From: Al Viro <viro@ZenIV.linux.org.uk>
To: sparclinux@vger.kernel.org
Subject: Re: [RESEND PATCH 1/2] sparc64: Rearrange thread info to cheaply clear syscall noerror state.
Date: Sat, 06 Oct 2012 06:06:09 +0000 [thread overview]
Message-ID: <20121006060608.GF2616@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20121004.174812.706050126936137696.davem@davemloft.net>
On Fri, Oct 05, 2012 at 10:43:43PM -0400, David Miller wrote:
> From: Al Viro <viro@ZenIV.linux.org.uk>
> Date: Sat, 6 Oct 2012 00:26:51 +0100
>
> > On Fri, Oct 05, 2012 at 05:48:42PM -0400, David Miller wrote:
> >>
> >> Al, this change turns out to be broken.
> >>
> >> If you move the WSAVED byte down past bit 16, it runs into the bit
> >> mask we for the _TI_* flag bits down lower in the file.
> >
> > Umm... Right you are. I wonder why I hadn't stepped into that while
> > testing that sucker...
>
> I tested it for 20 hours and didn't hit any problems, so don't feel
> bad. :-)
OK, that seems to work; wsaved left where it was. One potential side
benefit is in switch_to(), but I hadn't tried to exploit it; the thing
is, thread_info->cpu and thread_info->current_ds are next to each other,
so we could, in principle, try to exploit that. It doesn't help with
dcache footprint (we need cwp and ->task, so the context switch still
hits both thread_info..thread_info+31 and thread_info+32..thread_info+63
anyway), but it looks like it could be made slightly shorter. Hell
knows; we have lduh and ldub from addresses next to each other (62 and 61
from the current_thread_info(), resp.), so the first one will preload
dcache from the second...
commit 7f41e733823032a8425477cd38c8718fd81a7c00
Author: Al Viro <viro@zeniv.linux.org.uk>
Date: Wed Sep 26 01:21:14 2012 -0400
sparc64: clear syscall_noerror on the entry to syscall, not on the exit
Move that sucker to just before TI_FPDEPTH and replace stb with sth in
etrap_save(). Take current_ds to its old place, so that we don't push
wsaved into TI_... flags. That allows to lose clearing syscall_noerror
on return from syscall.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/sparc/include/asm/ptrace.h b/arch/sparc/include/asm/ptrace.h
index fd9c3f2..eeed804 100644
--- a/arch/sparc/include/asm/ptrace.h
+++ b/arch/sparc/include/asm/ptrace.h
@@ -202,9 +202,7 @@ struct global_reg_snapshot {
};
extern struct global_reg_snapshot global_reg_snapshot[NR_CPUS];
-#define force_successful_syscall_return() \
-do { current_thread_info()->syscall_noerror = 1; \
-} while (0)
+#define force_successful_syscall_return() set_thread_noerror(1)
#define user_mode(regs) (!((regs)->tstate & TSTATE_PRIV))
#define instruction_pointer(regs) ((regs)->tpc)
#define instruction_pointer_set(regs, val) ((regs)->tpc = (val))
diff --git a/arch/sparc/include/asm/switch_to_64.h b/arch/sparc/include/asm/switch_to_64.h
index 7923c4a..cad36f5 100644
--- a/arch/sparc/include/asm/switch_to_64.h
+++ b/arch/sparc/include/asm/switch_to_64.h
@@ -23,7 +23,7 @@ do { flush_tlb_pending(); \
/* If you are tempted to conditionalize the following */ \
/* so that ASI is only written if it changes, think again. */ \
__asm__ __volatile__("wr %%g0, %0, %%asi" \
- : : "r" (__thread_flag_byte_ptr(task_thread_info(next))[TI_FLAG_BYTE_CURRENT_DS]));\
+ : : "r" (task_thread_info(next)->current_ds));\
trap_block[current_thread_info()->cpu].thread = \
task_thread_info(next); \
__asm__ __volatile__( \
diff --git a/arch/sparc/include/asm/thread_info_64.h b/arch/sparc/include/asm/thread_info_64.h
index cfa8c38..389c1e7 100644
--- a/arch/sparc/include/asm/thread_info_64.h
+++ b/arch/sparc/include/asm/thread_info_64.h
@@ -14,12 +14,12 @@
#define TI_FLAG_FAULT_CODE_SHIFT 56
#define TI_FLAG_BYTE_WSTATE 1
#define TI_FLAG_WSTATE_SHIFT 48
-#define TI_FLAG_BYTE_CWP 2
-#define TI_FLAG_CWP_SHIFT 40
-#define TI_FLAG_BYTE_CURRENT_DS 3
-#define TI_FLAG_CURRENT_DS_SHIFT 32
-#define TI_FLAG_BYTE_FPDEPTH 4
-#define TI_FLAG_FPDEPTH_SHIFT 24
+#define TI_FLAG_BYTE_NOERROR 2
+#define TI_FLAG_BYTE_NOERROR_SHIFT 40
+#define TI_FLAG_BYTE_FPDEPTH 3
+#define TI_FLAG_FPDEPTH_SHIFT 32
+#define TI_FLAG_BYTE_CWP 4
+#define TI_FLAG_CWP_SHIFT 24
#define TI_FLAG_BYTE_WSAVED 5
#define TI_FLAG_WSAVED_SHIFT 16
@@ -47,7 +47,7 @@ struct thread_info {
struct exec_domain *exec_domain;
int preempt_count; /* 0 => preemptable, <0 => BUG */
__u8 new_child;
- __u8 syscall_noerror;
+ __u8 current_ds;
__u16 cpu;
unsigned long *utraps;
@@ -74,9 +74,9 @@ struct thread_info {
#define TI_FAULT_CODE (TI_FLAGS + TI_FLAG_BYTE_FAULT_CODE)
#define TI_WSTATE (TI_FLAGS + TI_FLAG_BYTE_WSTATE)
#define TI_CWP (TI_FLAGS + TI_FLAG_BYTE_CWP)
-#define TI_CURRENT_DS (TI_FLAGS + TI_FLAG_BYTE_CURRENT_DS)
#define TI_FPDEPTH (TI_FLAGS + TI_FLAG_BYTE_FPDEPTH)
#define TI_WSAVED (TI_FLAGS + TI_FLAG_BYTE_WSAVED)
+#define TI_SYS_NOERROR (TI_FLAGS + TI_FLAG_BYTE_NOERROR)
#define TI_FPSAVED 0x00000010
#define TI_KSP 0x00000018
#define TI_FAULT_ADDR 0x00000020
@@ -84,7 +84,7 @@ struct thread_info {
#define TI_EXEC_DOMAIN 0x00000030
#define TI_PRE_COUNT 0x00000038
#define TI_NEW_CHILD 0x0000003c
-#define TI_SYS_NOERROR 0x0000003d
+#define TI_CURRENT_DS 0x0000003d
#define TI_CPU 0x0000003e
#define TI_UTRAPS 0x00000040
#define TI_REG_WINDOW 0x00000048
@@ -121,7 +121,7 @@ struct thread_info {
#define INIT_THREAD_INFO(tsk) \
{ \
.task = &tsk, \
- .flags = ((unsigned long)ASI_P) << TI_FLAG_CURRENT_DS_SHIFT, \
+ .current_ds = ASI_P, \
.exec_domain = &default_exec_domain, \
.preempt_count = INIT_PREEMPT_COUNT, \
.restart_block = { \
@@ -153,13 +153,12 @@ register struct thread_info *current_thread_info_reg asm("g6");
#define set_thread_wstate(val) (__cur_thread_flag_byte_ptr[TI_FLAG_BYTE_WSTATE] = (val))
#define get_thread_cwp() (__cur_thread_flag_byte_ptr[TI_FLAG_BYTE_CWP])
#define set_thread_cwp(val) (__cur_thread_flag_byte_ptr[TI_FLAG_BYTE_CWP] = (val))
-#define get_thread_current_ds() (__cur_thread_flag_byte_ptr[TI_FLAG_BYTE_CURRENT_DS])
-#define set_thread_current_ds(val) (__cur_thread_flag_byte_ptr[TI_FLAG_BYTE_CURRENT_DS] = (val))
+#define get_thread_noerror() (__cur_thread_flag_byte_ptr[TI_FLAG_BYTE_NOERROR])
+#define set_thread_noerror(val) (__cur_thread_flag_byte_ptr[TI_FLAG_BYTE_NOERROR] = (val))
#define get_thread_fpdepth() (__cur_thread_flag_byte_ptr[TI_FLAG_BYTE_FPDEPTH])
#define set_thread_fpdepth(val) (__cur_thread_flag_byte_ptr[TI_FLAG_BYTE_FPDEPTH] = (val))
#define get_thread_wsaved() (__cur_thread_flag_byte_ptr[TI_FLAG_BYTE_WSAVED])
#define set_thread_wsaved(val) (__cur_thread_flag_byte_ptr[TI_FLAG_BYTE_WSAVED] = (val))
-
#endif /* !(__ASSEMBLY__) */
/*
diff --git a/arch/sparc/include/asm/uaccess_64.h b/arch/sparc/include/asm/uaccess_64.h
index 7c831d8..3eef541 100644
--- a/arch/sparc/include/asm/uaccess_64.h
+++ b/arch/sparc/include/asm/uaccess_64.h
@@ -38,14 +38,14 @@
#define VERIFY_READ 0
#define VERIFY_WRITE 1
-#define get_fs() ((mm_segment_t) { get_thread_current_ds() })
+#define get_fs() ((mm_segment_t){(current_thread_info()->current_ds)})
#define get_ds() (KERNEL_DS)
#define segment_eq(a,b) ((a).seg = (b).seg)
#define set_fs(val) \
do { \
- set_thread_current_ds((val).seg); \
+ current_thread_info()->current_ds =(val).seg; \
__asm__ __volatile__ ("wr %%g0, %0, %%asi" : : "r" ((val).seg)); \
} while(0)
diff --git a/arch/sparc/kernel/etrap_64.S b/arch/sparc/kernel/etrap_64.S
index 786b185..1276ca2 100644
--- a/arch/sparc/kernel/etrap_64.S
+++ b/arch/sparc/kernel/etrap_64.S
@@ -92,8 +92,10 @@ etrap_save: save %g2, -STACK_BIAS, %sp
rdpr %wstate, %g2
wrpr %g0, 0, %canrestore
sll %g2, 3, %g2
+
+ /* Set TI_SYS_FPDEPTH to 1 and clear TI_SYS_NOERROR. */
mov 1, %l5
- stb %l5, [%l6 + TI_FPDEPTH]
+ sth %l5, [%l6 + TI_SYS_NOERROR]
wrpr %g3, 0, %otherwin
wrpr %g2, 0, %wstate
@@ -152,7 +154,9 @@ etrap_save: save %g2, -STACK_BIAS, %sp
add %l6, TI_FPSAVED + 1, %l4
srl %l5, 1, %l3
add %l5, 2, %l5
- stb %l5, [%l6 + TI_FPDEPTH]
+
+ /* Set TI_SYS_FPDEPTH to %l5 and clear TI_SYS_NOERROR. */
+ sth %l5, [%l6 + TI_SYS_NOERROR]
ba,pt %xcc, 2b
stb %g0, [%l4 + %l3]
nop
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index aff0c72..aa6d72c 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -557,9 +557,8 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
(THREAD_SIZE - child_stack_sz));
memcpy(child_trap_frame, parent_sf, child_stack_sz);
- t->flags = (t->flags & ~((0xffUL << TI_FLAG_CWP_SHIFT) |
- (0xffUL << TI_FLAG_CURRENT_DS_SHIFT))) |
- (((regs->tstate + 1) & TSTATE_CWP) << TI_FLAG_CWP_SHIFT);
+ __thread_flag_byte_ptr(t)[TI_FLAG_BYTE_CWP] =
+ (regs->tstate + 1) & TSTATE_CWP;
t->new_child = 1;
t->ksp = ((unsigned long) child_trap_frame) - STACK_BIAS;
t->kregs = (struct pt_regs *) (child_trap_frame +
@@ -575,7 +574,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
t->kregs->u_regs[UREG_FP] ((unsigned long) child_sf) - STACK_BIAS;
- t->flags |= ((long)ASI_P << TI_FLAG_CURRENT_DS_SHIFT);
+ t->current_ds = ASI_P;
t->kregs->u_regs[UREG_G6] = (unsigned long) t;
t->kregs->u_regs[UREG_G4] = (unsigned long) t->task;
} else {
@@ -584,7 +583,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
regs->u_regs[UREG_FP] &= 0x00000000ffffffffUL;
}
t->kregs->u_regs[UREG_FP] = sp;
- t->flags |= ((long)ASI_AIUS << TI_FLAG_CURRENT_DS_SHIFT);
+ t->current_ds = ASI_AIUS;
if (sp != regs->u_regs[UREG_FP]) {
unsigned long csp;
diff --git a/arch/sparc/kernel/syscalls.S b/arch/sparc/kernel/syscalls.S
index 1d7e274..ed277e2 100644
--- a/arch/sparc/kernel/syscalls.S
+++ b/arch/sparc/kernel/syscalls.S
@@ -221,8 +221,8 @@ ret_sys_call:
* was invoked.
*/
ldub [%g6 + TI_SYS_NOERROR], %l2
- brnz,a,pn %l2, 80f
- stb %g0, [%g6 + TI_SYS_NOERROR]
+ brnz,pn %l2, 80f
+ nop
cmp %o0, -ERESTART_RESTARTBLOCK
bgeu,pn %xcc, 1f
diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c
index 3b05e66..b3c337c 100644
--- a/arch/sparc/kernel/traps_64.c
+++ b/arch/sparc/kernel/traps_64.c
@@ -2547,8 +2547,8 @@ void __init trap_init(void)
TI_PRE_COUNT != offsetof(struct thread_info,
preempt_count) ||
TI_NEW_CHILD != offsetof(struct thread_info, new_child) ||
- TI_SYS_NOERROR != offsetof(struct thread_info,
- syscall_noerror) ||
+ TI_CURRENT_DS != offsetof(struct thread_info,
+ current_ds) ||
TI_RESTART_BLOCK != offsetof(struct thread_info,
restart_block) ||
TI_KUNA_REGS != offsetof(struct thread_info,
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index 696bb09..ce32e9f 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -615,7 +615,8 @@ static void __init inherit_prom_mappings(void)
void prom_world(int enter)
{
if (!enter)
- set_fs((mm_segment_t) { get_thread_current_ds() });
+ __asm__ __volatile__ ("wr %%g0, %0, %%asi" : :
+ "r" (current_thread_info()->current_ds ));
__asm__ __volatile__("flushw");
}
next prev parent reply other threads:[~2012-10-06 6:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-04 21:48 [RESEND PATCH 1/2] sparc64: Rearrange thread info to cheaply clear syscall noerror state David Miller
2012-10-05 21:48 ` David Miller
2012-10-05 23:26 ` Al Viro
2012-10-06 2:43 ` David Miller
2012-10-06 2:50 ` Al Viro
2012-10-06 3:49 ` David Miller
2012-10-06 6:06 ` Al Viro [this message]
2012-10-08 19:29 ` David Miller
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