Re: [RFC PATCH 3/7] static_call: use helper to access non-exported key

From
Peter Zijlstra <peterz@infradead.org>
Date
2021-11-09 19:42:47
Also in
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Reply to
Ard Biesheuvel, 2021-11-09
On Tue, Nov 09, 2021 at 07:54:23PM +0100, Ard Biesheuvel wrote:
On Tue, 9 Nov 2021 at 19:53, Peter Zijlstra [off-list ref] wrote:
quoted
On Tue, Nov 09, 2021 at 05:45:45PM +0100, Ard Biesheuvel wrote:
quoted
@@ -196,13 +190,21 @@ extern long __static_call_return0(void);
      EXPORT_SYMBOL_GPL(STATIC_CALL_KEY(name));                       \
      EXPORT_SYMBOL_GPL(STATIC_CALL_TRAMP(name))

+#define EXPORT_STATIC_CALL_GETKEY_HELPER(name)                               \
+     struct static_call_key *STATIC_CALL_GETKEY(name)(void) {        \
+             BUG_ON(!core_kernel_text(                               \
+                     (unsigned long)__builtin_return_address(0)));   \
+             return &STATIC_CALL_KEY(name);                          \
+     }                                                               \
+     EXPORT_SYMBOL_GPL(STATIC_CALL_GETKEY(name))
So if I were a nevarious module, I would look up the above symbol from
kallsyms (it is exported and easily obtainable) and then simply
read the text to discover the key address and we're in business.
Yeah I realised that. So would you prefer to have a
.static_call_tramp_key section in each module and look up the keys in
the module loader?
Think so... do you actually have a need for this?

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Thread (22 messages) 22 messages, 2 authors, last reply 2021-11-09
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