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Firstly, Loongson-2EF support ll/sc instructions, but
doesn't need fix-loongson3-llsc compile option.
Secondly, fix-loongson3-llsc will cause kernel startup
fail at futex_init, because compiler will add 'sync' before
'll', which will affect __ex_table.
futex_init will pass NULL uaddr parameter to
futex_atomic_cmpxchg_inatomic.
futex_atomic_cmpxchg_inatomic will access uaddr directly,
which will cause page fault exception, the exception should be
handled by __ex_table's nextinsn if the exception insn exsit in
__ex_table. Because __ex_table is affected by compiler,
the exception can not be handled, and
futex_atomic_cmpxchg_inatomic will crash.
Error code as below:
__ex_table.insn = 1b, which is 'sync' compiled with
fix-loongson3-llsc, but the actual exception instrction is ll.
So, do_page_fault will not find the correct inst in __ex_table, and
can not handle this exception.
"1: "user_ll("%1", "%3")" \n"
" bne %1, %z4, 3f \n"
" .set pop \n"
" move $1, %z5 \n"
" .set "MIPS_ISA_ARCH_LEVEL" \n"
"2: "user_sc("$1", "%2")" \n"
" beqz $1, 1b \n"
"3: " __SYNC_ELSE(full, loongson3_war, __WEAK_LLSC_MB) "\n"
" .insn \n"
" .set pop \n"
" .section .fixup,\"ax\" \n"
"4: li %0, %6 \n"
" j 3b \n"
" .previous \n"
" .section __ex_table,\"a\" \n"
" "__UA_ADDR "\t1b, 4b \n"
" "__UA_ADDR "\t2b, 4b \n"
" .previous
Signed-off-by: Lichao Liu <liulichao@loongson.cn>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
2984b3f8c2