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| author | Peter Zijlstra <peterz@infradead.org> | 2020-03-16 10:13:45 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-03-25 18:28:27 +0100 |
| commit | fc8bd77d6476d7733ace9e03093b4acaee6e0605 (patch) | |
| tree | 0adc3f8653612dcfa4748ff7be3c1dbd54041a37 | |
| parent | f0f70adb78108a0cbc321a07133cd78ea4f84699 (diff) | |
| download | lwn-fc8bd77d6476d7733ace9e03093b4acaee6e0605.tar.gz lwn-fc8bd77d6476d7733ace9e03093b4acaee6e0605.zip | |
x86/kexec: Use RIP relative addressing
Normally identity_mapped is not visible to objtool, due to:
arch/x86/kernel/Makefile:OBJECT_FILES_NON_STANDARD_relocate_kernel_$(BITS).o := y
However, when we want to run objtool on vmlinux.o there is no hiding
it:
vmlinux.o: warning: objtool: .text+0x4c0f1: unsupported intra-function call
Replace the (i386 inspired) pattern:
call 1f
1: popq %r8
subq $(1b - relocate_kernel), %r8
With a x86_64 RIP-relative LEA:
leaq relocate_kernel(%rip), %r8
Suggested-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200324160924.143334345@infradead.org
| -rw-r--r-- | arch/x86/kernel/relocate_kernel_64.S | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S index ef3ba99068d3..cc5c8b9048b5 100644 --- a/arch/x86/kernel/relocate_kernel_64.S +++ b/arch/x86/kernel/relocate_kernel_64.S @@ -196,10 +196,7 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) /* get the re-entry point of the peer system */ movq 0(%rsp), %rbp - call 1f -1: - popq %r8 - subq $(1b - relocate_kernel), %r8 + leaq relocate_kernel(%rip), %r8 movq CP_PA_SWAP_PAGE(%r8), %r10 movq CP_PA_BACKUP_PAGES_MAP(%r8), %rdi movq CP_PA_TABLE_PAGE(%r8), %rax |