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x86/kexec: Drop page_list argument from relocate_kernel()

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The kernel's virtual mapping of the relocate_kernel page currently needs
to be RWX because it is written to before the %cr3 switch.

Now that the relocate_kernel page has its own .data section and local
variables, it can also have *global* variables. So eliminate the separate
page_list argument, and write the same information directly to variables
in the relocate_kernel page instead. This way, the relocate_kernel code
itself doesn't need to copy it.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lore.kernel.org/r/20241205153343.3275139-11-dwmw2@infradead.org
This commit is contained in:
David Woodhouse 2024-12-05 15:05:16 +00:00 committed by Ingo Molnar
parent 8dbec5c77b
commit b3adabae8a
3 changed files with 24 additions and 42 deletions
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12
arch/x86/include/asm/kexec.h
View File

@ -8,12 +8,6 @@
# define PA_PGD 2
# define PA_SWAP_PAGE 3
# define PAGES_NR 4
#else
# define PA_CONTROL_PAGE 0
# define VA_CONTROL_PAGE 1
# define PA_TABLE_PAGE 2
# define PA_SWAP_PAGE 3
# define PAGES_NR 4
#endif
# define KEXEC_CONTROL_PAGE_SIZE 4096
@ -60,6 +54,10 @@ struct kimage;
/* The native architecture */
# define KEXEC_ARCH KEXEC_ARCH_X86_64
extern unsigned long kexec_va_control_page;
extern unsigned long kexec_pa_table_page;
extern unsigned long kexec_pa_swap_page;
#endif
/*
@ -122,7 +120,7 @@ relocate_kernel(unsigned long indirection_page,
#else
unsigned long
relocate_kernel(unsigned long indirection_page,
unsigned long page_list,
unsigned long pa_control_page,
unsigned long start_address,
unsigned int preserve_context,
unsigned int host_mem_enc_active);

18
arch/x86/kernel/machine_kexec_64.c
View File

@ -315,6 +315,11 @@ int machine_kexec_prepare(struct kimage *image)
result = init_pgtable(image, __pa(control_page));
if (result)
return result;
kexec_va_control_page = (unsigned long)control_page;
kexec_pa_table_page = (unsigned long)__pa(image->arch.pgd);
if (image->type == KEXEC_TYPE_DEFAULT)
kexec_pa_swap_page = page_to_pfn(image->swap_page) << PAGE_SHIFT;
__memcpy(control_page, __relocate_kernel_start, reloc_end - reloc_start);
@ -339,12 +344,11 @@ void machine_kexec_cleanup(struct kimage *image)
void machine_kexec(struct kimage *image)
{
unsigned long (*relocate_kernel_ptr)(unsigned long indirection_page,
unsigned long page_list,
unsigned long pa_control_page,
unsigned long start_address,
unsigned int preserve_context,
unsigned int host_mem_enc_active);
unsigned long reloc_start = (unsigned long)__relocate_kernel_start;
unsigned long page_list[PAGES_NR];
unsigned int host_mem_enc_active;
int save_ftrace_enabled;
void *control_page;
@ -382,14 +386,6 @@ void machine_kexec(struct kimage *image)
control_page = page_address(image->control_code_page);
page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
page_list[PA_TABLE_PAGE] = (unsigned long)__pa(image->arch.pgd);
if (image->type == KEXEC_TYPE_DEFAULT)
page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
<< PAGE_SHIFT);
/*
* Allow for the possibility that relocate_kernel might not be at
* the very start of the page.
@ -417,7 +413,7 @@ void machine_kexec(struct kimage *image)
/* now call it */
image->start = relocate_kernel_ptr((unsigned long)image->head,
(unsigned long)page_list,
virt_to_phys(control_page),
image->start,
image->preserve_context,
host_mem_enc_active);

36
arch/x86/kernel/relocate_kernel_64.S
View File

@ -34,9 +34,9 @@ SYM_DATA_LOCAL(saved_cr0, .quad 0)
SYM_DATA_LOCAL(saved_cr3, .quad 0)
SYM_DATA_LOCAL(saved_cr4, .quad 0)
/* other data */
SYM_DATA_LOCAL(va_control_page, .quad 0)
SYM_DATA_LOCAL(pa_table_page, .quad 0)
SYM_DATA_LOCAL(pa_swap_page, .quad 0)
SYM_DATA(kexec_va_control_page, .quad 0)
SYM_DATA(kexec_pa_table_page, .quad 0)
SYM_DATA(kexec_pa_swap_page, .quad 0)
SYM_DATA_LOCAL(pa_backup_pages_map, .quad 0)
.section .text.relocate_kernel,"ax";
@ -46,7 +46,7 @@ SYM_CODE_START_NOALIGN(relocate_kernel)
ANNOTATE_NOENDBR
/*
* %rdi indirection_page
* %rsi page_list
* %rsi pa_control_page
* %rdx start address
* %rcx preserve_context
* %r8 host_mem_enc_active
@ -79,31 +79,19 @@ SYM_CODE_START_NOALIGN(relocate_kernel)
/* Save SME active flag */
movq %r8, %r12
/*
* get physical and virtual address of control page now
* this is impossible after page table switch
*/
movq PTR(PA_CONTROL_PAGE)(%rsi), %r8
movq PTR(VA_CONTROL_PAGE)(%rsi), %r11
/* get physical address of page table now too */
movq PTR(PA_TABLE_PAGE)(%rsi), %r9
/* get physical address of swap page now */
movq PTR(PA_SWAP_PAGE)(%rsi), %r10
/* save some information for jumping back */
movq %r9, pa_table_page(%rip)
movq %r10, pa_swap_page(%rip)
/* save indirection list for jumping back */
movq %rdi, pa_backup_pages_map(%rip)
movq %r11, va_control_page(%rip)
/* Save the preserve_context to %r11 as swap_pages clobbers %rcx. */
movq %rcx, %r11
/* Switch to the identity mapped page tables */
movq kexec_pa_table_page(%rip), %r9
movq %r9, %cr3
/* Physical address of control page */
movq %rsi, %r8
/* setup a new stack at the end of the physical control page */
lea PAGE_SIZE(%r8), %rsp
@ -227,13 +215,13 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped)
/* get the re-entry point of the peer system */
movq 0(%rsp), %rbp
leaq relocate_kernel(%rip), %r8
movq pa_swap_page(%rip), %r10
movq kexec_pa_swap_page(%rip), %r10
movq pa_backup_pages_map(%rip), %rdi
movq pa_table_page(%rip), %rax
movq kexec_pa_table_page(%rip), %rax
movq %rax, %cr3
lea PAGE_SIZE(%r8), %rsp
call swap_pages
movq va_control_page(%rip), %rax
movq kexec_va_control_page(%rip), %rax
addq $(virtual_mapped - relocate_kernel), %rax
pushq %rax
ANNOTATE_UNRET_SAFE