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x86/retbleed: Add fine grained Kconfig knobs

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commit f43b9876e857c739d407bc56df288b0ebe1a9164 upstream.

Do fine-grained Kconfig for all the various retbleed parts.

NOTE: if your compiler doesn't support return thunks this will
silently 'upgrade' your mitigation to IBPB, you might not like this.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
[cascardo: there is no CONFIG_OBJTOOL]
[cascardo: objtool calling and option parsing has changed]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
[bwh: Backported to 5.10:
 - In scripts/Makefile.build, add the objtool option with an ifdef
   block, same as for other options
 - Adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Zijlstra
2022-06-27 22:21:17 +00:00
committed by Greg Kroah-Hartman
parent f7851ed697
commit b24fdd0f1c
19 changed files with 172 additions and 69 deletions
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5
arch/x86/kernel/alternative.c
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@@ -662,6 +662,7 @@ void __init_or_module noinline apply_retpolines(s32 *start, s32 *end)
}
}
#ifdef CONFIG_RETHUNK
/*
* Rewrite the compiler generated return thunk tail-calls.
*
@@ -723,6 +724,10 @@ void __init_or_module noinline apply_returns(s32 *start, s32 *end)
}
}
}
#else
void __init_or_module noinline apply_returns(s32 *start, s32 *end) { }
#endif /* CONFIG_RETHUNK */
#else /* !RETPOLINES || !CONFIG_STACK_VALIDATION */
void __init_or_module noinline apply_retpolines(s32 *start, s32 *end) { }