* bug in handle_sys?
@ 2004-03-29 4:27 Fuxin Zhang
2004-03-30 2:21 ` Fuxin Zhang
0 siblings, 1 reply; 3+ messages in thread
From: Fuxin Zhang @ 2004-03-29 4:27 UTC (permalink / raw)
To: linux-mips
Hi,
My colleague finds that there is probably a bug in handle_sys:
.align 5
NESTED(handle_sys, PT_SIZE, sp)
.set noat
SAVE_SOME
STI
.set at
lw t1, PT_EPC(sp) # skip syscall on return
sltiu t0, v0, MAX_SYSCALL_NO + 1 # check syscall number
addiu t1, 4 # skip to next instruction
beqz t0, illegal_syscall
sw t1, PT_EPC(sp)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This code is not guarded by .set no reorder,so it won't be the delay slot
instruction,thus illegal_syscall with num > MAX_SYSCALL_NO will return with
EPC unchanged. The reason it works is that the syscall number register
v0 will
be changed to ENOSYS. ENOSYS is fortunately another illegal syscall number
that will take another illegal_syscall return path.
Newer glibc of debian(2.3.2+?) will generate sys_4246,and that lead to real
problem for mips64. Put the line ahead of the beqz solve it.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: bug in handle_sys?
@ 2004-03-30 2:21 ` Fuxin Zhang
0 siblings, 0 replies; 3+ messages in thread
From: Fuxin Zhang @ 2004-03-30 2:21 UTC (permalink / raw)
Cc: linux-mips
Hi,all
It seems the fix is a little more complex than I had thought
because we've to make sure every configuration works,so a patch
is attached below.
And during the reading of related code,we can't find code in mips64
to ensure correct handle of too small a syscall number? For mips we
have reserved space for nr<4000,but now it seems random. Do we need to
fix that too?
===================================================================
RCS file: /home/cvs/linux-godson2/arch/mips64/kernel/scall_o32.S,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -r1.3 -r1.4
--- scall_o32.S 16 Oct 2003 16:18:15 -0000 1.3
+++ scall_o32.S 27 Mar 2004 14:58:11 -0000 1.4
@@ -33,8 +33,8 @@
subu t0, v0, __NR_O32_Linux # check syscall number
sltiu t0, t0, __NR_O32_Linux_syscalls + 1
daddiu t1, 4 # skip to next instruction
- beqz t0, not_o32_scall
sd t1, PT_EPC(sp)
+ beqz t0, not_o32_scall
#if 0
SAVE_ALL
move a1, v0
Index: scall_n32.S
===================================================================
RCS file: /home/cvs/linux-godson2/arch/mips64/kernel/scall_n32.S,v
retrieving revision 1.4
retrieving revision 1.6
diff -u -r1.4 -r1.6
--- scall_n32.S 16 Oct 2003 16:18:15 -0000 1.4
+++ scall_n32.S 29 Mar 2004 13:41:45 -0000 1.6
@@ -35,13 +35,16 @@
STI
.set at
#endif
- ld t1, PT_EPC(sp) # skip syscall on return
subu t0, v0, __NR_N32_Linux # check syscall number
sltiu t0, t0, __NR_N32_Linux_syscalls + 1
+
+#ifndef CONFIG_MIPS32_O32
+ ld t1, PT_EPC(sp) # skip syscall on return
daddiu t1, 4 # skip to next instruction
- beqz t0, not_n32_scall
sd t1, PT_EPC(sp)
+#endif
+ beqz t0, not_n32_scall
dsll t0, v0, 3 # offset into table
ld t2, (sysn32_call_table - (__NR_N32_Linux * 8))(t0)
Index: scall_64.S
===================================================================
RCS file: /home/cvs/linux-godson2/arch/mips64/kernel/scall_64.S,v
retrieving revision 1.2
retrieving revision 1.4
diff -u -r1.2 -r1.4
--- scall_64.S 16 Oct 2003 16:18:15 -0000 1.2
+++ scall_64.S 29 Mar 2004 13:41:44 -0000 1.4
@@ -31,13 +31,15 @@
STI
.set at
#endif
- ld t1, PT_EPC(sp) # skip syscall on return
-
subu t0, v0, __NR_Linux # check syscall number
sltiu t0, t0, __NR_Linux_syscalls + 1
+
+#if !defined(CONFIG_MIPS32_O32) && !defined(CONFIG_MIPS32_N32)
+ ld t1, PT_EPC(sp) # skip syscall on return
daddiu t1, 4 # skip to next instruction
- beqz t0, illegal_syscall
sd t1, PT_EPC(sp)
+#endif
+ beqz t0, illegal_syscall
dsll t0, v0, 3 # offset into table
ld t2, (sys_call_table - (__NR_Linux * 8))(t0) # syscall routine
Fuxin Zhang wrote:
> Hi,
>
> My colleague finds that there is probably a bug in handle_sys:
>
> .align 5
> NESTED(handle_sys, PT_SIZE, sp)
> .set noat
> SAVE_SOME
> STI
> .set at
>
> lw t1, PT_EPC(sp) # skip syscall on return
>
> sltiu t0, v0, MAX_SYSCALL_NO + 1 # check syscall number
> addiu t1, 4 # skip to next instruction
> beqz t0, illegal_syscall
> sw t1, PT_EPC(sp)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> This code is not guarded by .set no reorder,so it won't be the delay slot
> instruction,thus illegal_syscall with num > MAX_SYSCALL_NO will return
> with
> EPC unchanged. The reason it works is that the syscall number register
> v0 will
> be changed to ENOSYS. ENOSYS is fortunately another illegal syscall
> number
> that will take another illegal_syscall return path.
>
> Newer glibc of debian(2.3.2+?) will generate sys_4246,and that lead to
> real
> problem for mips64. Put the line ahead of the beqz solve it.
>
>
>
>
>
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: bug in handle_sys?
@ 2004-03-30 2:21 ` Fuxin Zhang
0 siblings, 0 replies; 3+ messages in thread
From: Fuxin Zhang @ 2004-03-30 2:21 UTC (permalink / raw)
Cc: linux-mips
Hi,all
It seems the fix is a little more complex than I had thought
because we've to make sure every configuration works,so a patch
is attached below.
And during the reading of related code,we can't find code in mips64
to ensure correct handle of too small a syscall number? For mips we
have reserved space for nr<4000,but now it seems random. Do we need to
fix that too?
===================================================================
RCS file: /home/cvs/linux-godson2/arch/mips64/kernel/scall_o32.S,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -r1.3 -r1.4
--- scall_o32.S 16 Oct 2003 16:18:15 -0000 1.3
+++ scall_o32.S 27 Mar 2004 14:58:11 -0000 1.4
@@ -33,8 +33,8 @@
subu t0, v0, __NR_O32_Linux # check syscall number
sltiu t0, t0, __NR_O32_Linux_syscalls + 1
daddiu t1, 4 # skip to next instruction
- beqz t0, not_o32_scall
sd t1, PT_EPC(sp)
+ beqz t0, not_o32_scall
#if 0
SAVE_ALL
move a1, v0
Index: scall_n32.S
===================================================================
RCS file: /home/cvs/linux-godson2/arch/mips64/kernel/scall_n32.S,v
retrieving revision 1.4
retrieving revision 1.6
diff -u -r1.4 -r1.6
--- scall_n32.S 16 Oct 2003 16:18:15 -0000 1.4
+++ scall_n32.S 29 Mar 2004 13:41:45 -0000 1.6
@@ -35,13 +35,16 @@
STI
.set at
#endif
- ld t1, PT_EPC(sp) # skip syscall on return
subu t0, v0, __NR_N32_Linux # check syscall number
sltiu t0, t0, __NR_N32_Linux_syscalls + 1
+
+#ifndef CONFIG_MIPS32_O32
+ ld t1, PT_EPC(sp) # skip syscall on return
daddiu t1, 4 # skip to next instruction
- beqz t0, not_n32_scall
sd t1, PT_EPC(sp)
+#endif
+ beqz t0, not_n32_scall
dsll t0, v0, 3 # offset into table
ld t2, (sysn32_call_table - (__NR_N32_Linux * 8))(t0)
Index: scall_64.S
===================================================================
RCS file: /home/cvs/linux-godson2/arch/mips64/kernel/scall_64.S,v
retrieving revision 1.2
retrieving revision 1.4
diff -u -r1.2 -r1.4
--- scall_64.S 16 Oct 2003 16:18:15 -0000 1.2
+++ scall_64.S 29 Mar 2004 13:41:44 -0000 1.4
@@ -31,13 +31,15 @@
STI
.set at
#endif
- ld t1, PT_EPC(sp) # skip syscall on return
-
subu t0, v0, __NR_Linux # check syscall number
sltiu t0, t0, __NR_Linux_syscalls + 1
+
+#if !defined(CONFIG_MIPS32_O32) && !defined(CONFIG_MIPS32_N32)
+ ld t1, PT_EPC(sp) # skip syscall on return
daddiu t1, 4 # skip to next instruction
- beqz t0, illegal_syscall
sd t1, PT_EPC(sp)
+#endif
+ beqz t0, illegal_syscall
dsll t0, v0, 3 # offset into table
ld t2, (sys_call_table - (__NR_Linux * 8))(t0) # syscall routine
Fuxin Zhang wrote:
> Hi,
>
> My colleague finds that there is probably a bug in handle_sys:
>
> .align 5
> NESTED(handle_sys, PT_SIZE, sp)
> .set noat
> SAVE_SOME
> STI
> .set at
>
> lw t1, PT_EPC(sp) # skip syscall on return
>
> sltiu t0, v0, MAX_SYSCALL_NO + 1 # check syscall number
> addiu t1, 4 # skip to next instruction
> beqz t0, illegal_syscall
> sw t1, PT_EPC(sp)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> This code is not guarded by .set no reorder,so it won't be the delay slot
> instruction,thus illegal_syscall with num > MAX_SYSCALL_NO will return
> with
> EPC unchanged. The reason it works is that the syscall number register
> v0 will
> be changed to ENOSYS. ENOSYS is fortunately another illegal syscall
> number
> that will take another illegal_syscall return path.
>
> Newer glibc of debian(2.3.2+?) will generate sys_4246,and that lead to
> real
> problem for mips64. Put the line ahead of the beqz solve it.
>
>
>
>
>
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2004-03-30 2:21 UTC | newest]
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2004-03-29 4:27 bug in handle_sys? Fuxin Zhang
2004-03-30 2:21 ` Fuxin Zhang
2004-03-30 2:21 ` Fuxin Zhang
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