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| author | Thomas Gleixner <tglx@linutronix.de> | 2023-10-17 23:23:31 +0200 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-10-18 18:28:41 +0200 |
| commit | 4c585af7180c147062c636a927a2fc2b6a7072f5 (patch) | |
| tree | c7c48c6d1f897e7cd9161288cd342235c98d39b5 /arch/x86/include/asm/microcode.h | |
| parent | x86/microcode: Provide CONFIG_MICROCODE_INITRD32 (diff) | |
| download | linux-4c585af7180c147062c636a927a2fc2b6a7072f5.tar.xz linux-4c585af7180c147062c636a927a2fc2b6a7072f5.zip | |
x86/boot/32: Temporarily map initrd for microcode loading
Early microcode loading on 32-bit runs in physical address mode because
the initrd is not covered by the initial page tables. That results in
a horrible mess all over the microcode loader code.
Provide a temporary mapping for the initrd in the initial page tables by
appending it to the actual initial mapping starting with a new PGD or
PMD depending on the configured page table levels ([non-]PAE).
The page table entries are located after _brk_end so they are not
permanently using memory space. The mapping is invalidated right away in
i386_start_kernel() after the early microcode loader has run.
This prepares for removing the physical address mode oddities from all
over the microcode loader code, which in turn allows further cleanups.
Provide the map and unmap code and document the place where the
microcode loader needs to be invoked with a comment.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231017211722.292291436@linutronix.de
Diffstat (limited to 'arch/x86/include/asm/microcode.h')
| -rw-r--r-- | arch/x86/include/asm/microcode.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h index bbbe9d744977..5216bf1acc3b 100644 --- a/arch/x86/include/asm/microcode.h +++ b/arch/x86/include/asm/microcode.h @@ -23,6 +23,8 @@ static inline void load_ucode_ap(void) { } static inline void microcode_bsp_resume(void) { } #endif +extern unsigned long initrd_start_early; + #ifdef CONFIG_CPU_SUP_INTEL /* Intel specific microcode defines. Public for IFS */ struct microcode_header_intel { |