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Diffstat (limited to 'arch/mips/kernel/smtc-asm.S')
| -rw-r--r-- | arch/mips/kernel/smtc-asm.S | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/arch/mips/kernel/smtc-asm.S b/arch/mips/kernel/smtc-asm.S new file mode 100644 index 00000000000000..c9d65196d91760 --- /dev/null +++ b/arch/mips/kernel/smtc-asm.S @@ -0,0 +1,130 @@ +/* + * Assembly Language Functions for MIPS MT SMTC support + */ + +/* + * This file should be built into the kernel only if CONFIG_MIPS_MT_SMTC is set. */ + +#include <asm/regdef.h> +#include <asm/asmmacro.h> +#include <asm/stackframe.h> +#include <asm/stackframe.h> + +/* + * "Software Interrupt" linkage. + * + * This is invoked when an "Interrupt" is sent from one TC to another, + * where the TC to be interrupted is halted, has it's Restart address + * and Status values saved by the "remote control" thread, then modified + * to cause execution to begin here, in kenel mode. This code then + * disguises the TC state as that of an exception and transfers + * control to the general exception or vectored interrupt handler. + */ + .set noreorder + +/* +The __smtc_ipi_vector would use k0 and k1 as temporaries and +1) Set EXL (this is per-VPE, so this can't be done by proxy!) +2) Restore the K/CU and IXMT bits to the pre "exception" state + (EXL means no interrupts and access to the kernel map). +3) Set EPC to be the saved value of TCRestart. +4) Jump to the exception handler entry point passed by the sender. + +CAN WE PROVE THAT WE WON'T DO THIS IF INTS DISABLED?? +*/ + +/* + * Reviled and slandered vision: Set EXL and restore K/CU/IXMT + * state of pre-halt thread, then save everything and call + * thought some function pointer to imaginary_exception, which + * will parse a register value or memory message queue to + * deliver things like interprocessor interrupts. On return + * from that function, jump to the global ret_from_irq code + * to invoke the scheduler and return as appropriate. + */ + +#define PT_PADSLOT4 (PT_R0-8) +#define PT_PADSLOT5 (PT_R0-4) + + .text + .align 5 +FEXPORT(__smtc_ipi_vector) + .set noat + /* Disable thread scheduling to make Status update atomic */ + DMT 27 # dmt k1 + ehb + /* Set EXL */ + mfc0 k0,CP0_STATUS + ori k0,k0,ST0_EXL + mtc0 k0,CP0_STATUS + ehb + /* Thread scheduling now inhibited by EXL. Restore TE state. */ + andi k1,k1,VPECONTROL_TE + beqz k1,1f + emt +1: + /* + * The IPI sender has put some information on the anticipated + * kernel stack frame. If we were in user mode, this will be + * built above the saved kernel SP. If we were already in the + * kernel, it will be built above the current CPU SP. + * + * Were we in kernel mode, as indicated by CU0? + */ + sll k1,k0,3 + .set noreorder + bltz k1,2f + move k1,sp + .set reorder + /* + * If previously in user mode, set CU0 and use kernel stack. + */ + li k1,ST0_CU0 + or k1,k1,k0 + mtc0 k1,CP0_STATUS + ehb + get_saved_sp + /* Interrupting TC will have pre-set values in slots in the new frame */ +2: subu k1,k1,PT_SIZE + /* Load TCStatus Value */ + lw k0,PT_TCSTATUS(k1) + /* Write it to TCStatus to restore CU/KSU/IXMT state */ + mtc0 k0,$2,1 + ehb + lw k0,PT_EPC(k1) + mtc0 k0,CP0_EPC + /* Save all will redundantly recompute the SP, but use it for now */ + SAVE_ALL + CLI + move a0,sp + /* Function to be invoked passed stack pad slot 5 */ + lw t0,PT_PADSLOT5(sp) + /* Argument from sender passed in stack pad slot 4 */ + lw a1,PT_PADSLOT4(sp) + jalr t0 + nop + j ret_from_irq + nop + +/* + * Called from idle loop to provoke processing of queued IPIs + * First IPI message in queue passed as argument. + */ + +LEAF(self_ipi) + /* Before anything else, block interrupts */ + mfc0 t0,CP0_TCSTATUS + ori t1,t0,TCSTATUS_IXMT + mtc0 t1,CP0_TCSTATUS + ehb + /* We know we're in kernel mode, so prepare stack frame */ + subu t1,sp,PT_SIZE + sw ra,PT_EPC(t1) + sw a0,PT_PADSLOT4(t1) + la t2,ipi_decode + sw t2,PT_PADSLOT5(t1) + /* Save pre-disable value of TCStatus */ + sw t0,PT_TCSTATUS(t1) + j __smtc_ipi_vector + nop +END(self_ipi) |