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sh: Fix syscall tracing ordering. 

The implementation of system call tracing in the kernel has a
couple of ordering problems:

 - the validity of the system call number is checked before
   calling out to system call tracing code, and should be
   done after

 - the system call number used when tracing is the one the
   system call was invoked with, while the system call tracing
   code can legitimatly change the call number (for example
   strace permutes fork into clone)

This patch fixes both of these problems, and also reoders the
code slightly to make the direct path through the code the
common case.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Stuart Menefy 2006-11-24 13:01:36 +09:00 committed by Paul Mundt
parent c9f0b1c141
commit e0969e0c9b
1 changed files with 22 additions and 23 deletions
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45
arch/sh/kernel/entry-common.S
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@ -256,8 +256,7 @@ syscall_trace_entry:
mov.l @(OFF_R6,r15), r6
mov.l @(OFF_R7,r15), r7 ! arg3
mov.l @(OFF_R3,r15), r3 ! syscall_nr
! Arrange for do_syscall_trace to be called
! again as the system call returns.
!
mov.l 2f, r10 ! Number of syscalls
cmp/hs r10, r3
bf syscall_call
@ -273,6 +272,18 @@ __restore_all:
.align 2
1: .long restore_all
.align 2
not_syscall_tra:
bra debug_trap
nop
.align 2
syscall_badsys: ! Bad syscall number
mov #-ENOSYS, r0
bra resume_userspace
mov.l r0, @(OFF_R0,r15) ! Return value
/*
* Syscall interface:
*
@ -316,39 +327,27 @@ ENTRY(system_call)
! Is the trap argument >= 0x20? (TRA will be >= 0x80)
mov #0x7f, r9
cmp/hi r9, r8
bt/s 0f
bt/s not_syscall_tra
mov #OFF_TRA, r9
add r15, r9
!
mov.l r8, @r9 ! set TRA value to tra
sti
! Call the system call handler through the table.
! First check for bad syscall number
mov r3, r9
mov.l 2f, r8 ! Number of syscalls
cmp/hs r8, r9
!
get_current_thread_info r8, r10
bf good_system_call
syscall_badsys: ! Bad syscall number
mov #-ENOSYS, r0
bra resume_userspace
mov.l r0, @(OFF_R0,r15) ! Return value
!
0:
bra debug_trap
nop
!
good_system_call: ! Good syscall number
mov.l @(TI_FLAGS,r8), r8
mov #_TIF_SYSCALL_TRACE, r10
tst r10, r8
bf syscall_trace_entry
!
mov.l 2f, r8 ! Number of syscalls
cmp/hs r8, r3
bt syscall_badsys
!
syscall_call:
shll2 r9 ! x4
shll2 r3 ! x4
mov.l 3f, r8 ! Load the address of sys_call_table
add r8, r9
mov.l @r9, r8
add r8, r3
mov.l @r3, r8
jsr @r8 ! jump to specific syscall handler
nop
mov.l @(OFF_R0,r15), r12 ! save r0