mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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e769742d35
This reverts commit 5bdcd510c2.
The macro based workarounds for GCC's inlining bugs caused regressions: distcc
and other distro build setups broke, and the fixes are not easy nor will they
solve regressions on already existing installations.
So we are reverting this patch and the 8 followup patches.
What makes this revert easier is that GCC9 will likely include the new 'asm inline'
syntax that makes inlining of assembly blocks a lot more robust.
This is a superior method to any macro based hackeries - and might even be
backported to GCC8, which would make all modern distros get the inlining
fixes as well.
Many thanks to Masahiro Yamada and others for helping sort out these problems.
Reported-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Borislav Petkov <bp@alien8.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: Richard Biener <rguenther@suse.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
106 lines
2.4 KiB
C
106 lines
2.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_JUMP_LABEL_H
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#define _ASM_X86_JUMP_LABEL_H
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#ifndef HAVE_JUMP_LABEL
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/*
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* For better or for worse, if jump labels (the gcc extension) are missing,
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* then the entire static branch patching infrastructure is compiled out.
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* If that happens, the code in here will malfunction. Raise a compiler
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* error instead.
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*
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* In theory, jump labels and the static branch patching infrastructure
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* could be decoupled to fix this.
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*/
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#error asm/jump_label.h included on a non-jump-label kernel
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#endif
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#define JUMP_LABEL_NOP_SIZE 5
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#ifdef CONFIG_X86_64
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# define STATIC_KEY_INIT_NOP P6_NOP5_ATOMIC
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#else
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# define STATIC_KEY_INIT_NOP GENERIC_NOP5_ATOMIC
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#endif
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#include <asm/asm.h>
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#include <asm/nops.h>
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#ifndef __ASSEMBLY__
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#include <linux/stringify.h>
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#include <linux/types.h>
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static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
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{
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asm_volatile_goto("1:"
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".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
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".pushsection __jump_table, \"aw\" \n\t"
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_ASM_ALIGN "\n\t"
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".long 1b - ., %l[l_yes] - . \n\t"
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_ASM_PTR "%c0 + %c1 - .\n\t"
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".popsection \n\t"
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: : "i" (key), "i" (branch) : : l_yes);
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return false;
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l_yes:
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return true;
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}
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static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
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{
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asm_volatile_goto("1:"
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".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t"
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"2:\n\t"
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".pushsection __jump_table, \"aw\" \n\t"
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_ASM_ALIGN "\n\t"
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".long 1b - ., %l[l_yes] - . \n\t"
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_ASM_PTR "%c0 + %c1 - .\n\t"
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".popsection \n\t"
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: : "i" (key), "i" (branch) : : l_yes);
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return false;
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l_yes:
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return true;
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}
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#else /* __ASSEMBLY__ */
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.macro STATIC_JUMP_IF_TRUE target, key, def
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.Lstatic_jump_\@:
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.if \def
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/* Equivalent to "jmp.d32 \target" */
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.byte 0xe9
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.long \target - .Lstatic_jump_after_\@
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.Lstatic_jump_after_\@:
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.else
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.byte STATIC_KEY_INIT_NOP
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.endif
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.pushsection __jump_table, "aw"
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_ASM_ALIGN
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.long .Lstatic_jump_\@ - ., \target - .
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_ASM_PTR \key - .
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.popsection
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.endm
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.macro STATIC_JUMP_IF_FALSE target, key, def
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.Lstatic_jump_\@:
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.if \def
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.byte STATIC_KEY_INIT_NOP
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.else
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/* Equivalent to "jmp.d32 \target" */
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.byte 0xe9
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.long \target - .Lstatic_jump_after_\@
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.Lstatic_jump_after_\@:
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.endif
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.pushsection __jump_table, "aw"
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_ASM_ALIGN
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.long .Lstatic_jump_\@ - ., \target - .
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_ASM_PTR \key + 1 - .
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.popsection
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.endm
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#endif /* __ASSEMBLY__ */
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#endif
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