Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1705569
| From | "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCHv3 05/13] x86/boot/compressed/64: Detect and handle 5-level paging at boot-time |
| Date | 2017-08-07 16:20 +0200 |
| Message-ID | <ubR2X-W5-61@gated-at.bofh.it> (permalink) |
| References | <ubR2V-W5-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
This patch prepare decompression code to boot-time switching between 4- and 5-level paging. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> --- arch/x86/boot/compressed/head_64.S | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index fbf4c32d0b62..2e362aea3319 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -347,6 +347,28 @@ preferred_addr: leaq boot_stack_end(%rbx), %rsp #ifdef CONFIG_X86_5LEVEL + /* Preserve rbx across cpuid */ + movq %rbx, %r8 + + /* Check if leaf 7 is supported */ + movl $0, %eax + cpuid + cmpl $7, %eax + jb lvl5 + + /* + * Check if la57 is supported. + * The feature is enumerated with CPUID.(EAX=07H, ECX=0):ECX[bit 16] + */ + movl $7, %eax + movl $0, %ecx + cpuid + andl $(1 << 16), %ecx + jz lvl5 + + /* Restore rbx */ + movq %r8, %rbx + /* Check if 5-level paging has already enabled */ movq %cr4, %rax testl $X86_CR4_LA57, %eax @@ -386,6 +408,8 @@ preferred_addr: pushq %rax lretq lvl5: + /* Restore rbx */ + movq %r8, %rbx #endif /* Zero EFLAGS */ -- 2.13.2
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCHv3 00/13] Boot-time switching between 4- and 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-08-07 16:20 +0200 [PATCHv3 09/13] x86/mm: Fold p4d page table layer at runtime "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-08-07 16:20 +0200 [PATCHv3 01/13] mm, sparsemem: Allocate mem_section at runtime for SPARSEMEM_EXTREME "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-08-07 16:20 +0200 [PATCHv3 05/13] x86/boot/compressed/64: Detect and handle 5-level paging at boot-time "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-08-07 16:20 +0200 [PATCHv3 04/13] x86/xen: Drop 5-level paging support code from XEN_PV code "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-08-07 16:20 +0200
csiph-web