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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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4
arch/x86/lib/retpoline.S
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@@ -71,6 +71,8 @@ SYM_CODE_END(__x86_indirect_thunk_array)
* This function name is magical and is used by -mfunction-return=thunk-extern
* for the compiler to generate JMPs to it.
*/
#ifdef CONFIG_RETHUNK
.section .text.__x86.return_thunk
/*
@@ -135,3 +137,5 @@ SYM_FUNC_END(zen_untrain_ret)
__EXPORT_THUNK(zen_untrain_ret)
EXPORT_SYMBOL(__x86_return_thunk)
#endif /* CONFIG_RETHUNK */