xtensa: keep a3 and excsave1 on entry to exception handlers
Based on the SMP patch by Joe Taylor and subsequent fixes. Preserve exception table pointer (normally stored in excsave1 SR) as it cannot be easily restored in SMP environment. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>
This commit is contained in:
Max Filippov
Chris Zankel
parent
16c5becf39
commit
99d5040ebc
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@ -82,6 +82,7 @@
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#define PS_CALLINC_SHIFT 16
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#define PS_CALLINC_MASK 0x00030000
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#define PS_OWB_SHIFT 8
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#define PS_OWB_WIDTH 4
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#define PS_OWB_MASK 0x00000F00
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#define PS_RING_SHIFT 6
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#define PS_RING_MASK 0x000000C0
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@ -146,9 +146,9 @@
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* a0: trashed, original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original in DEPC
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* a3: dispatch table
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* a3: a3
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave_1: a3
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* excsave_1: dispatch table
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*
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* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
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* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
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@ -171,7 +171,6 @@ ENTRY(fast_unaligned)
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s32i a8, a2, PT_AREG8
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rsr a0, depc
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xsr a3, excsave1
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s32i a0, a2, PT_AREG2
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s32i a3, a2, PT_AREG3
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@ -32,9 +32,9 @@
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* a0: trashed, original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original in DEPC
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* a3: dispatch table
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* a3: a3
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave_1: a3
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* excsave_1: dispatch table
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*
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* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
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* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
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@ -225,9 +225,9 @@ ENDPROC(coprocessor_restore)
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* a0: trashed, original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original in DEPC
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* a3: dispatch table
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* a3: a3
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave_1: a3
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* excsave_1: dispatch table
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*
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* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
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* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
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@ -245,7 +245,6 @@ ENTRY(fast_coprocessor)
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/* Save remaining registers a1-a3 and SAR */
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xsr a3, excsave1
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s32i a3, a2, PT_AREG3
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rsr a3, sar
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s32i a1, a2, PT_AREG1
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@ -91,9 +91,9 @@
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* a0: trashed, original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original value in depc
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* a3: dispatch table
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* a3: a3
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave1: a3
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* excsave1: dispatch table
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*
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* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
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* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
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@ -109,9 +109,8 @@
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ENTRY(user_exception)
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/* Save a2, a3, and depc, restore excsave_1 and set SP. */
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/* Save a1, a2, a3, and set SP. */
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xsr a3, excsave1
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rsr a0, depc
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s32i a1, a2, PT_AREG1
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s32i a0, a2, PT_AREG2
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@ -237,9 +236,9 @@ ENDPROC(user_exception)
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* a0: trashed, original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original in DEPC
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* a3: dispatch table
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* a3: a3
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave_1: a3
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* excsave_1: dispatch table
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*
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* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
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* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
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@ -255,9 +254,8 @@ ENDPROC(user_exception)
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ENTRY(kernel_exception)
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/* Save a0, a2, a3, DEPC and set SP. */
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/* Save a1, a2, a3, and set SP. */
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xsr a3, excsave1 # restore a3, excsave_1
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rsr a0, depc # get a2
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s32i a1, a2, PT_AREG1
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s32i a0, a2, PT_AREG2
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@ -408,7 +406,7 @@ common_exception:
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* exception handler and call the exception handler.
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*/
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movi a4, exc_table
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rsr a4, excsave1
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mov a6, a1 # pass stack frame
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mov a7, a0 # pass EXCCAUSE
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addx4 a4, a0, a4
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@ -832,9 +830,9 @@ ENDPROC(unrecoverable_exception)
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* a0: trashed, original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original in DEPC
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* a3: dispatch table
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* a3: a3
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave_1: a3
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* excsave_1: dispatch table
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*
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* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
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* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
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@ -857,18 +855,16 @@ ENTRY(fast_alloca)
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rsr a0, depc # get a2
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s32i a4, a2, PT_AREG4 # save a4 and
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s32i a3, a2, PT_AREG3
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s32i a0, a2, PT_AREG2 # a2 to stack
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/* Exit critical section. */
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movi a0, 0
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rsr a3, excsave1
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s32i a0, a3, EXC_TABLE_FIXUP
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/* Restore a3, excsave_1 */
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xsr a3, excsave1 # make sure excsave_1 is valid for dbl.
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rsr a4, epc1 # get exception address
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s32i a3, a2, PT_AREG3 # save a3 to stack
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#ifdef ALLOCA_EXCEPTION_IN_IRAM
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#error iram not supported
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@ -1007,9 +1003,9 @@ ENDPROC(fast_alloca)
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* a0: trashed, original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original in DEPC
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* a3: dispatch table
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* a3: a3
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave_1: a3
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* excsave_1: dispatch table
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*/
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ENTRY(fast_syscall_kernel)
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@ -1056,7 +1052,6 @@ ENTRY(fast_syscall_unrecoverable)
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l32i a0, a2, PT_AREG0 # restore a0
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xsr a2, depc # restore a2, depc
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rsr a3, excsave1
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wsr a0, excsave1
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movi a0, unrecoverable_exception
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@ -1078,10 +1073,10 @@ ENDPROC(fast_syscall_unrecoverable)
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* a0: a2 (syscall-nr), original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original in a0 and DEPC
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* a3: dispatch table, original in excsave_1
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* a3: a3
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* a4..a15: unchanged
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave_1: a3
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* excsave_1: dispatch table
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*
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* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
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* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
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@ -1114,8 +1109,6 @@ ENDPROC(fast_syscall_unrecoverable)
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ENTRY(fast_syscall_xtensa)
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xsr a3, excsave1 # restore a3, excsave1
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s32i a7, a2, PT_AREG7 # we need an additional register
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movi a7, 4 # sizeof(unsigned int)
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access_ok a3, a7, a0, a2, .Leac # a0: scratch reg, a2: sp
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@ -1178,9 +1171,9 @@ ENDPROC(fast_syscall_xtensa)
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* a0: trashed, original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original in DEPC
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* a3: dispatch table
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* a3: a3
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave_1: a3
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* excsave_1: dispatch table
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*
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* Note: We assume the stack pointer is EXC_TABLE_KSTK in the fixup handler.
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*/
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@ -1189,15 +1182,16 @@ ENTRY(fast_syscall_spill_registers)
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/* Register a FIXUP handler (pass current wb as a parameter) */
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xsr a3, excsave1
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movi a0, fast_syscall_spill_registers_fixup
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s32i a0, a3, EXC_TABLE_FIXUP
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rsr a0, windowbase
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s32i a0, a3, EXC_TABLE_PARAM
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xsr a3, excsave1 # restore a3 and excsave_1
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/* Save a3 and SAR on stack. */
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/* Save a3, a4 and SAR on stack. */
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rsr a0, sar
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xsr a3, excsave1 # restore a3 and excsave_1
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s32i a3, a2, PT_AREG3
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s32i a4, a2, PT_AREG4
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s32i a0, a2, PT_AREG5 # store SAR to PT_AREG5
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@ -1251,14 +1245,14 @@ fast_syscall_spill_registers_fixup:
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* in WS, so that the exception handlers save them to the task stack.
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*/
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rsr a3, excsave1 # get spill-mask
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xsr a3, excsave1 # get spill-mask
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slli a2, a3, 1 # shift left by one
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slli a3, a2, 32-WSBITS
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src a2, a2, a3 # a1 = xxwww1yyxxxwww1yy......
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wsr a2, windowstart # set corrected windowstart
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movi a3, exc_table
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rsr a3, excsave1
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l32i a2, a3, EXC_TABLE_DOUBLE_SAVE # restore a2
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l32i a3, a3, EXC_TABLE_PARAM # original WB (in user task)
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@ -1295,7 +1289,7 @@ fast_syscall_spill_registers_fixup:
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/* Jump to the exception handler. */
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movi a3, exc_table
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rsr a3, excsave1
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rsr a0, exccause
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addx4 a0, a0, a3 # find entry in table
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l32i a0, a0, EXC_TABLE_FAST_USER # load handler
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@ -1312,6 +1306,7 @@ fast_syscall_spill_registers_fixup_return:
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xsr a3, excsave1
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movi a2, fast_syscall_spill_registers_fixup
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s32i a2, a3, EXC_TABLE_FIXUP
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s32i a0, a3, EXC_TABLE_DOUBLE_SAVE
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rsr a2, windowbase
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s32i a2, a3, EXC_TABLE_PARAM
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l32i a2, a3, EXC_TABLE_KSTK
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@ -1323,11 +1318,6 @@ fast_syscall_spill_registers_fixup_return:
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wsr a3, windowbase
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rsync
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/* Restore a3 and return. */
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movi a3, exc_table
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xsr a3, excsave1
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rfde
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@ -1514,9 +1504,8 @@ ENTRY(_spill_registers)
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movi a0, 0
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movi a3, exc_table
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rsr a3, excsave1
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l32i a1, a3, EXC_TABLE_KSTK
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wsr a3, excsave1
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movi a4, (1 << PS_WOE_BIT) | LOCKLEVEL
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wsr a4, ps
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@ -1560,9 +1549,9 @@ ENDPROC(fast_second_level_miss_double_kernel)
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* a0: trashed, original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original in DEPC
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* a3: dispatch table
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* a3: a3
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave_1: a3
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* excsave_1: dispatch table
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*
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* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
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* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
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@ -1570,9 +1559,10 @@ ENDPROC(fast_second_level_miss_double_kernel)
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ENTRY(fast_second_level_miss)
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/* Save a1. Note: we don't expect a double exception. */
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/* Save a1 and a3. Note: we don't expect a double exception. */
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s32i a1, a2, PT_AREG1
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s32i a3, a2, PT_AREG3
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/* We need to map the page of PTEs for the user task. Find
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* the pointer to that page. Also, it's possible for tsk->mm
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@ -1594,9 +1584,6 @@ ENTRY(fast_second_level_miss)
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l32i a0, a1, TASK_MM # tsk->mm
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beqz a0, 9f
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/* We deliberately destroy a3 that holds the exception table. */
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8: rsr a3, excvaddr # fault address
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_PGD_OFFSET(a0, a3, a1)
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l32i a0, a0, 0 # read pmdval
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@ -1647,7 +1634,7 @@ ENTRY(fast_second_level_miss)
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/* Exit critical section. */
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4: movi a3, exc_table # restore a3
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4: rsr a3, excsave1
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movi a0, 0
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s32i a0, a3, EXC_TABLE_FIXUP
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@ -1655,8 +1642,8 @@ ENTRY(fast_second_level_miss)
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l32i a0, a2, PT_AREG0
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l32i a1, a2, PT_AREG1
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l32i a3, a2, PT_AREG3
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l32i a2, a2, PT_DEPC
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xsr a3, excsave1
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bgeui a2, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f
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@ -1743,11 +1730,8 @@ ENTRY(fast_second_level_miss)
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2: /* Invalid PGD, default exception handling */
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movi a3, exc_table
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rsr a1, depc
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xsr a3, excsave1
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s32i a1, a2, PT_AREG2
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s32i a3, a2, PT_AREG3
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mov a1, a2
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rsr a2, ps
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@ -1767,9 +1751,9 @@ ENDPROC(fast_second_level_miss)
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* a0: trashed, original value saved on stack (PT_AREG0)
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* a1: a1
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* a2: new stack pointer, original in DEPC
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* a3: dispatch table
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* a3: a3
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* depc: a2, original value saved on stack (PT_DEPC)
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* excsave_1: a3
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* excsave_1: dispatch table
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*
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* PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
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* < VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
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@ -1777,17 +1761,17 @@ ENDPROC(fast_second_level_miss)
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ENTRY(fast_store_prohibited)
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/* Save a1 and a4. */
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/* Save a1 and a3. */
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s32i a1, a2, PT_AREG1
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s32i a4, a2, PT_AREG4
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s32i a3, a2, PT_AREG3
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GET_CURRENT(a1,a2)
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l32i a0, a1, TASK_MM # tsk->mm
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beqz a0, 9f
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8: rsr a1, excvaddr # fault address
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_PGD_OFFSET(a0, a1, a4)
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_PGD_OFFSET(a0, a1, a3)
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l32i a0, a0, 0
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beqz a0, 2f
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@ -1796,39 +1780,37 @@ ENTRY(fast_store_prohibited)
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* and is not PAGE_NONE. See pgtable.h for possible PTE layouts.
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*/
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_PTE_OFFSET(a0, a1, a4)
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l32i a4, a0, 0 # read pteval
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_PTE_OFFSET(a0, a1, a3)
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l32i a3, a0, 0 # read pteval
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movi a1, _PAGE_CA_INVALID
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ball a4, a1, 2f
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bbci.l a4, _PAGE_WRITABLE_BIT, 2f
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ball a3, a1, 2f
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bbci.l a3, _PAGE_WRITABLE_BIT, 2f
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movi a1, _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_HW_WRITE
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or a4, a4, a1
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or a3, a3, a1
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rsr a1, excvaddr
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s32i a4, a0, 0
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s32i a3, a0, 0
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/* We need to flush the cache if we have page coloring. */
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#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK
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dhwb a0, 0
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#endif
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pdtlb a0, a1
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wdtlb a4, a0
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wdtlb a3, a0
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/* Exit critical section. */
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movi a0, 0
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rsr a3, excsave1
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s32i a0, a3, EXC_TABLE_FIXUP
|
||||
|
||||
/* Restore the working registers, and return. */
|
||||
|
||||
l32i a4, a2, PT_AREG4
|
||||
l32i a3, a2, PT_AREG3
|
||||
l32i a1, a2, PT_AREG1
|
||||
l32i a0, a2, PT_AREG0
|
||||
l32i a2, a2, PT_DEPC
|
||||
|
||||
/* Restore excsave1 and a3. */
|
||||
|
||||
xsr a3, excsave1
|
||||
bgeui a2, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f
|
||||
|
||||
rsr a2, depc
|
||||
|
|
@ -1845,11 +1827,8 @@ ENTRY(fast_store_prohibited)
|
|||
|
||||
2: /* If there was a problem, handle fault in C */
|
||||
|
||||
rsr a4, depc # still holds a2
|
||||
xsr a3, excsave1
|
||||
s32i a4, a2, PT_AREG2
|
||||
s32i a3, a2, PT_AREG3
|
||||
l32i a4, a2, PT_AREG4
|
||||
rsr a3, depc # still holds a2
|
||||
s32i a3, a2, PT_AREG2
|
||||
mov a1, a2
|
||||
|
||||
rsr a2, ps
|
||||
|
|
|
|||
|
|
@ -78,6 +78,7 @@ ENTRY(_UserExceptionVector)
|
|||
s32i a0, a2, PT_DEPC # mark it as a regular exception
|
||||
addx4 a0, a0, a3 # find entry in table
|
||||
l32i a0, a0, EXC_TABLE_FAST_USER # load handler
|
||||
xsr a3, excsave1 # restore a3 and dispatch table
|
||||
jx a0
|
||||
|
||||
ENDPROC(_UserExceptionVector)
|
||||
|
|
@ -104,6 +105,7 @@ ENTRY(_KernelExceptionVector)
|
|||
s32i a0, a2, PT_DEPC # mark it as a regular exception
|
||||
addx4 a0, a0, a3 # find entry in table
|
||||
l32i a0, a0, EXC_TABLE_FAST_KERNEL # load handler address
|
||||
xsr a3, excsave1 # restore a3 and dispatch table
|
||||
jx a0
|
||||
|
||||
ENDPROC(_KernelExceptionVector)
|
||||
|
|
@ -168,7 +170,7 @@ ENDPROC(_KernelExceptionVector)
|
|||
*
|
||||
* a0: DEPC
|
||||
* a1: a1
|
||||
* a2: trashed, original value in EXC_TABLE_DOUBLE_A2
|
||||
* a2: trashed, original value in EXC_TABLE_DOUBLE_SAVE
|
||||
* a3: exctable
|
||||
* depc: a0
|
||||
* excsave_1: a3
|
||||
|
|
@ -204,47 +206,46 @@ ENDPROC(_KernelExceptionVector)
|
|||
|
||||
.section .DoubleExceptionVector.text, "ax"
|
||||
.begin literal_prefix .DoubleExceptionVector
|
||||
.globl _DoubleExceptionVector_WindowUnderflow
|
||||
.globl _DoubleExceptionVector_WindowOverflow
|
||||
|
||||
ENTRY(_DoubleExceptionVector)
|
||||
|
||||
/* Deliberately destroy excsave (don't assume it's value was valid). */
|
||||
|
||||
wsr a3, excsave1 # save a3
|
||||
xsr a3, excsave1
|
||||
s32i a2, a3, EXC_TABLE_DOUBLE_SAVE
|
||||
|
||||
/* Check for kernel double exception (usually fatal). */
|
||||
|
||||
rsr a3, ps
|
||||
_bbci.l a3, PS_UM_BIT, .Lksp
|
||||
rsr a2, ps
|
||||
_bbci.l a2, PS_UM_BIT, .Lksp
|
||||
|
||||
/* Check if we are currently handling a window exception. */
|
||||
/* Note: We don't need to indicate that we enter a critical section. */
|
||||
|
||||
xsr a0, depc # get DEPC, save a0
|
||||
|
||||
movi a3, WINDOW_VECTORS_VADDR
|
||||
_bltu a0, a3, .Lfixup
|
||||
addi a3, a3, WINDOW_VECTORS_SIZE
|
||||
_bgeu a0, a3, .Lfixup
|
||||
movi a2, WINDOW_VECTORS_VADDR
|
||||
_bltu a0, a2, .Lfixup
|
||||
addi a2, a2, WINDOW_VECTORS_SIZE
|
||||
_bgeu a0, a2, .Lfixup
|
||||
|
||||
/* Window overflow/underflow exception. Get stack pointer. */
|
||||
|
||||
mov a3, a2
|
||||
/* 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
|
||||
l32i a2, a3, EXC_TABLE_KSTK
|
||||
|
||||
/* 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
|
||||
* underflow exception. Therefore, we change window base to the value
|
||||
* before we entered the window underflow exception and prepare the
|
||||
|
|
@ -252,10 +253,11 @@ ENTRY(_DoubleExceptionVector)
|
|||
* by changing depc (in a0).
|
||||
* Note: We can trash the current window frame (a0...a3) and depc!
|
||||
*/
|
||||
|
||||
_DoubleExceptionVector_WindowUnderflow:
|
||||
xsr a3, excsave1
|
||||
wsr a2, depc # save stack pointer temporarily
|
||||
rsr a0, ps
|
||||
extui a0, a0, PS_OWB_SHIFT, 4
|
||||
extui a0, a0, PS_OWB_SHIFT, PS_OWB_WIDTH
|
||||
wsr a0, windowbase
|
||||
rsync
|
||||
|
||||
|
|
@ -263,52 +265,11 @@ ENTRY(_DoubleExceptionVector)
|
|||
|
||||
xsr a2, depc # save a2 and get stack pointer
|
||||
s32i a0, a2, PT_AREG0
|
||||
|
||||
wsr a3, excsave1 # save a3
|
||||
l32r a3, .Lexc_table
|
||||
|
||||
xsr a3, excsave1
|
||||
rsr a0, exccause
|
||||
s32i a0, a2, PT_DEPC # mark it as a regular exception
|
||||
addx4 a0, a0, a3
|
||||
l32i a0, a0, EXC_TABLE_FAST_USER
|
||||
jx a0
|
||||
|
||||
.Lfixup:/* Check for a fixup handler or if we were in a critical section. */
|
||||
|
||||
/* a0: depc, a1: a1, a2: a2, a3: trashed, depc: a0, excsave1: a3 */
|
||||
|
||||
l32r a3, .Lexc_table
|
||||
s32i a2, a3, EXC_TABLE_DOUBLE_SAVE # temporary variable
|
||||
|
||||
/* Enter critical section. */
|
||||
|
||||
l32i a2, a3, EXC_TABLE_FIXUP
|
||||
s32i a3, a3, EXC_TABLE_FIXUP
|
||||
beq a2, a3, .Lunrecoverable_fixup # critical!
|
||||
beqz a2, .Ldflt # no handler was registered
|
||||
|
||||
/* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave: a3 */
|
||||
|
||||
jx a2
|
||||
|
||||
.Ldflt: /* Get stack pointer. */
|
||||
|
||||
l32i a3, a3, EXC_TABLE_DOUBLE_SAVE
|
||||
addi a2, a3, -PT_USER_SIZE
|
||||
|
||||
.Lovfl: /* Jump to default handlers. */
|
||||
|
||||
/* a0: depc, a1: a1, a2: kstk, a3: a2, depc: a0, excsave: a3 */
|
||||
|
||||
xsr a3, depc
|
||||
s32i a0, a2, PT_DEPC
|
||||
s32i a3, a2, PT_AREG0
|
||||
|
||||
/* a0: avail, a1: a1, a2: kstk, a3: avail, depc: a2, excsave: a3 */
|
||||
|
||||
l32r a3, .Lexc_table
|
||||
rsr a0, exccause
|
||||
addx4 a0, a0, a3
|
||||
xsr a3, excsave1
|
||||
l32i a0, a0, EXC_TABLE_FAST_USER
|
||||
jx a0
|
||||
|
||||
|
|
@ -346,6 +307,163 @@ ENTRY(_DoubleExceptionVector)
|
|||
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. */
|
||||
|
||||
l32i a2, a3, EXC_TABLE_FIXUP
|
||||
s32i a3, a3, EXC_TABLE_FIXUP
|
||||
beq a2, a3, .Lunrecoverable_fixup # critical section
|
||||
beqz a2, .Ldflt # no handler was registered
|
||||
|
||||
/* a0: depc, a1: a1, a2: trash, a3: exctable, depc: a0, excsave: a3 */
|
||||
|
||||
jx a2
|
||||
|
||||
.Ldflt: /* Get stack pointer. */
|
||||
|
||||
l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
|
||||
addi a2, a2, -PT_USER_SIZE
|
||||
|
||||
/* a0: depc, a1: a1, a2: kstk, a3: exctable, depc: a0, excsave: a3 */
|
||||
|
||||
s32i a0, a2, PT_DEPC
|
||||
l32i a0, a3, EXC_TABLE_DOUBLE_SAVE
|
||||
xsr a0, depc
|
||||
s32i a0, a2, PT_AREG0
|
||||
|
||||
/* a0: avail, a1: a1, a2: kstk, a3: exctable, depc: a2, excsave: a3 */
|
||||
|
||||
rsr a0, exccause
|
||||
addx4 a0, a0, a3
|
||||
xsr a3, excsave1
|
||||
l32i a0, a0, EXC_TABLE_FAST_USER
|
||||
jx a0
|
||||
|
||||
/*
|
||||
* Restart window OVERFLOW 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
|
||||
* 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
|
||||
|
||||
addi a0, a0, -128
|
||||
bbsi a0, 8, 1f # don't restore except for overflow 8 and 12
|
||||
bbsi a0, 7, 2f
|
||||
|
||||
/*
|
||||
* 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).
|
||||
*/
|
||||
|
||||
l32e a2, a9, -16
|
||||
wsr a2, depc # replace the saved a0
|
||||
j 1f
|
||||
|
||||
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).
|
||||
*/
|
||||
|
||||
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
|
||||
|
||||
l32i a2, a3, EXC_TABLE_DOUBLE_SAVE
|
||||
xsr a3, excsave1
|
||||
beqi a0, 1, .L1pane
|
||||
beqi a0, 3, .L3pane
|
||||
|
||||
rsr a0, depc
|
||||
rotw -2
|
||||
|
||||
/*
|
||||
* 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
|
||||
|
||||
ENDPROC(_DoubleExceptionVector)
|
||||
|
|
|
|||
Loading…
Reference in New Issue