diff options
| author | Nathan Chancellor <nathan@kernel.org> | 2025-01-09 14:04:17 +0000 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2025-01-14 13:00:18 +0100 |
| commit | eeed9150411a63dd0611490cf31fdae681427918 (patch) | |
| tree | 0df0332c3b7c451fd9d734ef408b2c814367b9b5 | |
| parent | 2cacf7f23a024ab1fdc603ca6a4f4c8b2de9f64e (diff) | |
x86/kexec: Fix location of relocate_kernel with -ffunction-sections
After commit
cb33ff9e063c ("x86/kexec: Move relocate_kernel to kernel .data section"),
kernels configured with an option that uses -ffunction-sections, such as
CONFIG_LTO_CLANG, crash when kexecing because the value of relocate_kernel
does not match the value of __relocate_kernel_start so incorrect code gets
copied via machine_kexec_prepare().
$ llvm-nm good-vmlinux &| rg relocate_kernel
ffffffff83280d41 T __relocate_kernel_end
ffffffff83280b00 T __relocate_kernel_start
ffffffff83280b00 T relocate_kernel
$ llvm-nm bad-vmlinux &| rg relocate_kernel
ffffffff83266100 D __relocate_kernel_end
ffffffff83266100 D __relocate_kernel_start
ffffffff8120b0d8 T relocate_kernel
When -ffunction-sections is enabled, TEXT_MAIN matches on
'.text.[0-9a-zA-Z_]*' to coalesce the function specific functions back
into .text during link time after they have been optimized. Due to the
placement of TEXT_TEXT before KEXEC_RELOCATE_KERNEL in the x86 linker
script, the .text.relocate_kernel section ends up in .text instead of
.data.
Use a second dot in the relocate_kernel section name to avoid matching
on TEXT_MAIN, which matches a similar situation that happened in
commit
79cd2a11224e ("x86/retpoline,kprobes: Fix position of thunk sections with CONFIG_LTO_CLANG"),
which allows kexec to function properly.
While .data.relocate_kernel still ends up in the .data section via
DATA_MAIN -> DATA_DATA, ensure it is located with the
.text.relocate_kernel section as intended by performing the same
transformation.
Fixes: cb33ff9e063c ("x86/kexec: Move relocate_kernel to kernel .data section")
Fixes: 8dbec5c77bc3 ("x86/kexec: Add data section to relocate_kernel")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250109140757.2841269-6-dwmw2@infradead.org
| -rw-r--r-- | arch/x86/kernel/relocate_kernel_64.S | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/vmlinux.lds.S | 4 |
2 files changed, 5 insertions, 5 deletions
diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S index a95691b42c5c..14ed40b7f322 100644 --- a/arch/x86/kernel/relocate_kernel_64.S +++ b/arch/x86/kernel/relocate_kernel_64.S @@ -23,11 +23,11 @@ #define PAGE_ATTR (_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY) /* - * The .text.relocate_kernel and .data.relocate_kernel sections are copied + * The .text..relocate_kernel and .data..relocate_kernel sections are copied * into the control page, and the remainder of the page is used as the stack. */ - .section .data.relocate_kernel,"a"; + .section .data..relocate_kernel,"a"; /* Minimal CPU state */ SYM_DATA_LOCAL(saved_rsp, .quad 0) SYM_DATA_LOCAL(saved_cr0, .quad 0) @@ -39,7 +39,7 @@ 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"; + .section .text..relocate_kernel,"ax"; .code64 SYM_CODE_START_NOALIGN(relocate_kernel) UNWIND_HINT_END_OF_STACK diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 0c893997f023..63ff60a11be5 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -100,8 +100,8 @@ const_pcpu_hot = pcpu_hot; #define KEXEC_RELOCATE_KERNEL \ . = ALIGN(0x100); \ __relocate_kernel_start = .; \ - *(.text.relocate_kernel); \ - *(.data.relocate_kernel); \ + *(.text..relocate_kernel); \ + *(.data..relocate_kernel); \ __relocate_kernel_end = .; ASSERT(__relocate_kernel_end - __relocate_kernel_start <= KEXEC_CONTROL_CODE_MAX_SIZE, |