Re: [PATCH v6 4/8] module: prepare to handle ROX allocations for text
From: Luis Chamberlain <mcgrof@kernel.org>
Date: 2024-10-19 22:30:44
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On Wed, Oct 16, 2024 at 03:24:20PM +0300, Mike Rapoport wrote:
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org> In order to support ROX allocations for module text, it is necessary to handle modifications to the code, such as relocations and alternatives patching, without write access to that memory. One option is to use text patching, but this would make module loading extremely slow and will expose executable code that is not finally formed. A better way is to have memory allocated with ROX permissions contain invalid instructions and keep a writable, but not executable copy of the module text. The relocations and alternative patches would be done on the writable copy using the addresses of the ROX memory. Once the module is completely ready, the updated text will be copied to ROX memory using text patching in one go and the writable copy will be freed. Add support for that to module initialization code and provide necessary interfaces in execmem. Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewd-by: Luis Chamberlain [off-list ref] Luis