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Having a list of alternatives to check with a per-entry function pointer to a check function is nice style-wise. But in case of early-alternatives it can clash with the non-relocated kernel and the function pointer in the list pointing to a completely wrong location. This isn't an issue with one or two list entries, as in that case the compiler seems to unroll the loop and even usage of the list structure and then only does relative jumps into the check functions based on this. When adding a third entry to either list though, the issue that was hiding there from the beginning is triggered resulting a jump to a memory address that isn't part of the kernel at all. The list of features/erratas only contained an unused name and the pointer to the check function, so an easy solution for the problem is to just unroll the loop in code, dismantle the whole list structure and just call the relevant check functions one by one ourself. For the T-Head errata this includes moving the stage-check inside the check functions. The issue is only relevant for things that might be called for early- alternatives (T-Head and possible future main extensions), so the SiFive erratas were not affected from the beginning, as they got an early return for early-alternatives in the original patchset. Signed-off-by: Heiko Stuebner <heiko@sntech.de> Tested-by: Samuel Holland <samuel@sholland.org> Link: https://lore.kernel.org/r/20220526205646.258337-6-heiko@sntech.de Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> |
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