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>
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@ -256,8 +256,7 @@ syscall_trace_entry:
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mov.l @(OFF_R6,r15), r6
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mov.l @(OFF_R7,r15), r7 ! arg3
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mov.l @(OFF_R3,r15), r3 ! syscall_nr
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! Arrange for do_syscall_trace to be called
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! again as the system call returns.
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!
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mov.l 2f, r10 ! Number of syscalls
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cmp/hs r10, r3
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bf syscall_call
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@ -273,6 +272,18 @@ __restore_all:
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.align 2
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1: .long restore_all
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.align 2
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not_syscall_tra:
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bra debug_trap
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nop
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.align 2
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syscall_badsys: ! Bad syscall number
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mov #-ENOSYS, r0
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bra resume_userspace
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mov.l r0, @(OFF_R0,r15) ! Return value
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/*
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* Syscall interface:
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*
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@ -316,39 +327,27 @@ ENTRY(system_call)
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! Is the trap argument >= 0x20? (TRA will be >= 0x80)
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mov #0x7f, r9
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cmp/hi r9, r8
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bt/s 0f
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bt/s not_syscall_tra
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mov #OFF_TRA, r9
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add r15, r9
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!
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mov.l r8, @r9 ! set TRA value to tra
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sti
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! Call the system call handler through the table.
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! First check for bad syscall number
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mov r3, r9
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mov.l 2f, r8 ! Number of syscalls
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cmp/hs r8, r9
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!
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get_current_thread_info r8, r10
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bf good_system_call
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syscall_badsys: ! Bad syscall number
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mov #-ENOSYS, r0
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bra resume_userspace
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mov.l r0, @(OFF_R0,r15) ! Return value
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!
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0:
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bra debug_trap
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nop
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!
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good_system_call: ! Good syscall number
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mov.l @(TI_FLAGS,r8), r8
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mov #_TIF_SYSCALL_TRACE, r10
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tst r10, r8
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bf syscall_trace_entry
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!
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mov.l 2f, r8 ! Number of syscalls
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cmp/hs r8, r3
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bt syscall_badsys
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!
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syscall_call:
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shll2 r9 ! x4
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shll2 r3 ! x4
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mov.l 3f, r8 ! Load the address of sys_call_table
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add r8, r9
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mov.l @r9, r8
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add r8, r3
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mov.l @r3, r8
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jsr @r8 ! jump to specific syscall handler
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nop
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mov.l @(OFF_R0,r15), r12 ! save r0
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