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SubjectRe: [PATCH 04/29] x86/livepatch: Validate __fentry__ location
On Wed, 23 Feb 2022 11:57:26 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -1578,7 +1578,23 @@ unsigned long ftrace_location_range(unsi
> */
> unsigned long ftrace_location(unsigned long ip)
> {
> - return ftrace_location_range(ip, ip);
> + struct dyn_ftrace *rec;
> + unsigned long offset;
> + unsigned long size;
> +
> + rec = lookup_rec(ip, ip);
> + if (!rec) {
> + if (!kallsyms_lookup_size_offset(ip, &size, &offset))
> + goto out;
> +
> + rec = lookup_rec(ip - offset, (ip - offset) + size);
> + }
> +

Please create a new function for this. Perhaps find_ftrace_location().

ftrace_location() is used to see if the address given is a ftrace
nop or not. This change will make it always return true.

-- Steve

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