On 4/9/13, Vijay Singh <vijju.si...@gmail.com> wrote:
> Hi, I was looking for some help with copyinstr() on an amd64 platform.
>
> My from address happens to be in the kernel (stack). I am getting an
> EFAULT, and I am wondering how to fix that.
>
> Would using memory from malloc() make a difference?
The copyinstr check the address before do anything.
amd64/support.S:
/*
* copyinstr(from, to, maxlen, int *lencopied) - MP SAFE
* %rdi, %rsi, %rdx, %rcx
*
* copy a string from from to to, stop when a 0 character is reached.
* return ENAMETOOLONG if string is longer than maxlen, and
* EFAULT on protection violations. If lencopied is non-zero,
* return the actual length in *lencopied.
*/
ENTRY(copyinstr)
movq %rdx,%r8 /* %r8 = maxlen */
movq %rcx,%r9 /* %r9 = *len */
xchgq %rdi,%rsi /* %rdi = from, %rsi = to */
movq PCPU(CURPCB),%rcx
movq $cpystrflt,PCB_ONFAULT(%rcx)
movq $VM_MAXUSER_ADDRESS,%rax
/* make sure 'from' is within bounds */
subq %rsi,%rax
jbe cpystrfl
[...]
cpystrflt:
movq $EFAULT,%rax
[...]
Try copyout() instead of copyinstr(), as there in amd64 are no copyoutstr().
>
> -vijay
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