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| author | Peter Zijlstra <peterz@infradead.org> | 2023-05-15 11:28:05 +0200 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-05-31 10:21:21 +0200 |
| commit | df25edbac31ea87b488789d44a362063542b5967 (patch) | |
| tree | b1d07931c90fee18415cda9e054b7a710d2760ef /arch/x86/kernel/alternative.c | |
| parent | d42a2a89121071cc8dd285235253a4c739641635 (diff) | |
| download | linux-df25edbac31ea87b488789d44a362063542b5967.tar.gz linux-df25edbac31ea87b488789d44a362063542b5967.tar.bz2 linux-df25edbac31ea87b488789d44a362063542b5967.zip | |
x86/alternatives: Add longer 64-bit NOPs
By adding support for longer NOPs there are a few more alternatives
that can turn into a single instruction.
Add up to NOP11, the same limit where GNU as .nops also stops
generating longer nops. This is because a number of uarchs have severe
decode penalties for more than 3 prefixes.
[ bp: Sync up with the version in tools/ while at it. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230515093020.661756940@infradead.org
Diffstat (limited to 'arch/x86/kernel/alternative.c')
| -rw-r--r-- | arch/x86/kernel/alternative.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 93aa95afd005..0747d29c8eaf 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -98,6 +98,11 @@ static const unsigned char x86nops[] = BYTES_NOP6, BYTES_NOP7, BYTES_NOP8, +#ifdef CONFIG_64BIT + BYTES_NOP9, + BYTES_NOP10, + BYTES_NOP11, +#endif }; const unsigned char * const x86_nops[ASM_NOP_MAX+1] = @@ -111,6 +116,11 @@ const unsigned char * const x86_nops[ASM_NOP_MAX+1] = x86nops + 1 + 2 + 3 + 4 + 5, x86nops + 1 + 2 + 3 + 4 + 5 + 6, x86nops + 1 + 2 + 3 + 4 + 5 + 6 + 7, +#ifdef CONFIG_64BIT + x86nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8, + x86nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9, + x86nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10, +#endif }; /* |