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linux/arch/tile/kernel/intvec_32.S
Chris Metcalf d6f0f22c3c arch/tile: update some comments to clarify register usage. 
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
2010-10-14 14:42:58 -04:00

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/*
* Copyright 2010 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*
* Linux interrupt vectors.
*/
#include <linux/linkage.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/unistd.h>
#include <asm/ptrace.h>
#include <asm/thread_info.h>
#include <asm/irqflags.h>
#include <asm/atomic.h>
#include <asm/asm-offsets.h>
#include <hv/hypervisor.h>
#include <arch/abi.h>
#include <arch/interrupts.h>
#include <arch/spr_def.h>
#ifdef CONFIG_PREEMPT
# error "No support for kernel preemption currently"
#endif
#if INT_INTCTRL_1 < 32 || INT_INTCTRL_1 >= 48
# error INT_INTCTRL_1 coded to set high interrupt mask
#endif
#define PTREGS_PTR(reg, ptreg) addli reg, sp, C_ABI_SAVE_AREA_SIZE + (ptreg)
#define PTREGS_OFFSET_SYSCALL PTREGS_OFFSET_REG(TREG_SYSCALL_NR)
#if !CHIP_HAS_WH64()
/* By making this an empty macro, we can use wh64 in the code. */
.macro wh64 reg
.endm
#endif
.macro push_reg reg, ptr=sp, delta=-4
{
sw \ptr, \reg
addli \ptr, \ptr, \delta
}
.endm
.macro pop_reg reg, ptr=sp, delta=4
{
lw \reg, \ptr
addli \ptr, \ptr, \delta
}
.endm
.macro pop_reg_zero reg, zreg, ptr=sp, delta=4
{
move \zreg, zero
lw \reg, \ptr
addi \ptr, \ptr, \delta
}
.endm
.macro push_extra_callee_saves reg
PTREGS_PTR(\reg, PTREGS_OFFSET_REG(51))
push_reg r51, \reg
push_reg r50, \reg
push_reg r49, \reg
push_reg r48, \reg
push_reg r47, \reg
push_reg r46, \reg
push_reg r45, \reg
push_reg r44, \reg
push_reg r43, \reg
push_reg r42, \reg
push_reg r41, \reg
push_reg r40, \reg
push_reg r39, \reg
push_reg r38, \reg
push_reg r37, \reg
push_reg r36, \reg
push_reg r35, \reg
push_reg r34, \reg, PTREGS_OFFSET_BASE - PTREGS_OFFSET_REG(34)
.endm
.macro panic str
.pushsection .rodata, "a"
1:
.asciz "\str"
.popsection
{
moveli r0, lo16(1b)
}
{
auli r0, r0, ha16(1b)
jal panic
}
.endm
#ifdef __COLLECT_LINKER_FEEDBACK__
.pushsection .text.intvec_feedback,"ax"
intvec_feedback:
.popsection
#endif
/*
* Default interrupt handler.
*
* vecnum is where we'll put this code.
* c_routine is the C routine we'll call.
*
* The C routine is passed two arguments:
* - A pointer to the pt_regs state.
* - The interrupt vector number.
*
* The "processing" argument specifies the code for processing
* the interrupt. Defaults to "handle_interrupt".
*/
.macro int_hand vecnum, vecname, c_routine, processing=handle_interrupt
.org (\vecnum << 8)
intvec_\vecname:
.ifc \vecnum, INT_SWINT_1
blz TREG_SYSCALL_NR_NAME, sys_cmpxchg
.endif
/* Temporarily save a register so we have somewhere to work. */
mtspr SYSTEM_SAVE_1_1, r0
mfspr r0, EX_CONTEXT_1_1
/* The cmpxchg code clears sp to force us to reset it here on fault. */
{
bz sp, 2f
andi r0, r0, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */
}
.ifc \vecnum, INT_DOUBLE_FAULT
/*
* For double-faults from user-space, fall through to the normal
* register save and stack setup path. Otherwise, it's the
* hypervisor giving us one last chance to dump diagnostics, and we
* branch to the kernel_double_fault routine to do so.
*/
bz r0, 1f
j _kernel_double_fault
1:
.else
/*
* If we're coming from user-space, then set sp to the top of
* the kernel stack. Otherwise, assume sp is already valid.
*/
{
bnz r0, 0f
move r0, sp
}
.endif
.ifc \c_routine, do_page_fault
/*
* The page_fault handler may be downcalled directly by the
* hypervisor even when Linux is running and has ICS set.
*
* In this case the contents of EX_CONTEXT_1_1 reflect the
* previous fault and can't be relied on to choose whether or
* not to reinitialize the stack pointer. So we add a test
* to see whether SYSTEM_SAVE_1_2 has the high bit set,
* and if so we don't reinitialize sp, since we must be coming
* from Linux. (In fact the precise case is !(val & ~1),
* but any Linux PC has to have the high bit set.)
*
* Note that the hypervisor *always* sets SYSTEM_SAVE_1_2 for
* any path that turns into a downcall to one of our TLB handlers.
*/
mfspr r0, SYSTEM_SAVE_1_2
{
blz r0, 0f /* high bit in S_S_1_2 is for a PC to use */
move r0, sp
}
.endif
2:
/*
* SYSTEM_SAVE_1_0 holds the cpu number in the low bits, and
* the current stack top in the higher bits. So we recover
* our stack top by just masking off the low bits, then
* point sp at the top aligned address on the actual stack page.
*/
mfspr r0, SYSTEM_SAVE_1_0
mm r0, r0, zero, LOG2_THREAD_SIZE, 31
0:
/*
* Align the stack mod 64 so we can properly predict what
* cache lines we need to write-hint to reduce memory fetch
* latency as we enter the kernel. The layout of memory is
* as follows, with cache line 0 at the lowest VA, and cache
* line 4 just below the r0 value this "andi" computes.
* Note that we never write to cache line 4, and we skip
* cache line 1 for syscalls.
*
* cache line 4: ptregs padding (two words)
* cache line 3: r46...lr, pc, ex1, faultnum, orig_r0, flags, pad
* cache line 2: r30...r45
* cache line 1: r14...r29
* cache line 0: 2 x frame, r0..r13
*/
andi r0, r0, -64
/*
* Push the first four registers on the stack, so that we can set
* them to vector-unique values before we jump to the common code.
*
* Registers are pushed on the stack as a struct pt_regs,
* with the sp initially just above the struct, and when we're
* done, sp points to the base of the struct, minus
* C_ABI_SAVE_AREA_SIZE, so we can directly jal to C code.
*
* This routine saves just the first four registers, plus the
* stack context so we can do proper backtracing right away,
* and defers to handle_interrupt to save the rest.
* The backtracer needs pc, ex1, lr, sp, r52, and faultnum.
*/
addli r0, r0, PTREGS_OFFSET_LR - (PTREGS_SIZE + KSTK_PTREGS_GAP)
wh64 r0 /* cache line 3 */
{
sw r0, lr
addli r0, r0, PTREGS_OFFSET_SP - PTREGS_OFFSET_LR
}
{
sw r0, sp
addli sp, r0, PTREGS_OFFSET_REG(52) - PTREGS_OFFSET_SP
}
{
sw sp, r52
addli sp, sp, PTREGS_OFFSET_REG(1) - PTREGS_OFFSET_REG(52)
}
wh64 sp /* cache line 0 */
{
sw sp, r1
addli sp, sp, PTREGS_OFFSET_REG(2) - PTREGS_OFFSET_REG(1)
}
{
sw sp, r2
addli sp, sp, PTREGS_OFFSET_REG(3) - PTREGS_OFFSET_REG(2)
}
{
sw sp, r3
addli sp, sp, PTREGS_OFFSET_PC - PTREGS_OFFSET_REG(3)
}
mfspr r0, EX_CONTEXT_1_0
.ifc \processing,handle_syscall
/*
* Bump the saved PC by one bundle so that when we return, we won't
* execute the same swint instruction again. We need to do this while
* we're in the critical section.
*/
addi r0, r0, 8
.endif
{
sw sp, r0
addli sp, sp, PTREGS_OFFSET_EX1 - PTREGS_OFFSET_PC
}
mfspr r0, EX_CONTEXT_1_1
{
sw sp, r0
addi sp, sp, PTREGS_OFFSET_FAULTNUM - PTREGS_OFFSET_EX1
/*
* Use r0 for syscalls so it's a temporary; use r1 for interrupts
* so that it gets passed through unchanged to the handler routine.
* Note that the .if conditional confusingly spans bundles.
*/
.ifc \processing,handle_syscall
movei r0, \vecnum
}
{
sw sp, r0
.else
movei r1, \vecnum
}
{
sw sp, r1
.endif
addli sp, sp, PTREGS_OFFSET_REG(0) - PTREGS_OFFSET_FAULTNUM
}
mfspr r0, SYSTEM_SAVE_1_1 /* Original r0 */
{
sw sp, r0
addi sp, sp, -PTREGS_OFFSET_REG(0) - 4
}
{
sw sp, zero /* write zero into "Next SP" frame pointer */
addi sp, sp, -4 /* leave SP pointing at bottom of frame */
}
.ifc \processing,handle_syscall
j handle_syscall
.else
/*
* Capture per-interrupt SPR context to registers.
* We overload the meaning of r3 on this path such that if its bit 31
* is set, we have to mask all interrupts including NMIs before
* clearing the interrupt critical section bit.
* See discussion below at "finish_interrupt_save".
*/
.ifc \c_routine, do_page_fault
mfspr r2, SYSTEM_SAVE_1_3 /* address of page fault */
mfspr r3, SYSTEM_SAVE_1_2 /* info about page fault */
.else
.ifc \vecnum, INT_DOUBLE_FAULT
{
mfspr r2, SYSTEM_SAVE_1_2 /* double fault info from HV */
movei r3, 0
}
.else
.ifc \c_routine, do_trap
{
mfspr r2, GPV_REASON
movei r3, 0
}
.else
.ifc \c_routine, op_handle_perf_interrupt
{
mfspr r2, PERF_COUNT_STS
movei r3, -1 /* not used, but set for consistency */
}
.else
#if CHIP_HAS_AUX_PERF_COUNTERS()
.ifc \c_routine, op_handle_aux_perf_interrupt
{
mfspr r2, AUX_PERF_COUNT_STS
movei r3, -1 /* not used, but set for consistency */
}
.else
#endif
movei r3, 0
#if CHIP_HAS_AUX_PERF_COUNTERS()
.endif
#endif
.endif
.endif
.endif
.endif
/* Put function pointer in r0 */
moveli r0, lo16(\c_routine)
{
auli r0, r0, ha16(\c_routine)
j \processing
}
.endif
ENDPROC(intvec_\vecname)
#ifdef __COLLECT_LINKER_FEEDBACK__
.pushsection .text.intvec_feedback,"ax"
.org (\vecnum << 5)
FEEDBACK_ENTER_EXPLICIT(intvec_\vecname, .intrpt1, 1 << 8)
jrp lr
.popsection
#endif
.endm
/*
* Save the rest of the registers that we didn't save in the actual
* vector itself. We can't use r0-r10 inclusive here.
*/
.macro finish_interrupt_save, function
/* If it's a syscall, save a proper orig_r0, otherwise just zero. */
PTREGS_PTR(r52, PTREGS_OFFSET_ORIG_R0)
{
.ifc \function,handle_syscall
sw r52, r0
.else
sw r52, zero
.endif
PTREGS_PTR(r52, PTREGS_OFFSET_TP)
}
/*
* For ordinary syscalls, we save neither caller- nor callee-
* save registers, since the syscall invoker doesn't expect the
* caller-saves to be saved, and the called kernel functions will
* take care of saving the callee-saves for us.
*
* For interrupts we save just the caller-save registers. Saving
* them is required (since the "caller" can't save them). Again,
* the called kernel functions will restore the callee-save
* registers for us appropriately.
*
* On return, we normally restore nothing special for syscalls,
* and just the caller-save registers for interrupts.
*
* However, there are some important caveats to all this:
*
* - We always save a few callee-save registers to give us
* some scratchpad registers to carry across function calls.
*
* - fork/vfork/etc require us to save all the callee-save
* registers, which we do in PTREGS_SYSCALL_ALL_REGS, below.
*
* - We always save r0..r5 and r10 for syscalls, since we need
* to reload them a bit later for the actual kernel call, and
* since we might need them for -ERESTARTNOINTR, etc.
*
* - Before invoking a signal handler, we save the unsaved
* callee-save registers so they are visible to the
* signal handler or any ptracer.
*
* - If the unsaved callee-save registers are modified, we set
* a bit in pt_regs so we know to reload them from pt_regs
* and not just rely on the kernel function unwinding.
* (Done for ptrace register writes and SA_SIGINFO handler.)
*/
{
sw r52, tp
PTREGS_PTR(r52, PTREGS_OFFSET_REG(33))
}
wh64 r52 /* cache line 2 */
push_reg r33, r52
push_reg r32, r52
push_reg r31, r52
.ifc \function,handle_syscall
push_reg r30, r52, PTREGS_OFFSET_SYSCALL - PTREGS_OFFSET_REG(30)
push_reg TREG_SYSCALL_NR_NAME, r52, \
PTREGS_OFFSET_REG(5) - PTREGS_OFFSET_SYSCALL
.else
push_reg r30, r52, PTREGS_OFFSET_REG(29) - PTREGS_OFFSET_REG(30)
wh64 r52 /* cache line 1 */
push_reg r29, r52
push_reg r28, r52
push_reg r27, r52
push_reg r26, r52
push_reg r25, r52
push_reg r24, r52
push_reg r23, r52
push_reg r22, r52
push_reg r21, r52
push_reg r20, r52
push_reg r19, r52
push_reg r18, r52
push_reg r17, r52
push_reg r16, r52
push_reg r15, r52
push_reg r14, r52
push_reg r13, r52
push_reg r12, r52
push_reg r11, r52
push_reg r10, r52
push_reg r9, r52
push_reg r8, r52
push_reg r7, r52
push_reg r6, r52
.endif
push_reg r5, r52
sw r52, r4
/* Load tp with our per-cpu offset. */
#ifdef CONFIG_SMP
{
mfspr r20, SYSTEM_SAVE_1_0
moveli r21, lo16(__per_cpu_offset)
}
{
auli r21, r21, ha16(__per_cpu_offset)
mm r20, r20, zero, 0, LOG2_THREAD_SIZE-1
}
s2a r20, r20, r21
lw tp, r20
#else
move tp, zero
#endif
/*
* If we will be returning to the kernel, we will need to
* reset the interrupt masks to the state they had before.
* Set DISABLE_IRQ in flags iff we came from PL1 with irqs disabled.
* We load flags in r32 here so we can jump to .Lrestore_regs
* directly after do_page_fault_ics() if necessary.
*/
mfspr r32, EX_CONTEXT_1_1
{
andi r32, r32, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */
PTREGS_PTR(r21, PTREGS_OFFSET_FLAGS)
}
bzt r32, 1f /* zero if from user space */
IRQS_DISABLED(r32) /* zero if irqs enabled */
#if PT_FLAGS_DISABLE_IRQ != 1
# error Value of IRQS_DISABLED used to set PT_FLAGS_DISABLE_IRQ; fix
#endif
1:
.ifnc \function,handle_syscall
/* Record the fact that we saved the caller-save registers above. */
ori r32, r32, PT_FLAGS_CALLER_SAVES
.endif
sw r21, r32
#ifdef __COLLECT_LINKER_FEEDBACK__
/*
* Notify the feedback routines that we were in the
* appropriate fixed interrupt vector area. Note that we
* still have ICS set at this point, so we can't invoke any
* atomic operations or we will panic. The feedback
* routines internally preserve r0..r10 and r30 up.
*/
.ifnc \function,handle_syscall
shli r20, r1, 5
.else
moveli r20, INT_SWINT_1 << 5
.endif
addli r20, r20, lo16(intvec_feedback)
auli r20, r20, ha16(intvec_feedback)
jalr r20
/* And now notify the feedback routines that we are here. */
FEEDBACK_ENTER(\function)
#endif
/*
* we've captured enough state to the stack (including in
* particular our EX_CONTEXT state) that we can now release
* the interrupt critical section and replace it with our
* standard "interrupts disabled" mask value. This allows
* synchronous interrupts (and profile interrupts) to punch
* through from this point onwards.
*
* If bit 31 of r3 is set during a non-NMI interrupt, we know we
* are on the path where the hypervisor has punched through our
* ICS with a page fault, so we call out to do_page_fault_ics()
* to figure out what to do with it. If the fault was in
* an atomic op, we unlock the atomic lock, adjust the
* saved register state a little, and return "zero" in r4,
* falling through into the normal page-fault interrupt code.
* If the fault was in a kernel-space atomic operation, then
* do_page_fault_ics() resolves it itself, returns "one" in r4,
* and as a result goes directly to restoring registers and iret,
* without trying to adjust the interrupt masks at all.
* The do_page_fault_ics() API involves passing and returning
* a five-word struct (in registers) to avoid writing the
* save and restore code here.
*/
.ifc \function,handle_nmi
IRQ_DISABLE_ALL(r20)
.else
.ifnc \function,handle_syscall
bgezt r3, 1f
{
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
jal do_page_fault_ics
}
FEEDBACK_REENTER(\function)
bzt r4, 1f
j .Lrestore_regs
1:
.endif
IRQ_DISABLE(r20, r21)
.endif
mtspr INTERRUPT_CRITICAL_SECTION, zero
#if CHIP_HAS_WH64()
/*
* Prepare the first 256 stack bytes to be rapidly accessible
* without having to fetch the background data. We don't really
* know how far to write-hint, but kernel stacks generally
* aren't that big, and write-hinting here does take some time.
*/
addi r52, sp, -64
{
wh64 r52
addi r52, r52, -64
}
{
wh64 r52
addi r52, r52, -64
}
{
wh64 r52
addi r52, r52, -64
}
wh64 r52
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
.ifnc \function,handle_nmi
/*
* We finally have enough state set up to notify the irq
* tracing code that irqs were disabled on entry to the handler.
* The TRACE_IRQS_OFF call clobbers registers r0-r29.
* For syscalls, we already have the register state saved away
* on the stack, so we don't bother to do any register saves here,
* and later we pop the registers back off the kernel stack.
* For interrupt handlers, save r0-r3 in callee-saved registers.
*/
.ifnc \function,handle_syscall
{ move r30, r0; move r31, r1 }
{ move r32, r2; move r33, r3 }
.endif
TRACE_IRQS_OFF
.ifnc \function,handle_syscall
{ move r0, r30; move r1, r31 }
{ move r2, r32; move r3, r33 }
.endif
.endif
#endif
.endm
.macro check_single_stepping, kind, not_single_stepping
/*
* Check for single stepping in user-level priv
* kind can be "normal", "ill", or "syscall"
* At end, if fall-thru
* r29: thread_info->step_state
* r28: &pt_regs->pc
* r27: pt_regs->pc
* r26: thread_info->step_state->buffer
*/
/* Check for single stepping */
GET_THREAD_INFO(r29)
{
/* Get pointer to field holding step state */
addi r29, r29, THREAD_INFO_STEP_STATE_OFFSET
/* Get pointer to EX1 in register state */
PTREGS_PTR(r27, PTREGS_OFFSET_EX1)
}
{
/* Get pointer to field holding PC */
PTREGS_PTR(r28, PTREGS_OFFSET_PC)
/* Load the pointer to the step state */
lw r29, r29
}
/* Load EX1 */
lw r27, r27
{
/* Points to flags */
addi r23, r29, SINGLESTEP_STATE_FLAGS_OFFSET
/* No single stepping if there is no step state structure */
bzt r29, \not_single_stepping
}
{
/* mask off ICS and any other high bits */
andi r27, r27, SPR_EX_CONTEXT_1_1__PL_MASK
/* Load pointer to single step instruction buffer */
lw r26, r29
}
/* Check priv state */
bnz r27, \not_single_stepping
/* Get flags */
lw r22, r23
{
/* Branch if single-step mode not enabled */
bbnst r22, \not_single_stepping
/* Clear enabled flag */
andi r22, r22, ~SINGLESTEP_STATE_MASK_IS_ENABLED
}
.ifc \kind,normal
{
/* Load PC */
lw r27, r28
/* Point to the entry containing the original PC */
addi r24, r29, SINGLESTEP_STATE_ORIG_PC_OFFSET
}
{
/* Disable single stepping flag */
sw r23, r22
}
{
/* Get the original pc */
lw r24, r24
/* See if the PC is at the start of the single step buffer */
seq r25, r26, r27
}
/*
* NOTE: it is really expected that the PC be in the single step buffer
* at this point
*/
bzt r25, \not_single_stepping
/* Restore the original PC */
sw r28, r24
.else
.ifc \kind,syscall
{
/* Load PC */
lw r27, r28
/* Point to the entry containing the next PC */
addi r24, r29, SINGLESTEP_STATE_NEXT_PC_OFFSET
}
{
/* Increment the stopped PC by the bundle size */
addi r26, r26, 8
/* Disable single stepping flag */
sw r23, r22
}
{
/* Get the next pc */
lw r24, r24
/*
* See if the PC is one bundle past the start of the
* single step buffer
*/
seq r25, r26, r27
}
{
/*
* NOTE: it is really expected that the PC be in the
* single step buffer at this point
*/
bzt r25, \not_single_stepping
}
/* Set to the next PC */
sw r28, r24
.else
{
/* Point to 3rd bundle in buffer */
addi r25, r26, 16
/* Load PC */
lw r27, r28
}
{
/* Disable single stepping flag */
sw r23, r22
/* See if the PC is in the single step buffer */
slte_u r24, r26, r27
}
{
slte_u r25, r27, r25
/*
* NOTE: it is really expected that the PC be in the
* single step buffer at this point
*/
bzt r24, \not_single_stepping
}
bzt r25, \not_single_stepping
.endif
.endif
.endm
/*
* Redispatch a downcall.
*/
.macro dc_dispatch vecnum, vecname
.org (\vecnum << 8)
intvec_\vecname:
j hv_downcall_dispatch
ENDPROC(intvec_\vecname)
.endm
/*
* Common code for most interrupts. The C function we're eventually
* going to is in r0, and the faultnum is in r1; the original
* values for those registers are on the stack.
*/
.pushsection .text.handle_interrupt,"ax"
handle_interrupt:
finish_interrupt_save handle_interrupt
/*
* Check for if we are single stepping in user level. If so, then
* we need to restore the PC.
*/
check_single_stepping normal, .Ldispatch_interrupt
.Ldispatch_interrupt:
/* Jump to the C routine; it should enable irqs as soon as possible. */
{
jalr r0
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
}
FEEDBACK_REENTER(handle_interrupt)
{
movei r30, 0 /* not an NMI */
j interrupt_return
}
STD_ENDPROC(handle_interrupt)
/*
* This routine takes a boolean in r30 indicating if this is an NMI.
* If so, we also expect a boolean in r31 indicating whether to
* re-enable the oprofile interrupts.
*/
STD_ENTRY(interrupt_return)
/* If we're resuming to kernel space, don't check thread flags. */
{
bnz r30, .Lrestore_all /* NMIs don't special-case user-space */
PTREGS_PTR(r29, PTREGS_OFFSET_EX1)
}
lw r29, r29
andi r29, r29, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */
{
bzt r29, .Lresume_userspace
PTREGS_PTR(r29, PTREGS_OFFSET_PC)
}
/* If we're resuming to _cpu_idle_nap, bump PC forward by 8. */
{
lw r28, r29
moveli r27, lo16(_cpu_idle_nap)
}
{
auli r27, r27, ha16(_cpu_idle_nap)
}
{
seq r27, r27, r28
}
{
bbns r27, .Lrestore_all
addi r28, r28, 8
}
sw r29, r28
j .Lrestore_all
.Lresume_userspace:
FEEDBACK_REENTER(interrupt_return)
/*
* Disable interrupts so as to make sure we don't
* miss an interrupt that sets any of the thread flags (like
* need_resched or sigpending) between sampling and the iret.
* Routines like schedule() or do_signal() may re-enable
* interrupts before returning.
*/
IRQ_DISABLE(r20, r21)
TRACE_IRQS_OFF /* Note: clobbers registers r0-r29 */
/* Get base of stack in r32; note r30/31 are used as arguments here. */
GET_THREAD_INFO(r32)
/* Check to see if there is any work to do before returning to user. */
{
addi r29, r32, THREAD_INFO_FLAGS_OFFSET
moveli r28, lo16(_TIF_ALLWORK_MASK)
}
{
lw r29, r29
auli r28, r28, ha16(_TIF_ALLWORK_MASK)
}
and r28, r29, r28
bnz r28, .Lwork_pending
/*
* In the NMI case we
* omit the call to single_process_check_nohz, which normally checks
* to see if we should start or stop the scheduler tick, because
* we can't call arbitrary Linux code from an NMI context.
* We always call the homecache TLB deferral code to re-trigger
* the deferral mechanism.
*
* The other chunk of responsibility this code has is to reset the
* interrupt masks appropriately to reset irqs and NMIs. We have
* to call TRACE_IRQS_OFF and TRACE_IRQS_ON to support all the
* lockdep-type stuff, but we can't set ICS until afterwards, since
* ICS can only be used in very tight chunks of code to avoid
* tripping over various assertions that it is off.
*
* (There is what looks like a window of vulnerability here since
* we might take a profile interrupt between the two SPR writes
* that set the mask, but since we write the low SPR word first,
* and our interrupt entry code checks the low SPR word, any
* profile interrupt will actually disable interrupts in both SPRs
* before returning, which is OK.)
*/
.Lrestore_all:
PTREGS_PTR(r0, PTREGS_OFFSET_EX1)
{
lw r0, r0
PTREGS_PTR(r32, PTREGS_OFFSET_FLAGS)
}
{
andi r0, r0, SPR_EX_CONTEXT_1_1__PL_MASK
lw r32, r32
}
bnz r0, 1f
j 2f
#if PT_FLAGS_DISABLE_IRQ != 1
# error Assuming PT_FLAGS_DISABLE_IRQ == 1 so we can use bbnst below
#endif
1: bbnst r32, 2f
IRQ_DISABLE(r20,r21)
TRACE_IRQS_OFF
movei r0, 1
mtspr INTERRUPT_CRITICAL_SECTION, r0
bzt r30, .Lrestore_regs
j 3f
2: TRACE_IRQS_ON
movei r0, 1
mtspr INTERRUPT_CRITICAL_SECTION, r0
IRQ_ENABLE(r20, r21)
bzt r30, .Lrestore_regs
3:
/*
* We now commit to returning from this interrupt, since we will be
* doing things like setting EX_CONTEXT SPRs and unwinding the stack
* frame. No calls should be made to any other code after this point.
* This code should only be entered with ICS set.
* r32 must still be set to ptregs.flags.
* We launch loads to each cache line separately first, so we can
* get some parallelism out of the memory subsystem.
* We start zeroing caller-saved registers throughout, since
* that will save some cycles if this turns out to be a syscall.
*/
.Lrestore_regs:
FEEDBACK_REENTER(interrupt_return) /* called from elsewhere */
/*
* Rotate so we have one high bit and one low bit to test.
* - low bit says whether to restore all the callee-saved registers,
* or just r30-r33, and r52 up.
* - high bit (i.e. sign bit) says whether to restore all the
* caller-saved registers, or just r0.
*/
#if PT_FLAGS_CALLER_SAVES != 2 || PT_FLAGS_RESTORE_REGS != 4
# error Rotate trick does not work :-)
#endif
{
rli r20, r32, 30
PTREGS_PTR(sp, PTREGS_OFFSET_REG(0))
}
/*
* Load cache lines 0, 2, and 3 in that order, then use
* the last loaded value, which makes it likely that the other
* cache lines have also loaded, at which point we should be
* able to safely read all the remaining words on those cache
* lines without waiting for the memory subsystem.
*/
pop_reg_zero r0, r28, sp, PTREGS_OFFSET_REG(30) - PTREGS_OFFSET_REG(0)
pop_reg_zero r30, r2, sp, PTREGS_OFFSET_PC - PTREGS_OFFSET_REG(30)
pop_reg_zero r21, r3, sp, PTREGS_OFFSET_EX1 - PTREGS_OFFSET_PC
pop_reg_zero lr, r4, sp, PTREGS_OFFSET_REG(52) - PTREGS_OFFSET_EX1
{
mtspr EX_CONTEXT_1_0, r21
move r5, zero
}
{
mtspr EX_CONTEXT_1_1, lr
andi lr, lr, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */
}
/* Restore callee-saveds that we actually use. */
pop_reg_zero r52, r6, sp, PTREGS_OFFSET_REG(31) - PTREGS_OFFSET_REG(52)
pop_reg_zero r31, r7
pop_reg_zero r32, r8
pop_reg_zero r33, r9, sp, PTREGS_OFFSET_REG(29) - PTREGS_OFFSET_REG(33)
/*
* If we modified other callee-saveds, restore them now.
* This is rare, but could be via ptrace or signal handler.
*/
{
move r10, zero
bbs r20, .Lrestore_callees
}
.Lcontinue_restore_regs:
/* Check if we're returning from a syscall. */
{
move r11, zero
blzt r20, 1f /* no, so go restore callee-save registers */
}
/*
* Check if we're returning to userspace.
* Note that if we're not, we don't worry about zeroing everything.
*/
{
addli sp, sp, PTREGS_OFFSET_LR - PTREGS_OFFSET_REG(29)
bnz lr, .Lkernel_return
}
/*
* On return from syscall, we've restored r0 from pt_regs, but we
* clear the remainder of the caller-saved registers. We could
* restore the syscall arguments, but there's not much point,
* and it ensures user programs aren't trying to use the
* caller-saves if we clear them, as well as avoiding leaking
* kernel pointers into userspace.
*/
pop_reg_zero lr, r12, sp, PTREGS_OFFSET_TP - PTREGS_OFFSET_LR
pop_reg_zero tp, r13, sp, PTREGS_OFFSET_SP - PTREGS_OFFSET_TP
{
lw sp, sp
move r14, zero
move r15, zero
}
{ move r16, zero; move r17, zero }
{ move r18, zero; move r19, zero }
{ move r20, zero; move r21, zero }
{ move r22, zero; move r23, zero }
{ move r24, zero; move r25, zero }
{ move r26, zero; move r27, zero }
/* Set r1 to errno if we are returning an error, otherwise zero. */
{
moveli r29, 1024
sub r1, zero, r0
}
slt_u r29, r1, r29
{
mnz r1, r29, r1
move r29, zero
}
iret
/*
* Not a syscall, so restore caller-saved registers.
* First kick off a load for cache line 1, which we're touching
* for the first time here.
*/
.align 64
1: pop_reg r29, sp, PTREGS_OFFSET_REG(1) - PTREGS_OFFSET_REG(29)
pop_reg r1
pop_reg r2
pop_reg r3
pop_reg r4
pop_reg r5
pop_reg r6
pop_reg r7
pop_reg r8
pop_reg r9
pop_reg r10
pop_reg r11
pop_reg r12
pop_reg r13
pop_reg r14
pop_reg r15
pop_reg r16
pop_reg r17
pop_reg r18
pop_reg r19
pop_reg r20
pop_reg r21
pop_reg r22
pop_reg r23
pop_reg r24
pop_reg r25
pop_reg r26
pop_reg r27
pop_reg r28, sp, PTREGS_OFFSET_LR - PTREGS_OFFSET_REG(28)
/* r29 already restored above */
bnz lr, .Lkernel_return
pop_reg lr, sp, PTREGS_OFFSET_TP - PTREGS_OFFSET_LR
pop_reg tp, sp, PTREGS_OFFSET_SP - PTREGS_OFFSET_TP
lw sp, sp
iret
/*
* We can't restore tp when in kernel mode, since a thread might
* have migrated from another cpu and brought a stale tp value.
*/
.Lkernel_return:
pop_reg lr, sp, PTREGS_OFFSET_SP - PTREGS_OFFSET_LR
lw sp, sp
iret
/* Restore callee-saved registers from r34 to r51. */
.Lrestore_callees:
addli sp, sp, PTREGS_OFFSET_REG(34) - PTREGS_OFFSET_REG(29)
pop_reg r34
pop_reg r35
pop_reg r36
pop_reg r37
pop_reg r38
pop_reg r39
pop_reg r40
pop_reg r41
pop_reg r42
pop_reg r43
pop_reg r44
pop_reg r45
pop_reg r46
pop_reg r47
pop_reg r48
pop_reg r49
pop_reg r50
pop_reg r51, sp, PTREGS_OFFSET_REG(29) - PTREGS_OFFSET_REG(51)
j .Lcontinue_restore_regs
.Lwork_pending:
/* Mask the reschedule flag */
andi r28, r29, _TIF_NEED_RESCHED
{
/*
* If the NEED_RESCHED flag is called, we call schedule(), which
* may drop this context right here and go do something else.
* On return, jump back to .Lresume_userspace and recheck.
*/
bz r28, .Lasync_tlb
/* Mask the async-tlb flag */
andi r28, r29, _TIF_ASYNC_TLB
}
jal schedule
FEEDBACK_REENTER(interrupt_return)
/* Reload the flags and check again */
j .Lresume_userspace
.Lasync_tlb:
{
bz r28, .Lneed_sigpending
/* Mask the sigpending flag */
andi r28, r29, _TIF_SIGPENDING
}
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
jal do_async_page_fault
FEEDBACK_REENTER(interrupt_return)
/*
* Go restart the "resume userspace" process. We may have
* fired a signal, and we need to disable interrupts again.
*/
j .Lresume_userspace
.Lneed_sigpending:
/*
* At this point we are either doing signal handling or single-step,
* so either way make sure we have all the registers saved.
*/
push_extra_callee_saves r0
{
/* If no signal pending, skip to singlestep check */
bz r28, .Lneed_singlestep
/* Mask the singlestep flag */
andi r28, r29, _TIF_SINGLESTEP
}
jal do_signal
FEEDBACK_REENTER(interrupt_return)
/* Reload the flags and check again */
j .Lresume_userspace
.Lneed_singlestep:
{
/* Get a pointer to the EX1 field */
PTREGS_PTR(r29, PTREGS_OFFSET_EX1)
/* If we get here, our bit must be set. */
bz r28, .Lwork_confusion
}
/* If we are in priv mode, don't single step */
lw r28, r29
andi r28, r28, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */
bnz r28, .Lrestore_all
/* Allow interrupts within the single step code */
TRACE_IRQS_ON /* Note: clobbers registers r0-r29 */
IRQ_ENABLE(r20, r21)
/* try to single-step the current instruction */
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
jal single_step_once
FEEDBACK_REENTER(interrupt_return)
/* Re-disable interrupts. TRACE_IRQS_OFF in .Lrestore_all. */
IRQ_DISABLE(r20,r21)
j .Lrestore_all
.Lwork_confusion:
move r0, r28
panic "thread_info allwork flags unhandled on userspace resume: %#x"
STD_ENDPROC(interrupt_return)
/*
* This interrupt variant clears the INT_INTCTRL_1 interrupt mask bit
* before returning, so we can properly get more downcalls.
*/
.pushsection .text.handle_interrupt_downcall,"ax"
handle_interrupt_downcall:
finish_interrupt_save handle_interrupt_downcall
check_single_stepping normal, .Ldispatch_downcall
.Ldispatch_downcall:
/* Clear INTCTRL_1 from the set of interrupts we ever enable. */
GET_INTERRUPTS_ENABLED_MASK_PTR(r30)
{
addi r30, r30, 4
movei r31, INT_MASK(INT_INTCTRL_1)
}
{
lw r20, r30
nor r21, r31, zero
}
and r20, r20, r21
sw r30, r20
{
jalr r0
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
}
FEEDBACK_REENTER(handle_interrupt_downcall)
/* Allow INTCTRL_1 to be enabled next time we enable interrupts. */
lw r20, r30
or r20, r20, r31
sw r30, r20
{
movei r30, 0 /* not an NMI */
j interrupt_return
}
STD_ENDPROC(handle_interrupt_downcall)
/*
* Some interrupts don't check for single stepping
*/
.pushsection .text.handle_interrupt_no_single_step,"ax"
handle_interrupt_no_single_step:
finish_interrupt_save handle_interrupt_no_single_step
{
jalr r0
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
}
FEEDBACK_REENTER(handle_interrupt_no_single_step)
{
movei r30, 0 /* not an NMI */
j interrupt_return
}
STD_ENDPROC(handle_interrupt_no_single_step)
/*
* "NMI" interrupts mask ALL interrupts before calling the
* handler, and don't check thread flags, etc., on the way
* back out. In general, the only things we do here for NMIs
* are the register save/restore, fixing the PC if we were
* doing single step, and the dataplane kernel-TLB management.
* We don't (for example) deal with start/stop of the sched tick.
*/
.pushsection .text.handle_nmi,"ax"
handle_nmi:
finish_interrupt_save handle_nmi
check_single_stepping normal, .Ldispatch_nmi
.Ldispatch_nmi:
{
jalr r0
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
}
FEEDBACK_REENTER(handle_nmi)
j interrupt_return
STD_ENDPROC(handle_nmi)
/*
* Parallel code for syscalls to handle_interrupt.
*/
.pushsection .text.handle_syscall,"ax"
handle_syscall:
finish_interrupt_save handle_syscall
/*
* Check for if we are single stepping in user level. If so, then
* we need to restore the PC.
*/
check_single_stepping syscall, .Ldispatch_syscall
.Ldispatch_syscall:
/* Enable irqs. */
TRACE_IRQS_ON
IRQ_ENABLE(r20, r21)
/* Bump the counter for syscalls made on this tile. */
moveli r20, lo16(irq_stat + IRQ_CPUSTAT_SYSCALL_COUNT_OFFSET)
auli r20, r20, ha16(irq_stat + IRQ_CPUSTAT_SYSCALL_COUNT_OFFSET)
add r20, r20, tp
lw r21, r20
addi r21, r21, 1
sw r20, r21
/* Trace syscalls, if requested. */
GET_THREAD_INFO(r31)
addi r31, r31, THREAD_INFO_FLAGS_OFFSET
lw r30, r31
andi r30, r30, _TIF_SYSCALL_TRACE
bzt r30, .Lrestore_syscall_regs
jal do_syscall_trace
FEEDBACK_REENTER(handle_syscall)
/*
* We always reload our registers from the stack at this
* point. They might be valid, if we didn't build with
* TRACE_IRQFLAGS, and this isn't a dataplane tile, and we're not
* doing syscall tracing, but there are enough cases now that it
* seems simplest just to do the reload unconditionally.
*/
.Lrestore_syscall_regs:
PTREGS_PTR(r11, PTREGS_OFFSET_REG(0))
pop_reg r0, r11
pop_reg r1, r11
pop_reg r2, r11
pop_reg r3, r11
pop_reg r4, r11
pop_reg r5, r11, PTREGS_OFFSET_SYSCALL - PTREGS_OFFSET_REG(5)
pop_reg TREG_SYSCALL_NR_NAME, r11
/* Ensure that the syscall number is within the legal range. */
moveli r21, __NR_syscalls
{
slt_u r21, TREG_SYSCALL_NR_NAME, r21
moveli r20, lo16(sys_call_table)
}
{
bbns r21, .Linvalid_syscall
auli r20, r20, ha16(sys_call_table)
}
s2a r20, TREG_SYSCALL_NR_NAME, r20
lw r20, r20
/* Jump to syscall handler. */
jalr r20; .Lhandle_syscall_link:
FEEDBACK_REENTER(handle_syscall)
/*
* Write our r0 onto the stack so it gets restored instead
* of whatever the user had there before.
*/
PTREGS_PTR(r29, PTREGS_OFFSET_REG(0))
sw r29, r0
/* Do syscall trace again, if requested. */
lw r30, r31
andi r30, r30, _TIF_SYSCALL_TRACE
bzt r30, 1f
jal do_syscall_trace
FEEDBACK_REENTER(handle_syscall)
1: j .Lresume_userspace /* jump into middle of interrupt_return */
.Linvalid_syscall:
/* Report an invalid syscall back to the user program */
{
PTREGS_PTR(r29, PTREGS_OFFSET_REG(0))
movei r28, -ENOSYS
}
sw r29, r28
j .Lresume_userspace /* jump into middle of interrupt_return */
STD_ENDPROC(handle_syscall)
/* Return the address for oprofile to suppress in backtraces. */
STD_ENTRY_SECTION(handle_syscall_link_address, .text.handle_syscall)
lnk r0
{
addli r0, r0, .Lhandle_syscall_link - .
jrp lr
}
STD_ENDPROC(handle_syscall_link_address)
STD_ENTRY(ret_from_fork)
jal sim_notify_fork
jal schedule_tail
FEEDBACK_REENTER(ret_from_fork)
j .Lresume_userspace /* jump into middle of interrupt_return */
STD_ENDPROC(ret_from_fork)
/*
* Code for ill interrupt.
*/
.pushsection .text.handle_ill,"ax"
handle_ill:
finish_interrupt_save handle_ill
/*
* Check for if we are single stepping in user level. If so, then
* we need to restore the PC.
*/
check_single_stepping ill, .Ldispatch_normal_ill
{
/* See if the PC is the 1st bundle in the buffer */
seq r25, r27, r26
/* Point to the 2nd bundle in the buffer */
addi r26, r26, 8
}
{
/* Point to the original pc */
addi r24, r29, SINGLESTEP_STATE_ORIG_PC_OFFSET
/* Branch if the PC is the 1st bundle in the buffer */
bnz r25, 3f
}
{
/* See if the PC is the 2nd bundle of the buffer */
seq r25, r27, r26
/* Set PC to next instruction */
addi r24, r29, SINGLESTEP_STATE_NEXT_PC_OFFSET
}
{
/* Point to flags */
addi r25, r29, SINGLESTEP_STATE_FLAGS_OFFSET
/* Branch if PC is in the second bundle */
bz r25, 2f
}
/* Load flags */
lw r25, r25
{
/*
* Get the offset for the register to restore
* Note: the lower bound is 2, so we have implicit scaling by 4.
* No multiplication of the register number by the size of a register
* is needed.
*/
mm r27, r25, zero, SINGLESTEP_STATE_TARGET_LB, \
SINGLESTEP_STATE_TARGET_UB
/* Mask Rewrite_LR */
andi r25, r25, SINGLESTEP_STATE_MASK_UPDATE
}
{
addi r29, r29, SINGLESTEP_STATE_UPDATE_VALUE_OFFSET
/* Don't rewrite temp register */
bz r25, 3f
}
{
/* Get the temp value */
lw r29, r29
/* Point to where the register is stored */
add r27, r27, sp
}
/* Add in the C ABI save area size to the register offset */
addi r27, r27, C_ABI_SAVE_AREA_SIZE
/* Restore the user's register with the temp value */
sw r27, r29
j 3f
2:
/* Must be in the third bundle */
addi r24, r29, SINGLESTEP_STATE_BRANCH_NEXT_PC_OFFSET
3:
/* set PC and continue */
lw r26, r24
sw r28, r26
/* Clear TIF_SINGLESTEP */
GET_THREAD_INFO(r0)
addi r1, r0, THREAD_INFO_FLAGS_OFFSET
{
lw r2, r1
addi r0, r0, THREAD_INFO_TASK_OFFSET /* currently a no-op */
}
andi r2, r2, ~_TIF_SINGLESTEP
sw r1, r2
/* Issue a sigtrap */
{
lw r0, r0 /* indirect thru thread_info to get task_info*/
addi r1, sp, C_ABI_SAVE_AREA_SIZE /* put ptregs pointer into r1 */
move r2, zero /* load error code into r2 */
}
jal send_sigtrap /* issue a SIGTRAP */
FEEDBACK_REENTER(handle_ill)
j .Lresume_userspace /* jump into middle of interrupt_return */
.Ldispatch_normal_ill:
{
jalr r0
PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
}
FEEDBACK_REENTER(handle_ill)
{
movei r30, 0 /* not an NMI */
j interrupt_return
}
STD_ENDPROC(handle_ill)
/* Various stub interrupt handlers and syscall handlers */
STD_ENTRY_LOCAL(_kernel_double_fault)
mfspr r1, EX_CONTEXT_1_0
move r2, lr
move r3, sp
move r4, r52
addi sp, sp, -C_ABI_SAVE_AREA_SIZE
j kernel_double_fault
STD_ENDPROC(_kernel_double_fault)
STD_ENTRY_LOCAL(bad_intr)
mfspr r2, EX_CONTEXT_1_0
panic "Unhandled interrupt %#x: PC %#lx"
STD_ENDPROC(bad_intr)
/* Put address of pt_regs in reg and jump. */
#define PTREGS_SYSCALL(x, reg) \
STD_ENTRY(_##x); \
{ \
PTREGS_PTR(reg, PTREGS_OFFSET_BASE); \
j x \
}; \
STD_ENDPROC(_##x)
PTREGS_SYSCALL(sys_execve, r3)
PTREGS_SYSCALL(sys_sigaltstack, r2)
PTREGS_SYSCALL(sys_rt_sigreturn, r0)
PTREGS_SYSCALL(sys_cmpxchg_badaddr, r1)
/* Save additional callee-saves to pt_regs, put address in r4 and jump. */
STD_ENTRY(_sys_clone)
push_extra_callee_saves r4
j sys_clone
STD_ENDPROC(_sys_clone)
/*
* This entrypoint is taken for the cmpxchg and atomic_update fast
* swints. We may wish to generalize it to other fast swints at some
* point, but for now there are just two very similar ones, which
* makes it faster.
*
* The fast swint code is designed to have a small footprint. It does
* not save or restore any GPRs, counting on the caller-save registers
* to be available to it on entry. It does not modify any callee-save
* registers (including "lr"). It does not check what PL it is being
* called at, so you'd better not call it other than at PL0.
* The <atomic.h> wrapper assumes it only clobbers r20-r29, so if
* it ever is necessary to use more registers, be aware.
*
* It does not use the stack, but since it might be re-interrupted by
* a page fault which would assume the stack was valid, it does
* save/restore the stack pointer and zero it out to make sure it gets reset.
* Since we always keep interrupts disabled, the hypervisor won't
* clobber our EX_CONTEXT_1_x registers, so we don't save/restore them
* (other than to advance the PC on return).
*
* We have to manually validate the user vs kernel address range
* (since at PL1 we can read/write both), and for performance reasons
* we don't allow cmpxchg on the fc000000 memory region, since we only
* validate that the user address is below PAGE_OFFSET.
*
* We place it in the __HEAD section to ensure it is relatively
* near to the intvec_SWINT_1 code (reachable by a conditional branch).
*
* Must match register usage in do_page_fault().
*/
__HEAD
.align 64
/* Align much later jump on the start of a cache line. */
#if !ATOMIC_LOCKS_FOUND_VIA_TABLE()
nop; nop
#endif
ENTRY(sys_cmpxchg)
/*
* Save "sp" and set it zero for any possible page fault.
*
* HACK: We want to both zero sp and check r0's alignment,
* so we do both at once. If "sp" becomes nonzero we
* know r0 is unaligned and branch to the error handler that
* restores sp, so this is OK.
*
* ICS is disabled right now so having a garbage but nonzero
* sp is OK, since we won't execute any faulting instructions
* when it is nonzero.
*/
{
move r27, sp
andi sp, r0, 3
}
/*
* Get the lock address in ATOMIC_LOCK_REG, and also validate that the
* address is less than PAGE_OFFSET, since that won't trap at PL1.
* We only use bits less than PAGE_SHIFT to avoid having to worry
* about aliasing among multiple mappings of the same physical page,
* and we ignore the low 3 bits so we have one lock that covers
* both a cmpxchg64() and a cmpxchg() on either its low or high word.
* NOTE: this code must match __atomic_hashed_lock() in lib/atomic.c.
*/
#if ATOMIC_LOCKS_FOUND_VIA_TABLE()
{
/* Check for unaligned input. */
bnz sp, .Lcmpxchg_badaddr
mm r25, r0, zero, 3, PAGE_SHIFT-1
}
{
crc32_32 r25, zero, r25
moveli r21, lo16(atomic_lock_ptr)
}
{
auli r21, r21, ha16(atomic_lock_ptr)
auli r23, zero, hi16(PAGE_OFFSET) /* hugepage-aligned */
}
{
shri r20, r25, 32 - ATOMIC_HASH_L1_SHIFT
slt_u r23, r0, r23
/*
* Ensure that the TLB is loaded before we take out the lock.
* On TILEPro, this will start fetching the value all the way
* into our L1 as well (and if it gets modified before we
* grab the lock, it will be invalidated from our cache
* before we reload it). On tile64, we'll start fetching it
* into our L1 if we're the home, and if we're not, we'll
* still at least start fetching it into the home's L2.
*/
lw r26, r0
}
{
s2a r21, r20, r21
bbns r23, .Lcmpxchg_badaddr
}
{
lw r21, r21
seqi r23, TREG_SYSCALL_NR_NAME, __NR_FAST_cmpxchg64
andi r25, r25, ATOMIC_HASH_L2_SIZE - 1
}
{
/* Branch away at this point if we're doing a 64-bit cmpxchg. */
bbs r23, .Lcmpxchg64
andi r23, r0, 7 /* Precompute alignment for cmpxchg64. */
}
{
/*
* We very carefully align the code that actually runs with
* the lock held (nine bundles) so that we know it is all in
* the icache when we start. This instruction (the jump) is
* at the start of the first cache line, address zero mod 64;
* we jump to somewhere in the second cache line to issue the
* tns, then jump back to finish up.
*/
s2a ATOMIC_LOCK_REG_NAME, r25, r21
j .Lcmpxchg32_tns
}
#else /* ATOMIC_LOCKS_FOUND_VIA_TABLE() */
{
/* Check for unaligned input. */
bnz sp, .Lcmpxchg_badaddr
auli r23, zero, hi16(PAGE_OFFSET) /* hugepage-aligned */
}
{
/*
* Slide bits into position for 'mm'. We want to ignore
* the low 3 bits of r0, and consider only the next
* ATOMIC_HASH_SHIFT bits.
* Because of C pointer arithmetic, we want to compute this:
*
* ((char*)atomic_locks +
* (((r0 >> 3) & (1 << (ATOMIC_HASH_SIZE - 1))) << 2))
*
* Instead of two shifts we just ">> 1", and use 'mm'
* to ignore the low and high bits we don't want.
*/
shri r25, r0, 1
slt_u r23, r0, r23
/*
* Ensure that the TLB is loaded before we take out the lock.
* On tilepro, this will start fetching the value all the way
* into our L1 as well (and if it gets modified before we
* grab the lock, it will be invalidated from our cache
* before we reload it). On tile64, we'll start fetching it
* into our L1 if we're the home, and if we're not, we'll
* still at least start fetching it into the home's L2.
*/
lw r26, r0
}
{
/* atomic_locks is page aligned so this suffices to get its addr. */
auli r21, zero, hi16(atomic_locks)
bbns r23, .Lcmpxchg_badaddr
}
{
/*
* Insert the hash bits into the page-aligned pointer.
* ATOMIC_HASH_SHIFT is so big that we don't actually hash
* the unmasked address bits, as that may cause unnecessary
* collisions.
*/
mm ATOMIC_LOCK_REG_NAME, r25, r21, 2, (ATOMIC_HASH_SHIFT + 2) - 1
seqi r23, TREG_SYSCALL_NR_NAME, __NR_FAST_cmpxchg64
}
{
/* Branch away at this point if we're doing a 64-bit cmpxchg. */
bbs r23, .Lcmpxchg64
andi r23, r0, 7 /* Precompute alignment for cmpxchg64. */
}
{
/*
* We very carefully align the code that actually runs with
* the lock held (nine bundles) so that we know it is all in
* the icache when we start. This instruction (the jump) is
* at the start of the first cache line, address zero mod 64;
* we jump to somewhere in the second cache line to issue the
* tns, then jump back to finish up.
*/
j .Lcmpxchg32_tns
}
#endif /* ATOMIC_LOCKS_FOUND_VIA_TABLE() */
ENTRY(__sys_cmpxchg_grab_lock)
/*
* Perform the actual cmpxchg or atomic_update.
* Note that __futex_mark_unlocked() in uClibc relies on
* atomic_update() to always perform an "mf", so don't make
* it optional or conditional without modifying that code.
*/
.Ldo_cmpxchg32:
{
lw r21, r0
seqi r23, TREG_SYSCALL_NR_NAME, __NR_FAST_atomic_update
move r24, r2
}
{
seq r22, r21, r1 /* See if cmpxchg matches. */
and r25, r21, r1 /* If atomic_update, compute (*mem & mask) */
}
{
or r22, r22, r23 /* Skip compare branch for atomic_update. */
add r25, r25, r2 /* Compute (*mem & mask) + addend. */
}
{
mvnz r24, r23, r25 /* Use atomic_update value if appropriate. */
bbns r22, .Lcmpxchg32_mismatch
}
sw r0, r24
/* Do slow mtspr here so the following "mf" waits less. */
{
move sp, r27
mtspr EX_CONTEXT_1_0, r28
}
mf
/* The following instruction is the start of the second cache line. */
{
move r0, r21
sw ATOMIC_LOCK_REG_NAME, zero
}
iret
/* Duplicated code here in the case where we don't overlap "mf" */
.Lcmpxchg32_mismatch:
{
move r0, r21
sw ATOMIC_LOCK_REG_NAME, zero
}
{
move sp, r27
mtspr EX_CONTEXT_1_0, r28
}
iret
/*
* The locking code is the same for 32-bit cmpxchg/atomic_update,
* and for 64-bit cmpxchg. We provide it as a macro and put
* it into both versions. We can't share the code literally
* since it depends on having the right branch-back address.
* Note that the first few instructions should share the cache
* line with the second half of the actual locked code.
*/
.macro cmpxchg_lock, bitwidth
/* Lock; if we succeed, jump back up to the read-modify-write. */
#ifdef CONFIG_SMP
tns r21, ATOMIC_LOCK_REG_NAME
#else
/*
* Non-SMP preserves all the lock infrastructure, to keep the
* code simpler for the interesting (SMP) case. However, we do
* one small optimization here and in atomic_asm.S, which is
* to fake out acquiring the actual lock in the atomic_lock table.
*/
movei r21, 0
#endif
/* Issue the slow SPR here while the tns result is in flight. */
mfspr r28, EX_CONTEXT_1_0
{
addi r28, r28, 8 /* return to the instruction after the swint1 */
bzt r21, .Ldo_cmpxchg\bitwidth
}
/*
* The preceding instruction is the last thing that must be
* on the second cache line.
*/
#ifdef CONFIG_SMP
/*
* We failed to acquire the tns lock on our first try. Now use
* bounded exponential backoff to retry, like __atomic_spinlock().
*/
{
moveli r23, 2048 /* maximum backoff time in cycles */
moveli r25, 32 /* starting backoff time in cycles */
}
1: mfspr r26, CYCLE_LOW /* get start point for this backoff */
2: mfspr r22, CYCLE_LOW /* test to see if we've backed off enough */
sub r22, r22, r26
slt r22, r22, r25
bbst r22, 2b
{
shli r25, r25, 1 /* double the backoff; retry the tns */
tns r21, ATOMIC_LOCK_REG_NAME
}
slt r26, r23, r25 /* is the proposed backoff too big? */
{
mvnz r25, r26, r23
bzt r21, .Ldo_cmpxchg\bitwidth
}
j 1b
#endif /* CONFIG_SMP */
.endm
.Lcmpxchg32_tns:
cmpxchg_lock 32
/*
* This code is invoked from sys_cmpxchg after most of the
* preconditions have been checked. We still need to check
* that r0 is 8-byte aligned, since if it's not we won't
* actually be atomic. However, ATOMIC_LOCK_REG has the atomic
* lock pointer and r27/r28 have the saved SP/PC.
* r23 is holding "r0 & 7" so we can test for alignment.
* The compare value is in r2/r3; the new value is in r4/r5.
* On return, we must put the old value in r0/r1.
*/
.align 64
.Lcmpxchg64:
{
#if ATOMIC_LOCKS_FOUND_VIA_TABLE()
s2a ATOMIC_LOCK_REG_NAME, r25, r21
#endif
bzt r23, .Lcmpxchg64_tns
}
j .Lcmpxchg_badaddr
.Ldo_cmpxchg64:
{
lw r21, r0
addi r25, r0, 4
}
{
lw r1, r25
}
seq r26, r21, r2
{
bz r26, .Lcmpxchg64_mismatch
seq r26, r1, r3
}
{
bz r26, .Lcmpxchg64_mismatch
}
sw r0, r4
sw r25, r5
/*
* The 32-bit path provides optimized "match" and "mismatch"
* iret paths, but we don't have enough bundles in this cache line
* to do that, so we just make even the "mismatch" path do an "mf".
*/
.Lcmpxchg64_mismatch:
{
move sp, r27
mtspr EX_CONTEXT_1_0, r28
}
mf
{
move r0, r21
sw ATOMIC_LOCK_REG_NAME, zero
}
iret
.Lcmpxchg64_tns:
cmpxchg_lock 64
/*
* Reset sp and revector to sys_cmpxchg_badaddr(), which will
* just raise the appropriate signal and exit. Doing it this
* way means we don't have to duplicate the code in intvec.S's
* int_hand macro that locates the top of the stack.
*/
.Lcmpxchg_badaddr:
{
moveli TREG_SYSCALL_NR_NAME, __NR_cmpxchg_badaddr
move sp, r27
}
j intvec_SWINT_1
ENDPROC(sys_cmpxchg)
ENTRY(__sys_cmpxchg_end)
/* The single-step support may need to read all the registers. */
int_unalign:
push_extra_callee_saves r0
j do_trap
/* Include .intrpt1 array of interrupt vectors */
.section ".intrpt1", "ax"
#define op_handle_perf_interrupt bad_intr
#define op_handle_aux_perf_interrupt bad_intr
#ifndef CONFIG_HARDWALL
#define do_hardwall_trap bad_intr
#endif
int_hand INT_ITLB_MISS, ITLB_MISS, \
do_page_fault, handle_interrupt_no_single_step
int_hand INT_MEM_ERROR, MEM_ERROR, bad_intr
int_hand INT_ILL, ILL, do_trap, handle_ill
int_hand INT_GPV, GPV, do_trap
int_hand INT_SN_ACCESS, SN_ACCESS, do_trap
int_hand INT_IDN_ACCESS, IDN_ACCESS, do_trap
int_hand INT_UDN_ACCESS, UDN_ACCESS, do_trap
int_hand INT_IDN_REFILL, IDN_REFILL, bad_intr
int_hand INT_UDN_REFILL, UDN_REFILL, bad_intr
int_hand INT_IDN_COMPLETE, IDN_COMPLETE, bad_intr
int_hand INT_UDN_COMPLETE, UDN_COMPLETE, bad_intr
int_hand INT_SWINT_3, SWINT_3, do_trap
int_hand INT_SWINT_2, SWINT_2, do_trap
int_hand INT_SWINT_1, SWINT_1, SYSCALL, handle_syscall
int_hand INT_SWINT_0, SWINT_0, do_trap
int_hand INT_UNALIGN_DATA, UNALIGN_DATA, int_unalign
int_hand INT_DTLB_MISS, DTLB_MISS, do_page_fault
int_hand INT_DTLB_ACCESS, DTLB_ACCESS, do_page_fault
int_hand INT_DMATLB_MISS, DMATLB_MISS, do_page_fault
int_hand INT_DMATLB_ACCESS, DMATLB_ACCESS, do_page_fault
int_hand INT_SNITLB_MISS, SNITLB_MISS, do_page_fault
int_hand INT_SN_NOTIFY, SN_NOTIFY, bad_intr
int_hand INT_SN_FIREWALL, SN_FIREWALL, do_hardwall_trap
int_hand INT_IDN_FIREWALL, IDN_FIREWALL, bad_intr
int_hand INT_UDN_FIREWALL, UDN_FIREWALL, do_hardwall_trap
int_hand INT_TILE_TIMER, TILE_TIMER, do_timer_interrupt
int_hand INT_IDN_TIMER, IDN_TIMER, bad_intr
int_hand INT_UDN_TIMER, UDN_TIMER, bad_intr
int_hand INT_DMA_NOTIFY, DMA_NOTIFY, bad_intr
int_hand INT_IDN_CA, IDN_CA, bad_intr
int_hand INT_UDN_CA, UDN_CA, bad_intr
int_hand INT_IDN_AVAIL, IDN_AVAIL, bad_intr
int_hand INT_UDN_AVAIL, UDN_AVAIL, bad_intr
int_hand INT_PERF_COUNT, PERF_COUNT, \
op_handle_perf_interrupt, handle_nmi
int_hand INT_INTCTRL_3, INTCTRL_3, bad_intr
int_hand INT_INTCTRL_2, INTCTRL_2, bad_intr
dc_dispatch INT_INTCTRL_1, INTCTRL_1
int_hand INT_INTCTRL_0, INTCTRL_0, bad_intr
int_hand INT_MESSAGE_RCV_DWNCL, MESSAGE_RCV_DWNCL, \
hv_message_intr, handle_interrupt_downcall
int_hand INT_DEV_INTR_DWNCL, DEV_INTR_DWNCL, \
tile_dev_intr, handle_interrupt_downcall
int_hand INT_I_ASID, I_ASID, bad_intr
int_hand INT_D_ASID, D_ASID, bad_intr
int_hand INT_DMATLB_MISS_DWNCL, DMATLB_MISS_DWNCL, \
do_page_fault, handle_interrupt_downcall
int_hand INT_SNITLB_MISS_DWNCL, SNITLB_MISS_DWNCL, \
do_page_fault, handle_interrupt_downcall
int_hand INT_DMATLB_ACCESS_DWNCL, DMATLB_ACCESS_DWNCL, \
do_page_fault, handle_interrupt_downcall
int_hand INT_SN_CPL, SN_CPL, bad_intr
int_hand INT_DOUBLE_FAULT, DOUBLE_FAULT, do_trap
#if CHIP_HAS_AUX_PERF_COUNTERS()
int_hand INT_AUX_PERF_COUNT, AUX_PERF_COUNT, \
op_handle_aux_perf_interrupt, handle_nmi
#endif
/* Synthetic interrupt delivered only by the simulator */
int_hand INT_BREAKPOINT, BREAKPOINT, do_breakpoint
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