Masami Hiramatsu wrote on Thursday, June 15, 2006 6:27 AM
> I found a suspicious buggy code in the linux kernel on IA64 arch.
> As far as I can see, search_extable() doesn't work correctly, because
> the lookup routine expects that the address format of the
> exception_table_entry is "IP + slot", but the compiler (gcc-3.4.5)
> generates it as "IP + (slot << 2)". Thus the lookup routine always
> fails to find the corresponding entry.
> You can check it by dumping __ex_table section of vmlinux.
Chen, Kenneth W wrote on Thursday, June 15, 2006 2:22 PM
> But the tag address in the table is also bundle aligned, which I will
> look a bit more.
I've double checked (triple checked with sample test code below). It's a
false alarm. Everyone should rest assure that exception table and compiler
do match and generates correct code. There is no bug AFAICT.
Test code:
#include <linux/config.h>
#include <asm/asmmacro.h>
GLOBAL_ENTRY(ken)
EX(eh0, ld1 r32 = [r0])
EX(eh1, ld1 r33 = [r0])
nop 0
;;
[eh0:] br.ret.sptk b0
[eh1:] br.ret.sptk b0
END(ken)
Exception table entry for eh0 and eh1:
0xa0000001004bc828 ffff7518 ffff7524 ffff7511 ffff751d
objdump of test code:
a0000001004b3d40: ld1 r32=[r0]
a0000001004b3d46: ld1 r33=[r0]
a0000001004b3d4c: nop.i 0x0;;
a0000001004b3d50: br.ret.sptk.few b0
a0000001004b3d56: br.ret.sptk.few b0
a0000001004b3d5c: nop.b 0x0;;
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