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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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0154416a71
Implement the transition code to go from IA32e mode to protected mode in the EFI boot stub. This is required to use 32-bit EFI services from a 64-bit kernel. Since EFI boot stub is executed in an identity-mapped region, there's not much we need to do before invoking the 32-bit EFI boot services. However, we do reload the firmware's global descriptor table (efi32_boot_gdt) in case things like timer events are still running in the firmware. Signed-off-by: Matt Fleming <matt.fleming@intel.com>
31 lines
540 B
ArmAsm
31 lines
540 B
ArmAsm
#include <asm/segment.h>
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#include <asm/msr.h>
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#include <asm/processor-flags.h>
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#include "../../platform/efi/efi_stub_64.S"
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#ifdef CONFIG_EFI_MIXED
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.code64
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.text
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ENTRY(efi64_thunk)
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push %rbp
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push %rbx
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subq $16, %rsp
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leaq efi_exit32(%rip), %rax
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movl %eax, 8(%rsp)
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leaq efi_gdt64(%rip), %rax
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movl %eax, 4(%rsp)
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movl %eax, 2(%rax) /* Fixup the gdt base address */
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leaq efi32_boot_gdt(%rip), %rax
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movl %eax, (%rsp)
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call __efi64_thunk
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addq $16, %rsp
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pop %rbx
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pop %rbp
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ret
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ENDPROC(efi64_thunk)
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#endif /* CONFIG_EFI_MIXED */
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