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.
