Messages in this thread | | | Date | Mon, 5 Nov 2018 21:28:29 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH v3 2/7] x86/jump_label: Use text_poke_early() during early_init |
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On Mon, 5 Nov 2018, Andy Lutomirski wrote: > On Mon, Nov 5, 2018 at 11:25 AM Nadav Amit <namit@vmware.com> wrote: > Linus, hpa, or Dave, a question for you: suppose I map some page > writably, write to it, then upgrade permissions to allow execute. > Must I force all CPUs that might execute from it without first > serializing to serialize? I suspect this doesn't really affect user > code, but it may affect the module loader. > > To be safe, shouldn't the module loader broadcast an IPI to > sync_core() everywhere after loading a module and before making it > runnable, regardless of alternative patching? > > IOW, the right sequence of events probably ought to me: > > 1. Allocate the memory and map it. > 2. Copy in the text. > 3. Patch alternatives, etc. This is logically just like (2) from an > architectural perspective -- we're just writing to memory that won't > be executed. > 4. Serialize everything. > 5. Run it!
I'd make that:
1. Allocate the memory and map it RW 2. Copy in the text. 3. Patch alternatives, etc. This is logically just like (2) from an architectural perspective -- we're just writing to memory that won't be executed. 4. Map it RX 5. Serialize everything. 6. Run it!
Thanks,
tglx
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