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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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0a637ee612
We currently allow invocation of 8 boot services with efi_call_early(). Not included are LocateHandleBuffer and LocateProtocol in particular. For graphics output or to retrieve PCI ROMs and Apple device properties, we're thus forced to use the LocateHandle + AllocatePool + LocateHandle combo, which is cumbersome and needs more code. The ARM folks allow invocation of the full set of boot services but are restricted to our 8 boot services in functions shared across arches. Thus, rather than adding just LocateHandleBuffer and LocateProtocol to struct efi_config, let's rework efi_call_early() to allow invocation of arbitrary boot services by selecting the 64 bit vs 32 bit code path in the macro itself. When compiling for 32 bit or for 64 bit without mixed mode, the unused code path is optimized away and the binary code is the same as before. But on 64 bit with mixed mode enabled, this commit adds one compare instruction to each invocation of a boot service and, depending on the code path selected, two jump instructions. (Most of the time gcc arranges the jumps in the 32 bit code path.) The result is a minuscule performance penalty and the binary code becomes slightly larger and more difficult to read when disassembled. This isn't a hot path, so these drawbacks are arguably outweighed by the attainable simplification of the C code. We have some overhead anyway for thunking or conversion between calling conventions. The 8 boot services can consequently be removed from struct efi_config. No functional change intended (for now). Example -- invocation of free_pool before (64 bit code path): 0x2d4 movq %ds:efi_early, %rdx ; efi_early 0x2db movq %ss:arg_0-0x20(%rsp), %rsi 0x2e0 xorl %eax, %eax 0x2e2 movq %ds:0x28(%rdx), %rdi ; efi_early->free_pool 0x2e6 callq *%ds:0x58(%rdx) ; efi_early->call() Example -- invocation of free_pool after (64 / 32 bit mixed code path): 0x0dc movq %ds:efi_early, %rax ; efi_early 0x0e3 cmpb $0, %ds:0x28(%rax) ; !efi_early->is64 ? 0x0e7 movq %ds:0x20(%rax), %rdx ; efi_early->call() 0x0eb movq %ds:0x10(%rax), %rax ; efi_early->boot_services 0x0ef je $0x150 0x0f1 movq %ds:0x48(%rax), %rdi ; free_pool (64 bit) 0x0f5 xorl %eax, %eax 0x0f7 callq *%rdx ... 0x150 movl %ds:0x30(%rax), %edi ; free_pool (32 bit) 0x153 jmp $0x0f5 Size of eboot.o text section: CONFIG_X86_32: 6464 before, 6318 after CONFIG_X86_64 && !CONFIG_EFI_MIXED: 7670 before, 7573 after CONFIG_X86_64 && CONFIG_EFI_MIXED: 7670 before, 8319 after Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> |
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| .. | ||
| boot | ||
| configs | ||
| crypto | ||
| entry | ||
| events | ||
| ia32 | ||
| include | ||
| kernel | ||
| kvm | ||
| lguest | ||
| lib | ||
| math-emu | ||
| mm | ||
| net | ||
| oprofile | ||
| pci | ||
| platform | ||
| power | ||
| purgatory | ||
| ras | ||
| realmode | ||
| tools | ||
| um | ||
| video | ||
| xen | ||
| .gitignore | ||
| Kbuild | ||
| Kconfig | ||
| Kconfig.cpu | ||
| Kconfig.debug | ||
| Makefile | ||
| Makefile_32.cpu | ||
| Makefile.um | ||