Commit 84292fff authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86_build_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 build updates from Borislav Petkov:
 "Two x86 build fixes:

   - Fix the vmlinux size check on 64-bit along with adding useful
     clarifications on the topic (Arvind Sankar)

   - Remove -m16 workaround now that the GCC versions that need it are
     unsupported (Nick Desaulniers)"

* tag 'x86_build_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/build: Remove -m16 workaround for unsupported versions of GCC
  x86/build: Fix vmlinux size check on 64-bit
parents 8ba27ae3 2838307b

arch/x86/Makefile

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@@ -24,14 +24,7 @@ endif 


# How to compile the 16-bit code.  Note we always compile for -march=i386;

# that way we can complain to the user if the CPU is insufficient.

#

# The -m16 option is supported by GCC >= 4.9 and clang >= 3.5. For

# older versions of GCC, include an *assembly* header to make sure that

# gcc doesn't play any games behind our back.

CODE16GCC_CFLAGS := -m32 -Wa,$(srctree)/arch/x86/boot/code16gcc.h

M16_CFLAGS	 := $(call cc-option, -m16, $(CODE16GCC_CFLAGS))



REALMODE_CFLAGS	:= $(M16_CFLAGS) -g -Os -DDISABLE_BRANCH_PROFILING \

REALMODE_CFLAGS	:= -m16 -g -Os -DDISABLE_BRANCH_PROFILING \

		   -Wall -Wstrict-prototypes -march=i386 -mregparm=3 \

		   -fno-strict-aliasing -fomit-frame-pointer -fno-pic \

		   -mno-mmx -mno-sse

arch/x86/boot/code16gcc.h

deleted100644 → 0
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/* SPDX-License-Identifier: GPL-2.0 */

#

# code16gcc.h

#

# This file is added to the assembler via -Wa when compiling 16-bit C code.

# This is done this way instead via asm() to make sure gcc does not reorder

# things around us.

#

# gcc 4.9+ has a real -m16 option so we can drop this hack long term.

#



	.code16gcc

arch/x86/include/asm/page_32_types.h

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@@ -53,7 +53,13 @@ 
#define STACK_TOP_MAX		STACK_TOP



/*

 * Kernel image size is limited to 512 MB (see in arch/x86/kernel/head_32.S)

 * In spite of the name, KERNEL_IMAGE_SIZE is a limit on the maximum virtual

 * address for the kernel image, rather than the limit on the size itself. On

 * 32-bit, this is not a strict limit, but this value is used to limit the

 * link-time virtual address range of the kernel, and by KASLR to limit the

 * randomized address from which the kernel is executed. A relocatable kernel

 * can be loaded somewhat higher than KERNEL_IMAGE_SIZE as long as enough space

 * remains for the vmalloc area.

 */

#define KERNEL_IMAGE_SIZE	(512 * 1024 * 1024)

arch/x86/include/asm/page_64_types.h

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@@ -98,8 +98,10 @@ 
#define STACK_TOP_MAX		TASK_SIZE_MAX



/*

 * Maximum kernel image size is limited to 1 GiB, due to the fixmap living

 * in the next 1 GiB (see level2_kernel_pgt in arch/x86/kernel/head_64.S).

 * In spite of the name, KERNEL_IMAGE_SIZE is a limit on the maximum virtual

 * address for the kernel image, rather than the limit on the size itself.

 * This can be at most 1 GiB, due to the fixmap living in the next 1 GiB (see

 * level2_kernel_pgt in arch/x86/kernel/head_64.S).

 *

 * On KASLR use 1 GiB by default, leaving 1 GiB for modules once the

 * page tables are fully set up.

arch/x86/include/asm/pgtable_32.h

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@@ -57,19 +57,13 @@ do { \ 
#endif



/*

 * This is how much memory in addition to the memory covered up to

 * and including _end we need mapped initially.

 * We need:

 *     (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)

 *     (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)

 * This is used to calculate the .brk reservation for initial pagetables.

 * Enough space is reserved to allocate pagetables sufficient to cover all

 * of LOWMEM_PAGES, which is an upper bound on the size of the direct map of

 * lowmem.

 *

 * Modulo rounding, each megabyte assigned here requires a kilobyte of

 * memory, which is currently unreclaimed.

 *

 * This should be a multiple of a page.

 *

 * KERNEL_IMAGE_SIZE should be greater than pa(_end)

 * and small than max_low_pfn, otherwise will waste some page table entries

 * With PAE paging (PTRS_PER_PMD > 1), we allocate PTRS_PER_PGD == 4 pages for

 * the PMD's in addition to the pages required for the last level pagetables.

 */

#if PTRS_PER_PMD > 1

#define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)