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csky: Remove prologue of page fault handler in entry.S
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There is a prologue on page fault handler which marking pages dirty
and/or accessed in page attributes, but all of these have been
handled in handle_pte_fault.

 - Add flush_tlb_one in vmalloc page fault instead of prologue.
 - Using cmxchg_fixup C codes in do_page_fault instead of ASM one.

Signed-off-by: Guo Ren <[email protected]>
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@guoren83
guoren83 committed Jan 12, 2021
1 parent 7b513cf commit b0ae5e2
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Showing 4 changed files with 48 additions and 131 deletions.
20 changes: 2 additions & 18 deletions arch/csky/kernel/atomic.S
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Original file line number Diff line number Diff line change
Expand Up @@ -40,11 +40,11 @@ ENTRY(csky_cmpxchg)
2:
sync.is
#else
1:
GLOBAL(csky_cmpxchg_ldw)
ldw a3, (a2)
cmpne a0, a3
bt16 3f
2:
GLOBAL(csky_cmpxchg_stw)
stw a1, (a2)
3:
#endif
Expand All @@ -59,19 +59,3 @@ ENTRY(csky_cmpxchg)
KSPTOUSP
rte
END(csky_cmpxchg)

#ifndef CONFIG_CPU_HAS_LDSTEX
/*
* Called from tlbmodified exception
*/
ENTRY(csky_cmpxchg_fixup)
mfcr a0, epc
lrw a1, 2b
cmpne a1, a0
bt 1f
subi a1, (2b - 1b)
stw a1, (sp, LSAVE_PC)
1:
rts
END(csky_cmpxchg_fixup)
#endif
104 changes: 2 additions & 102 deletions arch/csky/kernel/entry.S
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Original file line number Diff line number Diff line change
Expand Up @@ -13,10 +13,6 @@
#include <asm/page.h>
#include <asm/thread_info.h>

#define PTE_INDX_MSK 0xffc
#define PTE_INDX_SHIFT 10
#define _PGDIR_SHIFT 22

.macro zero_fp
#ifdef CONFIG_STACKTRACE
movi r8, 0
Expand All @@ -41,111 +37,15 @@
#endif
.endm

.macro tlbop_begin name, val0, val1, val2
ENTRY(csky_\name)
mtcr a3, ss2
mtcr r6, ss3
mtcr a2, ss4

RD_PGDR r6
RD_MEH a3
WR_MEH a3
#ifdef CONFIG_CPU_HAS_TLBI
tlbi.vaas a3
sync.is

btsti a3, 31
bf 1f
RD_PGDR_K r6
1:
#else
bgeni a2, 31
WR_MCIR a2
bgeni a2, 25
WR_MCIR a2
#endif
bclri r6, 0
lrw a2, PAGE_OFFSET
add r6, a2
lrw a2, va_pa_offset
ld.w a2, (a2, 0)
subu r6, a2

mov a2, a3
lsri a2, _PGDIR_SHIFT
lsli a2, 2
addu r6, a2
ldw r6, (r6)

lrw a2, PAGE_OFFSET
add r6, a2
lrw a2, va_pa_offset
ld.w a2, (a2, 0)
subu r6, a2

lsri a3, PTE_INDX_SHIFT
lrw a2, PTE_INDX_MSK
and a3, a2
addu r6, a3
ldw a3, (r6)

movi a2, (_PAGE_PRESENT | \val0)
and a3, a2
cmpne a3, a2
bt \name

/* First read/write the page, just update the flags */
ldw a3, (r6)
bgeni a2, PAGE_VALID_BIT
bseti a2, PAGE_ACCESSED_BIT
bseti a2, \val1
bseti a2, \val2
or a3, a2
stw a3, (r6)

/* Some cpu tlb-hardrefill bypass the cache */
#ifdef CONFIG_CPU_NEED_TLBSYNC
movi a2, 0x22
bseti a2, 6
mtcr r6, cr22
mtcr a2, cr17
sync
#endif

mfcr a3, ss2
mfcr r6, ss3
mfcr a2, ss4
rte
\name:
mfcr a3, ss2
mfcr r6, ss3
mfcr a2, ss4
.text
ENTRY(csky_pagefault)
SAVE_ALL 0
.endm
.macro tlbop_end is_write
zero_fp
context_tracking
RD_MEH a2
psrset ee, ie
mov a0, sp
movi a1, \is_write
jbsr do_page_fault
jmpi ret_from_exception
.endm

.text

tlbop_begin tlbinvalidl, _PAGE_READ, PAGE_VALID_BIT, PAGE_ACCESSED_BIT
tlbop_end 0

tlbop_begin tlbinvalids, _PAGE_WRITE, PAGE_DIRTY_BIT, PAGE_MODIFIED_BIT
tlbop_end 1

tlbop_begin tlbmodified, _PAGE_WRITE, PAGE_DIRTY_BIT, PAGE_MODIFIED_BIT
#ifndef CONFIG_CPU_HAS_LDSTEX
jbsr csky_cmpxchg_fixup
#endif
tlbop_end 1

ENTRY(csky_systemcall)
SAVE_ALL TRAP0_SIZE
Expand Down
10 changes: 4 additions & 6 deletions arch/csky/kernel/traps.c
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Original file line number Diff line number Diff line change
Expand Up @@ -39,9 +39,7 @@ asmlinkage void csky_cmpxchg(void);
asmlinkage void csky_get_tls(void);
asmlinkage void csky_irq(void);

asmlinkage void csky_tlbinvalidl(void);
asmlinkage void csky_tlbinvalids(void);
asmlinkage void csky_tlbmodified(void);
asmlinkage void csky_pagefault(void);

/* Defined in head.S */
asmlinkage void _start_smp_secondary(void);
Expand All @@ -66,9 +64,9 @@ void __init trap_init(void)
VEC_INIT(VEC_TRAP3, csky_get_tls);

/* setup MMU TLB exception */
VEC_INIT(VEC_TLBINVALIDL, csky_tlbinvalidl);
VEC_INIT(VEC_TLBINVALIDS, csky_tlbinvalids);
VEC_INIT(VEC_TLBMODIFIED, csky_tlbmodified);
VEC_INIT(VEC_TLBINVALIDL, csky_pagefault);
VEC_INIT(VEC_TLBINVALIDS, csky_pagefault);
VEC_INIT(VEC_TLBMODIFIED, csky_pagefault);

#ifdef CONFIG_CPU_HAS_FPU
init_fpu();
Expand Down
45 changes: 40 additions & 5 deletions arch/csky/mm/fault.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -39,20 +39,52 @@ int fixup_exception(struct pt_regs *regs)
return 0;
}

static inline bool is_write(struct pt_regs *regs)
{
switch (trap_no(regs)) {
case VEC_TLBINVALIDS:
return true;
case VEC_TLBMODIFIED:
return true;
}

return false;
}

#ifdef CONFIG_CPU_HAS_LDSTEX
static inline void csky_cmpxchg_fixup(struct pt_regs *regs)
{
return;
}
#else
extern unsigned long csky_cmpxchg_ldw;
extern unsigned long csky_cmpxchg_stw;
static inline void csky_cmpxchg_fixup(struct pt_regs *regs)
{
if (trap_no(regs) != VEC_TLBMODIFIED)
return;

if (instruction_pointer(regs) == csky_cmpxchg_stw)
instruction_pointer_set(regs, csky_cmpxchg_ldw);
return;
}
#endif

/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
* routines.
*/
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
unsigned long mmu_meh)
asmlinkage void do_page_fault(struct pt_regs *regs)
{
struct vm_area_struct *vma = NULL;
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
int si_code;
int fault;
unsigned long address = mmu_meh & PAGE_MASK;
unsigned long address = read_mmu_entryhi() & PAGE_MASK;

csky_cmpxchg_fixup(regs);

if (kprobe_page_fault(regs, tsk->thread.trap_no))
return;
Expand Down Expand Up @@ -104,6 +136,9 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
pte_k = pte_offset_kernel(pmd_k, address);
if (!pte_present(*pte_k))
goto no_context;

flush_tlb_one(address);

return;
}

Expand Down Expand Up @@ -132,7 +167,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
good_area:
si_code = SEGV_ACCERR;

if (write) {
if (is_write(regs)) {
if (!(vma->vm_flags & VM_WRITE))
goto bad_area;
} else {
Expand All @@ -145,7 +180,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
fault = handle_mm_fault(vma, address, write ? FAULT_FLAG_WRITE : 0,
fault = handle_mm_fault(vma, address, is_write(regs) ? FAULT_FLAG_WRITE : 0,
regs);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
Expand Down

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