or1k: Allow exception nesting
Allow exceptions to be nested, which is especially useful with urgent
interrupts while processing an exception.
The implementation counts up the nesting level with each call to an
exception. In the outer exception (level 1), the exception stack is
started. All nested exceptions just reserve the redzone (scratch
memory that may be used by compiler) and exception context on the
stack, but then process on the same scratch.
Restriction: Impure pointers are shared among all exceptions. This may
be solved by creating an impure data structure in the stack frame with
each nested exception.
* or1k/crt0.S: Add exception nesting
* or1k/exceptions-asm.S: ditto
* or1k/util.c: ditto
This commit is contained in:
Jeff Johnston
parent
4098f69c43
commit
31cf34f849
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@ -1,3 +1,9 @@
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2015-08-07 Stefan Wallentowitz <stefan.wallentowitz@tum.de>
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* or1k/crt0.S: Add exception nesting
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* or1k/exceptions-asm.S: ditto
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* or1k/util.c: ditto
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2015-08-07 Stefan Wallentowitz <stefan.wallentowitz@tum.de>
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* or1k/sbrk.c: Make heap end globally visible
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@ -66,14 +66,18 @@
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// function
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#define EXCEPTION_STACK_FRAME 136
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#define REDZONE 128
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.extern _or1k_stack_top /* points to the next address after the stack */
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.extern _or1k_stack_bottom /* points to the last address in the stack */
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.extern _or1k_exception_stack_top
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.extern _or1k_exception_stack_bottom
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.extern _or1k_exception_level /* Nesting level of exceptions */
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.section .data
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.global _or1k_stack_size /* reserved stack size */
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.global _or1k_exception_stack_size
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.global _or1k_exception_level
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_or1k_stack_size: .word STACK_SIZE
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_or1k_exception_stack_size: .word EXCEPTION_STACK_SIZE
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@ -95,13 +99,35 @@ _or1k_exception_stack_size: .word EXCEPTION_STACK_SIZE
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#define GPR_BUF_OFFSET(x) (x << 2)
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#ifndef __OR1K_MULTICORE__
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#define CALL_EXCEPTION_HANDLER \
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/* store current stack pointer to address 4 */ \
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#define CALL_EXCEPTION_HANDLER(id) \
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/* Store current stack pointer to address 4 */ \
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l.sw 0x4(r0),r1; \
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/* Load address of exception nesting level */ \
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l.movhi r1,hi(_or1k_exception_level); \
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l.ori r1,r1,lo(_or1k_exception_level); \
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/* Load the current nesting level */ \
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l.lwz r1,0(r1); \
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/* Set flag if this is the outer (first) exception */ \
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l.sfeq r1,r0; \
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/* Branch to the code for nested exceptions */ \
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OR1K_DELAYED_NOP( \
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OR1K_INST(l.bnf .Lnested_##id) \
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); \
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/* Load top of the exception stack */ \
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l.movhi r1,hi(_or1k_exception_stack_top); \
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l.ori r1,r1,lo(_or1k_exception_stack_top); \
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l.lwz r1,0(r1); \
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OR1K_DELAYED( \
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/* Load value from array to stack pointer */ \
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OR1K_INST(l.lwz r1,0(r1)), \
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/* and jump over the nested code */ \
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OR1K_INST(l.j .Lnesting_done_##id) \
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); \
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.Lnested_##id: \
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/* Load back the stack pointer */ \
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l.lwz r1,0x4(r0)); \
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/* Add redzone, nesting needs this */ \
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l.addi r1,r1,-REDZONE; \
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.Lnesting_done_##id: \
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/* Reserve red zone and context space */ \
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l.addi r1,r1,-EXCEPTION_STACK_FRAME; \
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/* Store GPR3 in context */ \
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@ -112,6 +138,15 @@ _or1k_exception_stack_size: .word EXCEPTION_STACK_SIZE
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l.sw GPR_BUF_OFFSET(1)(r1),r3; \
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/* Store GPR4 in the context */ \
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l.sw GPR_BUF_OFFSET(4)(r1),r4; \
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/* Load address of the exception level */ \
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l.movhi r3,hi(_or1k_exception_level); \
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l.ori r3,r3,lo(_or1k_exception_level); \
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/* Load current value */ \
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l.lwz r4,0(r3); \
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/* Increment level */ \
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l.addi r4,r4,1; \
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/* Store back */ \
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l.sw 0(r3),r4; \
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/* Copy the current program counter as first */ \
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/* argument for the exception handler. This */ \
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/* is then used to determine the exception. */ \
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@ -124,11 +159,36 @@ _or1k_exception_stack_size: .word EXCEPTION_STACK_SIZE
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OR1K_INST(l.j _or1k_exception_handler) \
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)
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#else
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#define CALL_EXCEPTION_HANDLER \
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/* store current stack pointer to shadow reg */ \
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#define CALL_EXCEPTION_HANDLER(id) \
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/* Store current stack pointer to shadow reg */ \
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l.mtspr r0,r1,SHADOW_REG(1); \
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/* store current GPR3 as we need it */ \
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/* Store current GPR3 for temporary use */ \
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l.mtspr r0,r3,SHADOW_REG(2); \
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/* Store current GPR2 for the level pointer */ \
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l.mtspr r0,r4,SHADOW_REG(3); \
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/* Load nesting level of exceptions */ \
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l.movhi r4,hi(_or1k_exception_level); \
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l.ori r4,r4,lo(_or1k_exception_level); \
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/* Load array pointer */ \
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l.lwz r4,0(r4); \
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/* Get core id */ \
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l.mfspr r3,r0,OR1K_SPR_SYS_COREID_ADDR; \
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/* Generate offset */ \
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l.slli r3,r3,2; \
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/* Generate core nesting level address */ \
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l.add r4,r4,r3; \
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/* Load nesting level */ \
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l.lwz r3,0(r4); \
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/* Increment nesting level */ \
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l.addi r3,r3,1; \
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/* Write back nesting level */ \
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l.sw 0(r4),r3; \
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/* Set flag if this is the outer (first) exception */ \
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l.sfeqi r3,1; \
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/* Branch to the code for nested exceptions */ \
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OR1K_DELAYED_NOP( \
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OR1K_INST(l.bnf .Lnested_##id) \
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); \
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/* Load pointer to exception stack array */ \
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l.movhi r1,hi(_or1k_exception_stack_core); \
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l.ori r1,r1,lo(_or1k_exception_stack_core); \
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@ -137,10 +197,19 @@ _or1k_exception_stack_size: .word EXCEPTION_STACK_SIZE
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l.mfspr r3,r0,OR1K_SPR_SYS_COREID_ADDR; \
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/* Calculate offset in array */ \
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l.slli r3,r3,2; \
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/* Load value from array to stack pointer */ \
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l.add r1,r1,r3; \
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l.lwz r1,0(r1); \
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/* Reserve red zone and context space */ \
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OR1K_DELAYED( \
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/* Load value from array to stack pointer */ \
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OR1K_INST(l.lwz r1,0(r1)), \
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/* and jump over nested exception pointer */ \
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OR1K_INST(l.j .Lnesting_done_##id) \
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); \
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.Lnested_##id: \
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/* The stack pointer is still active */ \
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/* Add redzone, nesting needs this */ \
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l.addi r1,r1,-REDZONE; \
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.Lnesting_done_##id: \
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/* Reserve context space */ \
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l.addi r1,r1,-EXCEPTION_STACK_FRAME; \
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/* Load back software's stack pointer */ \
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l.mfspr r3,r0,SHADOW_REG(1); \
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@ -150,6 +219,8 @@ _or1k_exception_stack_size: .word EXCEPTION_STACK_SIZE
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l.mfspr r3,r0,SHADOW_REG(2); \
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/* Store this in the context */ \
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l.sw GPR_BUF_OFFSET(3)(r1),r3; \
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/* Load back GPR4 */ \
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l.mfspr r4,r0,SHADOW_REG(3); \
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/* Store GPR4 in the context */ \
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l.sw GPR_BUF_OFFSET(4)(r1),r4; \
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/* Copy the current program counter as first */ \
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@ -223,107 +294,107 @@ _or1k_reset:
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OR1K_DELAYED_NOP(OR1K_INST(l.jr r4))
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.org 0x200
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(2)
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/* 0x300: Data Page Fault exception */
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.org 0x300
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(3)
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/* 0x400: Insn Page Fault exception */
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.org 0x400
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(4)
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/* 0x500: Timer exception */
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.org 0x500
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(5)
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/* 0x600: Aligment exception */
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.org 0x600
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(6)
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/* 0x700: Illegal insn exception */
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.org 0x700
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(7)
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/* 0x800: External interrupt exception */
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.org 0x800
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(8)
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/* 0x900: DTLB miss exception */
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.org 0x900
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(9)
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/* 0xa00: ITLB miss exception */
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.org 0xa00
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(10)
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/* 0xb00: Range exception */
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.org 0xb00
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(11)
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/* 0xc00: Syscall exception */
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.org 0xc00
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(12)
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/* 0xd00: Floating point exception */
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.org 0xd00
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(13)
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/* 0xe00: Trap exception */
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.org 0xe00
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(14)
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/* 0xf00: Reserved exceptions */
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.org 0xf00
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(15)
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.org 0x1000
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(16)
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.org 0x1100
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(17)
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.org 0x1200
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(18)
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.org 0x1300
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(19)
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.org 0x1400
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(20)
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.org 0x1500
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(21)
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.org 0x1600
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(22)
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.org 0x1700
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(23)
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.org 0x1800
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(24)
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.org 0x1900
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(25)
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.org 0x1a00
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(26)
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.org 0x1b00
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(27)
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.org 0x1c00
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(28)
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.org 0x1d00
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(29)
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.org 0x1e00
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(30)
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.org 0x1f00
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CALL_EXCEPTION_HANDLER
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CALL_EXCEPTION_HANDLER(31)
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/* Pad to the end */
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.org 0x1ffc
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@ -27,6 +27,7 @@
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#define EXCEPTION_STACK_SIZE 136
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.extern _or1k_exception_handler_table
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.extern _or1k_exception_level
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/* -------------------------------------------------------------------------- */
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/*!Function to call appropriate exception handler
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@ -159,6 +160,24 @@ _or1k_exception_handler:
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#endif
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l.sw 0(r21),r20
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/* Decrement the exception nesting level */
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// Load the exception level entry
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l.movhi r2,hi(_or1k_exception_level)
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l.ori r2,r2,lo(_or1k_exception_level)
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#ifdef __OR1K_MULTICORE__
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// In multicore this is the pointer to an array
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// Load pointer value
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l.lwz r2,0(r2)
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// Add word offset of this core's nesting level
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l.add r2,r2,r22
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#endif
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// Load the nesting level entry
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l.lwz r3,0(r2)
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// Decrement nesting level
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l.addi r3,r3,-1
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// Store back the nesting level
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l.sw 0(r2),r3
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/* Restore state */
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l.lwz r2,0x80(r1)
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l.mtspr r0,r2,OR1K_SPR_SYS_EPCR_BASE
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@ -23,8 +23,13 @@
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#include "or1k-internals.h"
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#ifdef __OR1K_MULTICORE__
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// Define pointers to arrays
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uint32_t* *_or1k_stack_core;
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uint32_t* *_or1k_exception_stack_core;
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uint32_t* *_or1k_exception_level;
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#else
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// Define scalar
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uint32_t _or1k_exception_level;
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#endif
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uint32_t* _or1k_stack_top;
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@ -68,6 +73,15 @@ void _or1k_init() {
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#else
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_or1k_exception_handler_table[6] = _or1k_interrupt_handler;
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#endif
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#ifdef __OR1K_MULTICORE__
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_or1k_exception_level = _sbrk_r(0, 4 * or1k_numcores());
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for (c = 0; c < or1k_numcores(); c++) {
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_or1k_exception_level[c] = 0;
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}
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#else
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_or1k_exception_level = 0;
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#endif
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}
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uint32_t or1k_critical_begin() {
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