, save a0

	movi a3, WINDOW_VECTORS_VADDR		movi a2, WINDOW_VECTORS_VADDR
	_bltu a0, a3, .Lfixup		_bltu a0, a2, .Lfixup
	addi a3, a3, WINDOW_VECTORS_SIZE		addi a2, a2, WINDOW_VECTORS_SIZE
	_bgeu a0, a3, .Lfixup		_bgeu a0, a2, .Lfixup

	/* Window overflow/underflow exception. Get stack pointer. */		/* Window overflow/underflow exception. Get stack pointer. */

	mov a3, a2		l32i a2, a3, EXC_TABLE_KSTK
	/* This explicit literal and the following references to it are made
	* in order to fit DoubleExceptionVector.literals into the available
	* 16-byte gap before DoubleExceptionVector.text in the absence of
	* link time relaxation. See kernel/vmlinux.lds.S
	*/
	.literal .Lexc_table, exc_table
	l32r a2, .Lexc_table
	l32i a2, a2, EXC_TABLE_KSTK

	/* Check for overflow/underflow exception, jump if overflow. */		/* Check for overflow/underflow exception, jump if overflow. */

	_bbci.l a0, 6, .Lovfl		_bbci.l a0, 6, _DoubleExceptionVector_WindowOverflow

	/* a0: depc, a1: a1, a2: kstk, a3: a2, depc: a0, excsave: a3 */		/*
			* Restart window underflow exception.
	/* Restart window underflow exception.		* Currently:
			* depc = orig a0,
			* a0 = orig DEPC,
			* a2 = new sp based on KSTK from exc_table
			* a3 = excsave_1
			* excsave_1 = orig a3
			*
	* We return to the instruction in user space that caused the window		* We return to the instruction in user space that caused the window
	* underflow exception. Therefore, we change window base to the value		* underflow exception. Therefore, we change window base to the value
	* before we entered the window underflow exception and prepare the		* before we entered the window underflow exception and prepare the
	@@ -252,10 +253,11 @@ ENTRY(_DoubleExceptionVector)
	* by changing depc (in a0).		* by changing depc (in a0).
	* Note: We can trash the current window frame (a0...a3) and depc!		* Note: We can trash the current window frame (a0...a3) and depc!
	*/		*/
			_DoubleExceptionVector_WindowUnderflow:
			xsr a3, excsave1
	wsr a2, depc # save stack pointer temporarily		wsr a2, depc # save stack pointer temporarily
	rsr a0, ps		rsr a0, ps
	extui a0, a0, PS_OWB_SHIFT, 4		extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
	wsr a0, windowbase		wsr a0, windowbase
	rsync		rsync

	@@ -263,28 +265,57 @@ ENTRY(_DoubleExceptionVector)

	xsr a2, depc # save a2 and get stack pointer		xsr a2, depc # save a2 and get stack pointer
	s32i a0, a2, PT_AREG0		s32i a0, a2, PT_AREG0
			xsr a3, excsave1
	wsr a3, excsave1 # save a3
	l32r a3, .Lexc_table

	rsr a0, exccause		rsr a0, exccause
	s32i a0, a2, PT_DEPC # mark it as a regular exception		s32i a0, a2, PT_DEPC # mark it as a regular exception
	addx4 a0, a0, a3		addx4 a0, a0, a3
			xsr a3, excsave1
	l32i a0, a0, EXC_TABLE_FAST_USER		l32i a0, a0, EXC_TABLE_FAST_USER
	jx a0		jx a0

	.Lfixup:/* Check for a fixup handler or if we were in a critical section. */		/*
			* We only allow the ITLB miss exception if we are in kernel space.
			* All other exceptions are unexpected and thus unrecoverable!
			*/

			#ifdef CONFIG_MMU
			.extern fast_second_level_miss_double_kernel

			.Lksp: /* a0: a0, a1: a1, a2: a2, a3: trashed, depc: depc, excsave: a3 */

			rsr a3, exccause
			beqi a3, EXCCAUSE_ITLB_MISS, 1f
			addi a3, a3, -EXCCAUSE_DTLB_MISS
			bnez a3, .Lunrecoverable
			1: movi a3, fast_second_level_miss_double_kernel
			jx a3
			#else
			.equ .Lksp, .Lunrecoverable
			#endif

	/* a0: depc, a1: a1, a2: a2, a3: trashed, depc: a0, excsave1: a3 */		/* Critical! We can't handle this situation. PANIC! */

	l32r a3, .Lexc_table		.extern unrecoverable_exception
	s32i a2, a3, EXC_TABLE_DOUBLE_SAVE # temporary variable
			.Lunrecoverable_fixup:
			l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
			xsr a0, depc

			.Lunrecoverable:
			rsr a3, excsave1
			wsr a0, excsave1
			movi a0, unrecoverable_exception
			callx0 a0

			.Lfixup:/* Check for a fixup handler or if we were in a critical section. */

			/* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave1: a3 */

	/* Enter critical section. */		/* Enter critical section. */

	l32i a2, a3, EXC_TABLE_FIXUP		l32i a2, a3, EXC_TABLE_FIXUP
	s32i a3, a3, EXC_TABLE_FIXUP		s32i a3, a3, EXC_TABLE_FIXUP
	beq a2, a3, .Lunrecoverable_fixup # critical!		beq a2, a3, .Lunrecoverable_fixup # critical section
	beqz a2, .Ldflt # no handler was registered		beqz a2, .Ldflt # no handler was registered

	/* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave: a3 */		/* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave: a3 */
	@@ -293,58 +324,145 @@ ENTRY(_DoubleExceptionVector)

	.Ldflt: /* Get stack pointer. */		.Ldflt: /* Get stack pointer. */

	l32i a3, a3, EXC_TABLE_DOUBLE_SAVE		l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
	addi a2, a3, -PT_USER_SIZE		addi a2, a2, -PT_USER_SIZE

	.Lovfl: /* Jump to default handlers. */

	/* a0: depc, a1: a1, a2: kstk, a3: a2, depc: a0, excsave: a3 */		/* a0: depc, a1: a1, a2: kstk, a3: exctable, depc: a0, excsave: a3 */

	xsr a3, depc
	s32i a0, a2, PT_DEPC		s32i a0, a2, PT_DEPC
	s32i a3, a2, PT_AREG0		l32i a0, a3, EXC_TABLE_DOUBLE_SAVE
			xsr a0, depc
			s32i a0, a2, PT_AREG0

	/* a0: avail, a1: a1, a2: kstk, a3: avail, depc: a2, excsave: a3 */		/* a0: avail, a1: a1, a2: kstk, a3: exctable, depc: a2, excsave: a3 */

	l32r a3, .Lexc_table
	rsr a0, exccause		rsr a0, exccause
	addx4 a0, a0, a3		addx4 a0, a0, a3
			xsr a3, excsave1
	l32i a0, a0, EXC_TABLE_FAST_USER		l32i a0, a0, EXC_TABLE_FAST_USER
	jx a0		jx a0

	/*		/*
	* We only allow the ITLB miss exception if we are in kernel space.		* Restart window OVERFLOW exception.
	* All other exceptions are unexpected and thus unrecoverable!		* Currently:
			* depc = orig a0,
			* a0 = orig DEPC,
			* a2 = new sp based on KSTK from exc_table
			* a3 = EXCSAVE_1
			* excsave_1 = orig a3
			*
			* We return to the instruction in user space that caused the window
			* overflow exception. Therefore, we change window base to the value
			* before we entered the window overflow exception and prepare the
			* registers to return as if we were coming from a regular exception
			* by changing DEPC (in a0).
			*
			* NOTE: We CANNOT trash the current window frame (a0...a3), but we
			* can clobber depc.
			*
			* The tricky part here is that overflow8 and overflow12 handlers
			* save a0, then clobber a0. To restart the handler, we have to restore
			* a0 if the double exception was past the point where a0 was clobbered.
			*
			* To keep things simple, we take advantage of the fact all overflow
			* handlers save a0 in their very first instruction. If DEPC was past
			* that instruction, we can safely restore a0 from where it was saved
			* on the stack.
			*
			* a0: depc, a1: a1, a2: kstk, a3: exc_table, depc: a0, excsave1: a3
	*/		*/
			_DoubleExceptionVector_WindowOverflow:
			extui a2, a0, 0, 6 # get offset into 64-byte vector handler
			beqz a2, 1f # if at start of vector, don't restore

	#ifdef CONFIG_MMU		addi a0, a0, -128
	.extern fast_second_level_miss_double_kernel		bbsi a0, 8, 1f # don't restore except for overflow 8 and 12
			bbsi a0, 7, 2f

	.Lksp: /* a0: a0, a1: a1, a2: a2, a3: trashed, depc: depc, excsave: a3 */		/*
			* Restore a0 as saved by _WindowOverflow8().
			*
			* FIXME: we really need a fixup handler for this L32E,
			* for the extremely unlikely case where the overflow handler's
			* reference thru a0 gets a hardware TLB refill that bumps out
			* the (distinct, aliasing) TLB entry that mapped its prior
			* references thru a9, and where our reference now thru a9
			* gets a 2nd-level miss exception (not hardware TLB refill).
			*/

	rsr a3, exccause		l32e a2, a9, -16
	beqi a3, EXCCAUSE_ITLB_MISS, 1f		wsr a2, depc # replace the saved a0
	addi a3, a3, -EXCCAUSE_DTLB_MISS		j 1f
	bnez a3, .Lunrecoverable
	1: movi a3, fast_second_level_miss_double_kernel
	jx a3
	#else
	.equ .Lksp, .Lunrecoverable
	#endif

	/* Critical! We can't handle this situation. PANIC! */		2:
			/*
			* Restore a0 as saved by _WindowOverflow12().
			*
			* FIXME: we really need a fixup handler for this L32E,
			* for the extremely unlikely case where the overflow handler's
			* reference thru a0 gets a hardware TLB refill that bumps out
			* the (distinct, aliasing) TLB entry that mapped its prior
			* references thru a13, and where our reference now thru a13
			* gets a 2nd-level miss exception (not hardware TLB refill).
			*/

	.extern unrecoverable_exception		l32e a2, a13, -16
			wsr a2, depc # replace the saved a0
			1:
			/*
			* Restore WindowBase while leaving all address registers restored.
			* We have to use ROTW for this, because WSR.WINDOWBASE requires
			* an address register (which would prevent restore).
			*
			* Window Base goes from 0 ... 7 (Module 8)
			* Window Start is 8 bits; Ex: (0b1010 1010):0x55 from series of call4s
			*/

			rsr a0, ps
			extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
			rsr a2, windowbase
			sub a0, a2, a0
			extui a0, a0, 0, 3

	.Lunrecoverable_fixup:
	l32i a2, a3, EXC_TABLE_DOUBLE_SAVE		l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
	xsr a0, depc		xsr a3, excsave1
			beqi a0, 1, .L1pane
			beqi a0, 3, .L3pane

	.Lunrecoverable:		rsr a0, depc
	rsr a3, excsave1		rotw -2
	wsr a0, excsave1
	movi a0, unrecoverable_exception		/*
	callx0 a0		* We are now in the user code's original window frame.
			* Process the exception as a user exception as if it was
			* taken by the user code.
			*
			* This is similar to the user exception vector,
			* except that PT_DEPC isn't set to EXCCAUSE.
			*/
			1:
			xsr a3, excsave1
			wsr a2, depc
			l32i a2, a3, EXC_TABLE_KSTK
			s32i a0, a2, PT_AREG0
			rsr a0, exccause

			s32i a0, a2, PT_DEPC

			addx4 a0, a0, a3
			l32i a0, a0, EXC_TABLE_FAST_USER
			xsr a3, excsave1
			jx a0

			.L1pane:
			rsr a0, depc
			rotw -1
			j 1b

			.L3pane:
			rsr a0, depc
			rotw -3
			j 1b

	.end literal_prefix		.end literal_prefix