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-rw-r--r--arch/parisc/kernel/asm-offsets.c1
-rw-r--r--arch/parisc/kernel/syscall.S383
2 files changed, 194 insertions, 190 deletions
diff --git a/arch/parisc/kernel/asm-offsets.c b/arch/parisc/kernel/asm-offsets.c
index 55c1c5189c6a..396aa3b47712 100644
--- a/arch/parisc/kernel/asm-offsets.c
+++ b/arch/parisc/kernel/asm-offsets.c
@@ -37,6 +37,7 @@ int main(void)
{
DEFINE(TASK_TI_FLAGS, offsetof(struct task_struct, thread_info.flags));
DEFINE(TASK_STACK, offsetof(struct task_struct, stack));
+ DEFINE(TASK_PAGEFAULT_DISABLED, offsetof(struct task_struct, pagefault_disabled));
BLANK();
DEFINE(TASK_REGS, offsetof(struct task_struct, thread.regs));
DEFINE(TASK_PT_PSW, offsetof(struct task_struct, thread.regs.gr[ 0]));
diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index 65c88ca7a7ac..027a43e1930d 100644
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -50,6 +50,22 @@ registers).
.level PA_ASM_LEVEL
+ .macro lws_pagefault_disable reg1,reg2
+ mfctl %cr30, \reg2
+ ldo TASK_PAGEFAULT_DISABLED(\reg2), \reg2
+ ldw 0(%sr2,\reg2), \reg1
+ ldo 1(\reg1), \reg1
+ stw \reg1, 0(%sr2,\reg2)
+ .endm
+
+ .macro lws_pagefault_enable reg1,reg2
+ mfctl %cr30, \reg2
+ ldo TASK_PAGEFAULT_DISABLED(\reg2), \reg2
+ ldw 0(%sr2,\reg2), \reg1
+ ldo -1(\reg1), \reg1
+ stw \reg1, 0(%sr2,\reg2)
+ .endm
+
.text
.import syscall_exit,code
@@ -490,8 +506,34 @@ lws_start:
/* Jump to lws, lws table pointers already relocated */
be,n 0(%sr2,%r21)
+lws_exit_noerror:
+ lws_pagefault_enable %r1,%r21
+ stw,ma %r20, 0(%sr2,%r20)
+ ssm PSW_SM_I, %r0
+ b lws_exit
+ copy %r0, %r21
+
+lws_wouldblock:
+ ssm PSW_SM_I, %r0
+ ldo 2(%r0), %r28
+ b lws_exit
+ ldo -EAGAIN(%r0), %r21
+
+lws_pagefault:
+ lws_pagefault_enable %r1,%r21
+ stw,ma %r20, 0(%sr2,%r20)
+ ssm PSW_SM_I, %r0
+ ldo 3(%r0),%r28
+ b lws_exit
+ ldo -EAGAIN(%r0),%r21
+
+lws_fault:
+ ldo 1(%r0),%r28
+ b lws_exit
+ ldo -EFAULT(%r0),%r21
+
lws_exit_nosys:
- ldo -ENOSYS(%r0),%r21 /* set errno */
+ ldo -ENOSYS(%r0),%r21
/* Fall through: Return to userspace */
lws_exit:
@@ -518,27 +560,19 @@ lws_exit:
%r28 - Return prev through this register.
%r21 - Kernel error code
- If debugging is DISabled:
-
- %r21 has the following meanings:
-
+ %r21 returns the following error codes:
EAGAIN - CAS is busy, ldcw failed, try again.
EFAULT - Read or write failed.
- If debugging is enabled:
-
- EDEADLOCK - CAS called recursively.
- EAGAIN && r28 == 1 - CAS is busy. Lock contended.
- EAGAIN && r28 == 2 - CAS is busy. ldcw failed.
- EFAULT - Read or write failed.
+ If EAGAIN is returned, %r28 indicates the busy reason:
+ r28 == 1 - CAS is busy. lock contended.
+ r28 == 2 - CAS is busy. ldcw failed.
+ r28 == 3 - CAS is busy. page fault.
Scratch: r20, r28, r1
****************************************************/
- /* Do not enable LWS debugging */
-#define ENABLE_LWS_DEBUG 0
-
/* ELF64 Process entry path */
lws_compare_and_swap64:
#ifdef CONFIG_64BIT
@@ -551,59 +585,45 @@ lws_compare_and_swap64:
b,n lws_exit_nosys
#endif
- /* ELF32 Process entry path */
+ /* ELF32/ELF64 Process entry path */
lws_compare_and_swap32:
#ifdef CONFIG_64BIT
- /* Clip all the input registers */
+ /* Wide mode user process? */
+ bb,<,n %sp, 31, lws_compare_and_swap
+
+ /* Clip all the input registers for 32-bit processes */
depdi 0, 31, 32, %r26
depdi 0, 31, 32, %r25
depdi 0, 31, 32, %r24
#endif
lws_compare_and_swap:
- /* Load start of lock table */
- ldil L%lws_lock_start, %r20
- ldo R%lws_lock_start(%r20), %r28
+ /* Trigger memory reference interruptions without writing to memory */
+1: ldw 0(%r26), %r28
+2: stbys,e %r0, 0(%r26)
+
+ /* Calculate 8-bit hash index from virtual address */
+ extru_safe %r26, 27, 8, %r20
- /* Extract eight bits from r26 and hash lock (Bits 3-11) */
- extru_safe %r26, 28, 8, %r20
+ /* Load start of lock table */
+ ldil L%lws_lock_start, %r28
+ ldo R%lws_lock_start(%r28), %r28
- /* Find lock to use, the hash is either one of 0 to
- 15, multiplied by 16 (keep it 16-byte aligned)
+ /* Find lock to use, the hash index is one of 0 to
+ 255, multiplied by 16 (keep it 16-byte aligned)
and add to the lock table offset. */
shlw %r20, 4, %r20
add %r20, %r28, %r20
-# if ENABLE_LWS_DEBUG
- /*
- DEBUG, check for deadlock!
- If the thread register values are the same
- then we were the one that locked it last and
- this is a recurisve call that will deadlock.
- We *must* giveup this call and fail.
- */
- ldw 4(%sr2,%r20), %r28 /* Load thread register */
- /* WARNING: If cr27 cycles to the same value we have problems */
- mfctl %cr27, %r21 /* Get current thread register */
- cmpb,<>,n %r21, %r28, cas_lock /* Called recursive? */
- b lws_exit /* Return error! */
- ldo -EDEADLOCK(%r0), %r21
-cas_lock:
- cmpb,=,n %r0, %r28, cas_nocontend /* Is nobody using it? */
- ldo 1(%r0), %r28 /* 1st case */
- b lws_exit /* Contended... */
- ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
-cas_nocontend:
-# endif
-/* ENABLE_LWS_DEBUG */
-
- /* COW breaks can cause contention on UP systems */
- LDCW 0(%sr2,%r20), %r28 /* Try to acquire the lock */
- cmpb,<>,n %r0, %r28, cas_action /* Did we get it? */
-cas_wouldblock:
- ldo 2(%r0), %r28 /* 2nd case */
- b lws_exit /* Contended... */
- ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
+ rsm PSW_SM_I, %r0 /* Disable interrupts */
+
+ /* Try to acquire the lock */
+ LDCW 0(%sr2,%r20), %r28
+ comclr,<> %r0, %r28, %r0
+ b,n lws_wouldblock
+
+ /* Disable page faults to prevent sleeping in critical region */
+ lws_pagefault_disable %r21,%r28
/*
prev = *addr;
@@ -613,59 +633,35 @@ cas_wouldblock:
*/
/* NOTES:
- This all works becuse intr_do_signal
+ This all works because intr_do_signal
and schedule both check the return iasq
and see that we are on the kernel page
so this process is never scheduled off
or is ever sent any signal of any sort,
- thus it is wholly atomic from usrspaces
+ thus it is wholly atomic from usrspace's
perspective
*/
-cas_action:
-#if defined CONFIG_SMP && ENABLE_LWS_DEBUG
- /* DEBUG */
- mfctl %cr27, %r1
- stw %r1, 4(%sr2,%r20)
-#endif
/* The load and store could fail */
-1: ldw 0(%r26), %r28
+3: ldw 0(%r26), %r28
sub,<> %r28, %r25, %r0
-2: stw %r24, 0(%r26)
- /* Free lock */
- stw,ma %r20, 0(%sr2,%r20)
-#if ENABLE_LWS_DEBUG
- /* Clear thread register indicator */
- stw %r0, 4(%sr2,%r20)
-#endif
- /* Return to userspace, set no error */
- b lws_exit
- copy %r0, %r21
+4: stw %r24, 0(%r26)
+ b,n lws_exit_noerror
-3:
- /* Error occurred on load or store */
- /* Free lock */
- stw,ma %r20, 0(%sr2,%r20)
-#if ENABLE_LWS_DEBUG
- stw %r0, 4(%sr2,%r20)
-#endif
- b lws_exit
- ldo -EFAULT(%r0),%r21 /* set errno */
- nop
- nop
- nop
- nop
+ /* A fault occurred on load or stbys,e store */
+5: b,n lws_fault
+ ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 5b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 5b-linux_gateway_page)
- /* Two exception table entries, one for the load,
- the other for the store. Either return -EFAULT.
- Each of the entries must be relocated. */
- ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 3b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 3b-linux_gateway_page)
+ /* A page fault occurred in critical region */
+6: b,n lws_pagefault
+ ASM_EXCEPTIONTABLE_ENTRY(3b-linux_gateway_page, 6b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 6b-linux_gateway_page)
/***************************************************
New CAS implementation which uses pointers and variable size
information. The value pointed by old and new MUST NOT change
- while performing CAS. The lock only protect the value at %r26.
+ while performing CAS. The lock only protects the value at %r26.
%r26 - Address to examine
%r25 - Pointer to the value to check (old)
@@ -674,25 +670,32 @@ cas_action:
%r28 - Return non-zero on failure
%r21 - Kernel error code
- %r21 has the following meanings:
-
+ %r21 returns the following error codes:
EAGAIN - CAS is busy, ldcw failed, try again.
EFAULT - Read or write failed.
+ If EAGAIN is returned, %r28 indicates the busy reason:
+ r28 == 1 - CAS is busy. lock contended.
+ r28 == 2 - CAS is busy. ldcw failed.
+ r28 == 3 - CAS is busy. page fault.
+
Scratch: r20, r22, r28, r29, r1, fr4 (32bit for 64bit CAS only)
****************************************************/
- /* ELF32 Process entry path */
lws_compare_and_swap_2:
#ifdef CONFIG_64BIT
- /* Clip the input registers. We don't need to clip %r23 as we
- only use it for word operations */
+ /* Wide mode user process? */
+ bb,<,n %sp, 31, cas2_begin
+
+ /* Clip the input registers for 32-bit processes. We don't
+ need to clip %r23 as we only use it for word operations */
depdi 0, 31, 32, %r26
depdi 0, 31, 32, %r25
depdi 0, 31, 32, %r24
#endif
+cas2_begin:
/* Check the validity of the size pointer */
subi,>>= 3, %r23, %r0
b,n lws_exit_nosys
@@ -703,69 +706,77 @@ lws_compare_and_swap_2:
blr %r29, %r0
nop
- /* 8bit load */
-4: ldb 0(%r25), %r25
+ /* 8-bit load */
+1: ldb 0(%r25), %r25
b cas2_lock_start
-5: ldb 0(%r24), %r24
+2: ldb 0(%r24), %r24
nop
nop
nop
nop
nop
- /* 16bit load */
-6: ldh 0(%r25), %r25
+ /* 16-bit load */
+3: ldh 0(%r25), %r25
b cas2_lock_start
-7: ldh 0(%r24), %r24
+4: ldh 0(%r24), %r24
nop
nop
nop
nop
nop
- /* 32bit load */
-8: ldw 0(%r25), %r25
+ /* 32-bit load */
+5: ldw 0(%r25), %r25
b cas2_lock_start
-9: ldw 0(%r24), %r24
+6: ldw 0(%r24), %r24
nop
nop
nop
nop
nop
- /* 64bit load */
+ /* 64-bit load */
#ifdef CONFIG_64BIT
-10: ldd 0(%r25), %r25
-11: ldd 0(%r24), %r24
+7: ldd 0(%r25), %r25
+8: ldd 0(%r24), %r24
#else
/* Load old value into r22/r23 - high/low */
-10: ldw 0(%r25), %r22
-11: ldw 4(%r25), %r23
+7: ldw 0(%r25), %r22
+8: ldw 4(%r25), %r23
/* Load new value into fr4 for atomic store later */
-12: flddx 0(%r24), %fr4
+9: flddx 0(%r24), %fr4
#endif
cas2_lock_start:
- /* Load start of lock table */
- ldil L%lws_lock_start, %r20
- ldo R%lws_lock_start(%r20), %r28
+ /* Trigger memory reference interruptions without writing to memory */
+ copy %r26, %r28
+ depi_safe 0, 31, 2, %r28
+10: ldw 0(%r28), %r1
+11: stbys,e %r0, 0(%r28)
- /* Extract eight bits from r26 and hash lock (Bits 3-11) */
- extru_safe %r26, 28, 8, %r20
+ /* Calculate 8-bit hash index from virtual address */
+ extru_safe %r26, 27, 8, %r20
- /* Find lock to use, the hash is either one of 0 to
- 15, multiplied by 16 (keep it 16-byte aligned)
+ /* Load start of lock table */
+ ldil L%lws_lock_start, %r28
+ ldo R%lws_lock_start(%r28), %r28
+
+ /* Find lock to use, the hash index is one of 0 to
+ 255, multiplied by 16 (keep it 16-byte aligned)
and add to the lock table offset. */
shlw %r20, 4, %r20
add %r20, %r28, %r20
- /* COW breaks can cause contention on UP systems */
- LDCW 0(%sr2,%r20), %r28 /* Try to acquire the lock */
- cmpb,<>,n %r0, %r28, cas2_action /* Did we get it? */
-cas2_wouldblock:
- ldo 2(%r0), %r28 /* 2nd case */
- b lws_exit /* Contended... */
- ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
+ rsm PSW_SM_I, %r0 /* Disable interrupts */
+
+ /* Try to acquire the lock */
+ LDCW 0(%sr2,%r20), %r28
+ comclr,<> %r0, %r28, %r0
+ b,n lws_wouldblock
+
+ /* Disable page faults to prevent sleeping in critical region */
+ lws_pagefault_disable %r21,%r28
/*
prev = *addr;
@@ -775,110 +786,102 @@ cas2_wouldblock:
*/
/* NOTES:
- This all works becuse intr_do_signal
+ This all works because intr_do_signal
and schedule both check the return iasq
and see that we are on the kernel page
so this process is never scheduled off
or is ever sent any signal of any sort,
- thus it is wholly atomic from usrspaces
+ thus it is wholly atomic from usrspace's
perspective
*/
-cas2_action:
+
/* Jump to the correct function */
blr %r29, %r0
/* Set %r28 as non-zero for now */
ldo 1(%r0),%r28
- /* 8bit CAS */
-13: ldb 0(%r26), %r29
+ /* 8-bit CAS */
+12: ldb 0(%r26), %r29
sub,= %r29, %r25, %r0
- b,n cas2_end
-14: stb %r24, 0(%r26)
- b cas2_end
+ b,n lws_exit_noerror
+13: stb %r24, 0(%r26)
+ b lws_exit_noerror
copy %r0, %r28
nop
nop
- /* 16bit CAS */
-15: ldh 0(%r26), %r29
+ /* 16-bit CAS */
+14: ldh 0(%r26), %r29
sub,= %r29, %r25, %r0
- b,n cas2_end
-16: sth %r24, 0(%r26)
- b cas2_end
+ b,n lws_exit_noerror
+15: sth %r24, 0(%r26)
+ b lws_exit_noerror
copy %r0, %r28
nop
nop
- /* 32bit CAS */
-17: ldw 0(%r26), %r29
+ /* 32-bit CAS */
+16: ldw 0(%r26), %r29
sub,= %r29, %r25, %r0
- b,n cas2_end
-18: stw %r24, 0(%r26)
- b cas2_end
+ b,n lws_exit_noerror
+17: stw %r24, 0(%r26)
+ b lws_exit_noerror
copy %r0, %r28
nop
nop
- /* 64bit CAS */
+ /* 64-bit CAS */
#ifdef CONFIG_64BIT
-19: ldd 0(%r26), %r29
+18: ldd 0(%r26), %r29
sub,*= %r29, %r25, %r0
- b,n cas2_end
-20: std %r24, 0(%r26)
+ b,n lws_exit_noerror
+19: std %r24, 0(%r26)
copy %r0, %r28
#else
/* Compare first word */
-19: ldw 0(%r26), %r29
+18: ldw 0(%r26), %r29
sub,= %r29, %r22, %r0
- b,n cas2_end
+ b,n lws_exit_noerror
/* Compare second word */
-20: ldw 4(%r26), %r29
+19: ldw 4(%r26), %r29
sub,= %r29, %r23, %r0
- b,n cas2_end
+ b,n lws_exit_noerror
/* Perform the store */
-21: fstdx %fr4, 0(%r26)
+20: fstdx %fr4, 0(%r26)
copy %r0, %r28
#endif
+ b lws_exit_noerror
+ copy %r0, %r28
-cas2_end:
- /* Free lock */
- stw,ma %r20, 0(%sr2,%r20)
- /* Return to userspace, set no error */
- b lws_exit
- copy %r0, %r21
-
-22:
- /* Error occurred on load or store */
- /* Free lock */
- stw,ma %r20, 0(%sr2,%r20)
- ldo 1(%r0),%r28
- b lws_exit
- ldo -EFAULT(%r0),%r21 /* set errno */
- nop
- nop
- nop
+ /* A fault occurred on load or stbys,e store */
+30: b,n lws_fault
+ ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 30b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 30b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(3b-linux_gateway_page, 30b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 30b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(5b-linux_gateway_page, 30b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(6b-linux_gateway_page, 30b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(7b-linux_gateway_page, 30b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(8b-linux_gateway_page, 30b-linux_gateway_page)
+#ifndef CONFIG_64BIT
+ ASM_EXCEPTIONTABLE_ENTRY(9b-linux_gateway_page, 30b-linux_gateway_page)
+#endif
- /* Exception table entries, for the load and store, return EFAULT.
- Each of the entries must be relocated. */
- ASM_EXCEPTIONTABLE_ENTRY(4b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(5b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(6b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(7b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(8b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(9b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(10b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(11b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(13b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(14b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(15b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(16b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(17b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(18b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(19b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(20b-linux_gateway_page, 22b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(10b-linux_gateway_page, 30b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(11b-linux_gateway_page, 30b-linux_gateway_page)
+
+ /* A page fault occurred in critical region */
+31: b,n lws_pagefault
+ ASM_EXCEPTIONTABLE_ENTRY(12b-linux_gateway_page, 31b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(13b-linux_gateway_page, 31b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(14b-linux_gateway_page, 31b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(15b-linux_gateway_page, 31b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(16b-linux_gateway_page, 31b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(17b-linux_gateway_page, 31b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(18b-linux_gateway_page, 31b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(19b-linux_gateway_page, 31b-linux_gateway_page)
#ifndef CONFIG_64BIT
- ASM_EXCEPTIONTABLE_ENTRY(12b-linux_gateway_page, 22b-linux_gateway_page)
- ASM_EXCEPTIONTABLE_ENTRY(21b-linux_gateway_page, 22b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(20b-linux_gateway_page, 31b-linux_gateway_page)
#endif
/* Make sure nothing else is placed on this page */
@@ -899,7 +902,7 @@ ENTRY(end_linux_gateway_page)
ENTRY(lws_table)
LWS_ENTRY(compare_and_swap32) /* 0 - ELF32 Atomic 32bit CAS */
LWS_ENTRY(compare_and_swap64) /* 1 - ELF64 Atomic 32bit CAS */
- LWS_ENTRY(compare_and_swap_2) /* 2 - ELF32 Atomic 64bit CAS */
+ LWS_ENTRY(compare_and_swap_2) /* 2 - Atomic 64bit CAS */
END(lws_table)
/* End of lws table */
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-12 21:00:09 +0300