Messages in this thread |  | | Date | Wed, 23 Oct 2013 14:20:47 -0400 | From | David Long <> | Subject | Re: [PATCH v2 05/13] uprobes: add arch write opcode hook |
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On 10/19/13 12:50, Oleg Nesterov wrote: > On 10/15, David Long wrote: >> >> Allow arches to write the opcode with a custom function. ARM needs to >> customize the swbp instruction depending on the condition code of the >> instruction it replaces. > > Well, we already have "__weak set_swbp(auprobe, ...)", can't arm use it? > > If not, > >> +void __weak arch_uprobe_write_opcode(struct arch_uprobe *auprobe, void *vaddr, >> + uprobe_opcode_t opcode) >> +{ >> + memcpy(vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); >> +} >> ... >> - copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); >> + vaddr_new = kmap_atomic(new_page); >> + arch_uprobe_write_opcode(auprobe, vaddr_new + (vaddr & ~PAGE_MASK), >> + opcode); >> + kunmap_atomic(vaddr_new); > > Again, if you need to add the new __weak helper, I think it should simply > do copy_to_page(). > > Oleg. >
Unfortunately, providing an alternative set_swbp() would mean duplicating a moderate chunk of code from kernel/uprobes.c. Adding arch_uprobe_write_opcode() feels a little more like the right thing to do to me. I notice there don't seem to be any alternative set_swbp functions in the (rc6) kernel tree. I will adjust the arch_uprobe_write_opcode imlementation as suggested.
-dl
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