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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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0e0ed6406e
Module CRCs are implemented as absolute symbols that get resolved by
a linker script. We build an intermediate .o that contains an
unresolved symbol for each CRC. genksysms parses this .o, calculates
the CRCs and writes a linker script that "resolves" the symbols to
the calculated CRC.
Unfortunately the ppc64 relocatable kernel sees these CRCs as symbols
that need relocating and relocates them at boot. Commit d4703aef
(module: handle ppc64 relocating kcrctabs when CONFIG_RELOCATABLE=y)
added a hook to reverse the bogus relocations. Part of this patch
created a symbol at 0x0:
# head -2 /proc/kallsyms
0000000000000000 T reloc_start
c000000000000000 T .__start
This reloc_start symbol is causing lots of confusion to perf. It
thinks reloc_start is a massive function that stretches from 0x0 to
0xc000000000000000 and we get various cryptic errors out of perf,
including:
problem incrementing symbol count, skipping event
This patch removes the reloc_start linker script label and instead
defines it as PHYSICAL_START. We also need to wrap it with
CONFIG_PPC64 because the ppc32 kernel can set a non zero
PHYSICAL_START at compile time and we wouldn't want to subtract
it from the CRCs in that case.
Signed-off-by: Anton Blanchard <anton@samba.org>
Cc: <stable@kernel.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
91 lines
2.3 KiB
C
91 lines
2.3 KiB
C
#ifndef _ASM_POWERPC_MODULE_H
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#define _ASM_POWERPC_MODULE_H
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#ifdef __KERNEL__
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/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/list.h>
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#include <asm/bug.h>
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#include <asm-generic/module.h>
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#ifndef __powerpc64__
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/*
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* Thanks to Paul M for explaining this.
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*
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* PPC can only do rel jumps += 32MB, and often the kernel and other
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* modules are furthur away than this. So, we jump to a table of
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* trampolines attached to the module (the Procedure Linkage Table)
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* whenever that happens.
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*/
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struct ppc_plt_entry {
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/* 16 byte jump instruction sequence (4 instructions) */
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unsigned int jump[4];
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};
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#endif /* __powerpc64__ */
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struct mod_arch_specific {
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#ifdef __powerpc64__
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unsigned int stubs_section; /* Index of stubs section in module */
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unsigned int toc_section; /* What section is the TOC? */
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#ifdef CONFIG_DYNAMIC_FTRACE
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unsigned long toc;
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unsigned long tramp;
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#endif
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#else /* powerpc64 */
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/* Indices of PLT sections within module. */
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unsigned int core_plt_section;
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unsigned int init_plt_section;
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#ifdef CONFIG_DYNAMIC_FTRACE
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unsigned long tramp;
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#endif
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#endif /* powerpc64 */
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/* List of BUG addresses, source line numbers and filenames */
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struct list_head bug_list;
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struct bug_entry *bug_table;
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unsigned int num_bugs;
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};
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/*
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* Select ELF headers.
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* Make empty section for module_frob_arch_sections to expand.
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*/
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#ifdef __powerpc64__
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# ifdef MODULE
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asm(".section .stubs,\"ax\",@nobits; .align 3; .previous");
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# endif
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#else
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# ifdef MODULE
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asm(".section .plt,\"ax\",@nobits; .align 3; .previous");
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asm(".section .init.plt,\"ax\",@nobits; .align 3; .previous");
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# endif /* MODULE */
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#endif
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#ifdef CONFIG_DYNAMIC_FTRACE
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# ifdef MODULE
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asm(".section .ftrace.tramp,\"ax\",@nobits; .align 3; .previous");
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# endif /* MODULE */
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#endif
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struct exception_table_entry;
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void sort_ex_table(struct exception_table_entry *start,
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struct exception_table_entry *finish);
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#if defined(CONFIG_MODVERSIONS) && defined(CONFIG_PPC64)
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#define ARCH_RELOCATES_KCRCTAB
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#define reloc_start PHYSICAL_START
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#endif
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_MODULE_H */
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