efi/x86: Don't map the entire kernel text RW for mixed mode
The mixed mode thunking routine requires a part of it to be mapped 1:1, and for this reason, we currently map the entire kernel .text read/write in the EFI page tables, which is bad. In fact, the kernel_map_pages_in_pgd() invocation that installs this mapping is entirely redundant, since all of DRAM is already 1:1 mapped read/write in the EFI page tables when we reach this point, which means that .rodata is mapped read-write as well. So let's remap both .text and .rodata read-only in the EFI page tables. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200113172245.27925-6-ardb@kernel.org
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