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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