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author | Jeremy Fitzhardinge <jeremy@goop.org> | 2009-01-28 14:35:02 -0800 |
---|---|---|
committer | H. Peter Anvin <hpa@linux.intel.com> | 2009-01-30 14:51:44 -0800 |
commit | 41edafdb78feac1d1f8823846209975fde990633 (patch) | |
tree | 00bb95195332962916be365c6119f17a22770758 /arch/x86/include/asm/paravirt.h | |
parent | 319f3ba52c71630865b10ac3b99dd020440d681d (diff) | |
download | kernel_samsung_tuna-41edafdb78feac1d1f8823846209975fde990633.zip kernel_samsung_tuna-41edafdb78feac1d1f8823846209975fde990633.tar.gz kernel_samsung_tuna-41edafdb78feac1d1f8823846209975fde990633.tar.bz2 |
x86/pvops: add a paravirt_ident functions to allow special patching
Impact: Optimization
Several paravirt ops implementations simply return their arguments,
the most obvious being the make_pte/pte_val class of operations on
native.
On 32-bit, the identity function is literally a no-op, as the calling
convention uses the same registers for the first argument and return.
On 64-bit, it can be implemented with a single "mov".
This patch adds special identity functions for 32 and 64 bit argument,
and machinery to recognize them and replace them with either nops or a
mov as appropriate.
At the moment, the only users for the identity functions are the
pagetable entry conversion functions.
The result is a measureable improvement on pagetable-heavy benchmarks
(2-3%, reducing the pvops overhead from 5 to 2%).
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'arch/x86/include/asm/paravirt.h')
-rw-r--r-- | arch/x86/include/asm/paravirt.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index 1757788..961d10c 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -388,6 +388,8 @@ extern struct pv_lock_ops pv_lock_ops; asm("start_" #ops "_" #name ": " code "; end_" #ops "_" #name ":") unsigned paravirt_patch_nop(void); +unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len); +unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len); unsigned paravirt_patch_ignore(unsigned len); unsigned paravirt_patch_call(void *insnbuf, const void *target, u16 tgt_clobbers, @@ -1371,6 +1373,9 @@ static inline void __set_fixmap(unsigned /* enum fixed_addresses */ idx, } void _paravirt_nop(void); +u32 _paravirt_ident_32(u32); +u64 _paravirt_ident_64(u64); + #define paravirt_nop ((void *)_paravirt_nop) void paravirt_use_bytelocks(void); |