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-rw-r--r--arch/parisc/kernel/syscall.S122
1 files changed, 73 insertions, 49 deletions
diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index 59fc1a43ec3..83878601103 100644
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -1,12 +1,35 @@
/*
* Linux/PA-RISC Project (http://www.parisc-linux.org/)
*
- * System call entry code Copyright (c) Matthew Wilcox 1999 <willy@bofh.ai>
+ * System call entry code / Linux gateway page
+ * Copyright (c) Matthew Wilcox 1999 <willy@bofh.ai>
* Licensed under the GNU GPL.
* thanks to Philipp Rumpf, Mike Shaver and various others
* sorry about the wall, puffin..
*/
+/*
+How does the Linux gateway page on PA-RISC work?
+------------------------------------------------
+The Linux gateway page on PA-RISC is "special".
+It actually has PAGE_GATEWAY bits set (this is linux terminology; in parisc
+terminology it's Execute, promote to PL0) in the page map. So anything
+executing on this page executes with kernel level privilege (there's more to it
+than that: to have this happen, you also have to use a branch with a ,gate
+completer to activate the privilege promotion). The upshot is that everything
+that runs on the gateway page runs at kernel privilege but with the current
+user process address space (although you have access to kernel space via %sr2).
+For the 0x100 syscall entry, we redo the space registers to point to the kernel
+address space (preserving the user address space in %sr3), move to wide mode if
+required, save the user registers and branch into the kernel syscall entry
+point. For all the other functions, we execute at kernel privilege but don't
+flip address spaces. The basic upshot of this is that these code snippets are
+executed atomically (because the kernel can't be pre-empted) and they may
+perform architecturally forbidden (to PL3) operations (like setting control
+registers).
+*/
+
+
#include <asm/asm-offsets.h>
#include <asm/unistd.h>
#include <asm/errno.h>
@@ -15,6 +38,7 @@
#include <asm/thread_info.h>
#include <asm/assembly.h>
#include <asm/processor.h>
+#include <asm/cache.h>
#include <linux/linkage.h>
@@ -47,18 +71,17 @@ ENTRY(linux_gateway_page)
KILL_INSN
.endr
- /* ADDRESS 0xb0 to 0xb4, lws uses 1 insns for entry */
+ /* ADDRESS 0xb0 to 0xb8, lws uses two insns for entry */
/* Light-weight-syscall entry must always be located at 0xb0 */
/* WARNING: Keep this number updated with table size changes */
#define __NR_lws_entries (2)
lws_entry:
- /* Unconditional branch to lws_start, located on the
- same gateway page */
- b,n lws_start
+ gate lws_start, %r0 /* increase privilege */
+ depi 3, 31, 2, %r31 /* Ensure we return into user mode. */
- /* Fill from 0xb4 to 0xe0 */
- .rept 11
+ /* Fill from 0xb8 to 0xe0 */
+ .rept 10
KILL_INSN
.endr
@@ -157,7 +180,7 @@ linux_gateway_entry:
STREG %r26, TASK_PT_GR26(%r1) /* 1st argument */
STREG %r27, TASK_PT_GR27(%r1) /* user dp */
STREG %r28, TASK_PT_GR28(%r1) /* return value 0 */
- STREG %r28, TASK_PT_ORIG_R28(%r1) /* return value 0 (saved for signals) */
+ STREG %r0, TASK_PT_ORIG_R28(%r1) /* don't prohibit restarts */
STREG %r29, TASK_PT_GR29(%r1) /* return value 1 */
STREG %r31, TASK_PT_GR31(%r1) /* preserve syscall return ptr */
@@ -181,9 +204,10 @@ linux_gateway_entry:
/* Are we being ptraced? */
mfctl %cr30, %r1
- LDREG TI_TASK(%r1),%r1
- ldw TASK_PTRACE(%r1), %r1
- bb,<,n %r1,31,.Ltracesys
+ LDREG TI_FLAGS(%r1),%r1
+ ldi _TIF_SYSCALL_TRACE_MASK, %r19
+ and,COND(=) %r1, %r19, %r0
+ b,n .Ltracesys
/* Note! We cannot use the syscall table that is mapped
nearby since the gateway page is mapped execute-only. */
@@ -288,26 +312,34 @@ tracesys:
STREG %r18,PT_GR18(%r2)
/* Finished saving things for the debugger */
- ldil L%syscall_trace,%r1
+ copy %r2,%r26
+ ldil L%do_syscall_trace_enter,%r1
ldil L%tracesys_next,%r2
- be R%syscall_trace(%sr7,%r1)
+ be R%do_syscall_trace_enter(%sr7,%r1)
ldo R%tracesys_next(%r2),%r2
-tracesys_next:
+tracesys_next:
+ /* do_syscall_trace_enter either returned the syscallno, or -1L,
+ * so we skip restoring the PT_GR20 below, since we pulled it from
+ * task->thread.regs.gr[20] above.
+ */
+ copy %ret0,%r20
ldil L%sys_call_table,%r1
ldo R%sys_call_table(%r1), %r19
ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
LDREG TI_TASK(%r1), %r1
- LDREG TASK_PT_GR20(%r1), %r20
LDREG TASK_PT_GR26(%r1), %r26 /* Restore the users args */
LDREG TASK_PT_GR25(%r1), %r25
LDREG TASK_PT_GR24(%r1), %r24
LDREG TASK_PT_GR23(%r1), %r23
-#ifdef CONFIG_64BIT
LDREG TASK_PT_GR22(%r1), %r22
LDREG TASK_PT_GR21(%r1), %r21
+#ifdef CONFIG_64BIT
ldo -16(%r30),%r29 /* Reference param save area */
+#else
+ stw %r22, -52(%r30) /* 5th argument */
+ stw %r21, -56(%r30) /* 6th argument */
#endif
comiclr,>>= __NR_Linux_syscalls, %r20, %r0
@@ -336,7 +368,8 @@ tracesys_exit:
#ifdef CONFIG_64BIT
ldo -16(%r30),%r29 /* Reference param save area */
#endif
- bl syscall_trace, %r2
+ ldo TASK_REGS(%r1),%r26
+ bl do_syscall_trace_exit,%r2
STREG %r28,TASK_PT_GR28(%r1) /* save return value now */
ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
LDREG TI_TASK(%r1), %r1
@@ -353,12 +386,12 @@ tracesys_exit:
tracesys_sigexit:
ldo -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1 /* get task ptr */
- LDREG 0(%r1), %r1
+ LDREG TI_TASK(%r1), %r1
#ifdef CONFIG_64BIT
ldo -16(%r30),%r29 /* Reference param save area */
#endif
- bl syscall_trace, %r2
- nop
+ bl do_syscall_trace_exit,%r2
+ ldo TASK_REGS(%r1),%r26
ldil L%syscall_exit_rfi,%r1
be,n R%syscall_exit_rfi(%sr7,%r1)
@@ -417,9 +450,6 @@ tracesys_sigexit:
*********************************************************/
lws_start:
- /* Gate and ensure we return to userspace */
- gate .+8, %r0
- depi 3, 31, 2, %r31 /* Ensure we return to userspace */
#ifdef CONFIG_64BIT
/* FIXME: If we are a 64-bit kernel just
@@ -436,7 +466,7 @@ lws_start:
#endif
/* Is the lws entry number valid? */
- comiclr,>>= __NR_lws_entries, %r20, %r0
+ comiclr,>> __NR_lws_entries, %r20, %r0
b,n lws_exit_nosys
/* WARNING: Trashing sr2 and sr3 */
@@ -467,7 +497,7 @@ lws_exit:
/* now reset the lowest bit of sp if it was set */
xor %r30,%r1,%r30
#endif
- be,n 0(%sr3, %r31)
+ be,n 0(%sr7, %r31)
@@ -523,7 +553,6 @@ lws_compare_and_swap32:
#endif
lws_compare_and_swap:
-#ifdef CONFIG_SMP
/* Load start of lock table */
ldil L%lws_lock_start, %r20
ldo R%lws_lock_start(%r20), %r28
@@ -560,14 +589,15 @@ cas_nocontend:
# endif
/* ENABLE_LWS_DEBUG */
+ rsm PSW_SM_I, %r0 /* Disable interrupts */
+ /* 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 */
+ ssm PSW_SM_I, %r0
b lws_exit /* Contended... */
ldo -EAGAIN(%r0), %r21 /* Spin in userspace */
-#endif
-/* CONFIG_SMP */
/*
prev = *addr;
@@ -592,30 +622,29 @@ cas_action:
stw %r1, 4(%sr2,%r20)
#endif
/* The load and store could fail */
-1: ldw 0(%sr3,%r26), %r28
+1: ldw,ma 0(%sr3,%r26), %r28
sub,<> %r28, %r25, %r0
-2: stw %r24, 0(%sr3,%r26)
-#ifdef CONFIG_SMP
+2: stw,ma %r24, 0(%sr3,%r26)
/* Free lock */
- stw %r20, 0(%sr2,%r20)
-# if ENABLE_LWS_DEBUG
+ stw,ma %r20, 0(%sr2,%r20)
+#if ENABLE_LWS_DEBUG
/* Clear thread register indicator */
stw %r0, 4(%sr2,%r20)
-# endif
#endif
+ /* Enable interrupts */
+ ssm PSW_SM_I, %r0
/* Return to userspace, set no error */
b lws_exit
copy %r0, %r21
3:
- /* Error occured on load or store */
-#ifdef CONFIG_SMP
+ /* Error occurred on load or store */
/* Free lock */
stw %r20, 0(%sr2,%r20)
-# if ENABLE_LWS_DEBUG
+#if ENABLE_LWS_DEBUG
stw %r0, 4(%sr2,%r20)
-# endif
#endif
+ ssm PSW_SM_I, %r0
b lws_exit
ldo -EFAULT(%r0),%r21 /* set errno */
nop
@@ -626,10 +655,8 @@ cas_action:
/* Two exception table entries, one for the load,
the other for the store. Either return -EFAULT.
Each of the entries must be relocated. */
- .section __ex_table,"aw"
- ASM_ULONG_INSN (1b - linux_gateway_page), (3b - linux_gateway_page)
- ASM_ULONG_INSN (2b - linux_gateway_page), (3b - linux_gateway_page)
- .previous
+ ASM_EXCEPTIONTABLE_ENTRY(1b-linux_gateway_page, 3b-linux_gateway_page)
+ ASM_EXCEPTIONTABLE_ENTRY(2b-linux_gateway_page, 3b-linux_gateway_page)
/* Make sure nothing else is placed on this page */
@@ -644,7 +671,7 @@ ENTRY(end_linux_gateway_page)
.section .rodata,"a"
- .align PAGE_SIZE
+ .align 8
/* Light-weight-syscall table */
/* Start of lws table. */
ENTRY(lws_table)
@@ -653,20 +680,19 @@ ENTRY(lws_table)
END(lws_table)
/* End of lws table */
- .align PAGE_SIZE
+ .align 8
ENTRY(sys_call_table)
#include "syscall_table.S"
END(sys_call_table)
#ifdef CONFIG_64BIT
- .align PAGE_SIZE
+ .align 8
ENTRY(sys_call_table64)
#define SYSCALL_TABLE_64BIT
#include "syscall_table.S"
END(sys_call_table64)
#endif
-#ifdef CONFIG_SMP
/*
All light-weight-syscall atomic operations
will use this set of locks
@@ -676,7 +702,7 @@ END(sys_call_table64)
with ldcw.
*/
.section .data
- .align PAGE_SIZE
+ .align L1_CACHE_BYTES
ENTRY(lws_lock_start)
/* lws locks */
.rept 16
@@ -688,8 +714,6 @@ ENTRY(lws_lock_start)
.endr
END(lws_lock_start)
.previous
-#endif
-/* CONFIG_SMP for lws_lock_start */
.end
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-12-05 20:40:39 +0000