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951bcae6c5
kallsyms is a directory of all the symbols in the vmlinux binary, and so creating it is somewhat of a chicken-and-egg problem, as its non-zero size affects the layout of the binary, and therefore the values of the symbols. For this reason, the kernel is linked more than once, and the first pass does not include any kallsyms data at all. For the linker to accept this, the symbol declarations describing the kallsyms metadata are emitted as having weak linkage, so they can remain unsatisfied. During the subsequent passes, the weak references are satisfied by the kallsyms metadata that was constructed based on information gathered from the preceding passes. Weak references lead to somewhat worse codegen, because taking their address may need to produce NULL (if the reference was unsatisfied), and this is not usually supported by RIP or PC relative symbol references. Given that these references are ultimately always satisfied in the final link, let's drop the weak annotation, and instead, provide fallback definitions in the linker script that are only emitted if an unsatisfied reference exists. While at it, drop the FRV specific annotation that these symbols reside in .rodata - FRV is long gone. Tested-by: Nick Desaulniers <ndesaulniers@google.com> # Boot Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Link: https://lkml.kernel.org/r/20230504174320.3930345-1-ardb%40kernel.org Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
26 lines
808 B
C
26 lines
808 B
C
/* SPDX-License-Identifier: GPL-2.0-only */
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#ifndef LINUX_KALLSYMS_INTERNAL_H_
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#define LINUX_KALLSYMS_INTERNAL_H_
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#include <linux/types.h>
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/*
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* These will be re-linked against their real values during the second link
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* stage. Preliminary values must be provided in the linker script using the
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* PROVIDE() directive so that the first link stage can complete successfully.
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*/
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extern const unsigned long kallsyms_addresses[];
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extern const int kallsyms_offsets[];
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extern const u8 kallsyms_names[];
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extern const unsigned int kallsyms_num_syms;
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extern const unsigned long kallsyms_relative_base;
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extern const char kallsyms_token_table[];
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extern const u16 kallsyms_token_index[];
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extern const unsigned int kallsyms_markers[];
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extern const u8 kallsyms_seqs_of_names[];
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#endif // LINUX_KALLSYMS_INTERNAL_H_
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