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linux-next/arch/x86/boot
Lukas Wunner 0a637ee612 x86/efi: Allow invocation of arbitrary boot services
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>
2016-09-09 16:08:57 +01:00
..
compressed x86/efi: Allow invocation of arbitrary boot services 2016-09-09 16:08:57 +01:00
tools x86/boot: Remove unused 'is_big_kernel' variable 2016-02-16 09:16:58 +01:00
.gitignore x86: remove offsets.h from .gitignore and dontdiff 2012-11-19 14:10:53 +01:00
a20.c x86, setup: "glove box" BIOS interrupts in the core boot code 2009-04-09 16:08:11 -07:00
apm.c x86, setup: "glove box" BIOS interrupts in the APM code 2009-04-09 16:08:11 -07:00
bioscall.S x86, boot: Move intcall() to the .inittext section 2014-01-04 14:29:08 -08:00
bitops.h x86, asm: use bool for bitops and other assembly outputs 2016-06-08 12:41:20 -07:00
boot.h Merge branch 'x86/asm' into x86/mm, to resolve conflicts 2016-07-15 10:26:04 +02:00
cmdline.c x86, boot: Pass cmd_line_ptr with unsigned long instead 2013-01-29 15:26:09 -08:00
code16gcc.h x86, build: Change code16gcc.h from a C header to an assembly header 2014-06-04 13:16:48 -07:00
copy.S x86, boot: Use .code16 instead of .code16gcc 2014-01-04 13:59:06 -08:00
cpu.c x86/mm: Disallow running with 32-bit PTEs to work around erratum 2016-07-13 09:43:25 +02:00
cpucheck.c x86/mm: Disallow running with 32-bit PTEs to work around erratum 2016-07-13 09:43:25 +02:00
cpuflags.c x86/mm: Disallow running with 32-bit PTEs to work around erratum 2016-07-13 09:43:25 +02:00
cpuflags.h x86/mm: Disallow running with 32-bit PTEs to work around erratum 2016-07-13 09:43:25 +02:00
ctype.h x86, setup: Rename BOOT_ISDIGIT_H to BOOT_CTYPE_H 2015-01-13 11:59:04 +01:00
early_serial_console.c x86/boot: Add missing file header comments 2016-05-10 10:12:03 +02:00
edd.c x86, boot: Create a separate string.h file to provide standard string functions 2014-03-19 15:43:45 -07:00
header.S x86/boot: Calculate decompression size during boot not build 2016-04-29 11:03:29 +02:00
install.sh kbuild: use INSTALLKERNEL to select customized installkernel script 2009-09-20 12:18:14 +02:00
main.c x86/boot: Obsolete the MCA sys_desc_table 2015-07-21 10:55:11 +02:00
Makefile Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-08-02 16:37:12 -04:00
memory.c x86, setup: When probing memory with e801, use ax/bx as a pair 2011-04-25 14:52:37 -07:00
mkcpustr.c x86/cpufeature: Carve out X86_FEATURE_* 2016-01-30 11:22:17 +01:00
mtools.conf.in i386: move boot 2007-10-11 11:16:45 +02:00
pm.c x86: remove zImage support 2009-03-11 11:00:00 -07:00
pmjump.S x86, setup: move 32-bit code to .text32 2009-03-17 15:26:06 -07:00
printf.c x86/boot: Fix a sanity check in printf.c 2013-08-14 11:48:41 +02:00
regs.c x86, boot: Create a separate string.h file to provide standard string functions 2014-03-19 15:43:45 -07:00
setup.ld x86, boot: Define the 2.12 bzImage boot protocol 2013-01-27 15:56:37 -08:00
string.c x86, asm: use bool for bitops and other assembly outputs 2016-06-08 12:41:20 -07:00
string.h x86, boot: Move memcmp() into string.h and string.c 2014-03-19 15:44:04 -07:00
tty.c x86, setup: reorganize the early console setup 2010-08-02 15:51:56 -07:00
version.c kbuild: move utsrelease.h to include/generated 2009-12-12 13:08:15 +01:00
vesa.h x86-boot: don't request VBE2 information 2008-03-07 16:39:14 +01:00
video-bios.c x86: fix usage of bios intcall() 2009-07-04 12:56:32 -07:00
video-mode.c x86/mm: Fix regression with huge pages on PAE 2015-12-04 09:14:27 +01:00
video-vesa.c x86, boot: Create a separate string.h file to provide standard string functions 2014-03-19 15:43:45 -07:00
video-vga.c x86, setup: Set ax register in boot vga query 2010-06-10 15:24:29 -07:00
video.c x86/mm: Fix regression with huge pages on PAE 2015-12-04 09:14:27 +01:00
video.h x86/boot/video: Move the 'video_segment' variable to video.c 2015-02-19 00:25:05 +01:00