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Subject[PATCH] uprobes: Document xol_area and arch_uprobe->insn/ixol
On 11/11, Ingo Molnar wrote:
>
> * Oleg Nesterov <oleg@redhat.com> wrote:
>
> > On 11/11, Ingo Molnar wrote:
> > >
> > > You guys are changing code that reads like gobbledygook to people
> > > reading it for the first time.
> >
> > Not that I am trying to defense uprobes, but this is equally true for
> > any piece of kernel code, at least to me ;)
>
> I'm really not suggesting to do overly much - only for some minimal blurb
> like the scheduler has in most places:

OK. Let me try to make a first step to improve this a little bit...

How about the patch below? Srikar?


Subject: [PATCH] uprobes: Document xol_area and arch_uprobe->insn/ixol

Document xol_area and arch_uprobe.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
kernel/events/uprobes.c | 15 +++++++++++++++
1 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 51a7f53..b886a5e 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -73,6 +73,17 @@ struct uprobe {
struct inode *inode; /* Also hold a ref to inode */
loff_t offset;
unsigned long flags;
+
+ /*
+ * The generic code assumes that it has two members of unknown type
+ * owned by the arch-specific code:
+ *
+ * insn - copy_insn() saves the original instruction here for
+ * arch_uprobe_analyze_insn().
+ *
+ * ixol - potentially modified instruction to execute out of
+ * line, copied to xol_area by xol_get_insn_slot().
+ */
struct arch_uprobe arch;
};

@@ -86,6 +97,10 @@ struct return_instance {
};

/*
+ * Execute out of line area: anonymous executable mapping installed
+ * by the probed task to execute the copy of the original instruction
+ * mangled by set_swbp().
+ *
* On a breakpoint hit, thread contests for a slot. It frees the
* slot after singlestep. Currently a fixed number of slots are
* allocated.
--
1.5.5.1



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