Hi experts: an user application generates a un-alignment data abort, then
in function do_alignment, kernel read the instruction from the address where
data abort occurs by: fault = __get_user(instr, (u32 *)instrptr); after
this sentence, instr is the error instruction that generate data abort. i
change this instruction from strict alignment check instruction to not strict
alignmentcheck instruction by: instr = instr&030; at last i write this
instruction back to ram, and let cpu execute this instruction again:
*((u32*)instrptr) = instr; it works on kernel 2.6.35, but on version 3.0, it
failed, the last sentence above generates a Oops: [ 58.966552] Unable to
handle kernel paging request at virtual address 000084ec
[ 58.974029] pgd = db9f4000
[ 58.976806] [000084ec] *pgd=1b9db831, *pte=0ae5f59f, *ppte=0ae5fe7e
[ 58.986877] Internal error: Oops: 81f [#1] PREEMPT SMP 1. it seems that
kernel 3.0 can not modify user mode program instructions directly even underSVC
mode. 2. how can i change the page permisson before write back instruction of
user mode application? for example, find out the page tables of current
application, find out the pte which representsthe instruction that generate
data abort, then modify pte, write back instruction, restore pte, done. how
to do these? please advise, thanks very much. Best Regards
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