On Tue, Nov 10, 2015 at 12:48:42PM +0100, Borislav Petkov wrote:
> From: Borislav Petkov <[email protected]>
>
> Those are stupid and code should use static_cpu_has_safe() anyway. Kill
> the least used and unused ones.
>
> Signed-off-by: Borislav Petkov <[email protected]>
> Cc: Herbert Xu <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Matt Mackall <[email protected]>
> Cc: Chris Mason <[email protected]>
> Cc: Josef Bacik <[email protected]>
> Cc: David Sterba <[email protected]>
> ---
> arch/x86/crypto/chacha20_glue.c | 2 +-
> arch/x86/crypto/crc32c-intel_glue.c | 3 ++-
> arch/x86/include/asm/cmpxchg_32.h | 2 +-
> arch/x86/include/asm/cpufeature.h | 32
> +++--------------------------
> arch/x86/include/asm/smp.h | 2 +-
> arch/x86/kernel/cpu/amd.c | 2 +-
> arch/x86/kernel/cpu/intel.c | 3 ++-
> arch/x86/kernel/cpu/mtrr/generic.c | 2 +-
> arch/x86/kernel/cpu/mtrr/main.c | 2 +-
> arch/x86/kernel/cpu/perf_event_amd.c | 4 ++--
> arch/x86/kernel/cpu/perf_event_amd_uncore.c | 8 ++++----
> arch/x86/kernel/fpu/init.c | 4 ++--
> arch/x86/kernel/hw_breakpoint.c | 3 ++-
> arch/x86/kernel/vm86_32.c | 4 +++-
> arch/x86/mm/setup_nx.c | 4 ++--
> drivers/char/hw_random/via-rng.c | 5 +++--
> drivers/crypto/padlock-aes.c | 2 +-
> drivers/crypto/padlock-sha.c | 3 ++-
> fs/btrfs/disk-io.c | 2 +-
> 19 files changed, 35 insertions(+), 54 deletions(-)
Ok, 0day says this patch makes tiny not so tiny:
i386-tinyconfig vmlinux size:
+-------+------+-------+-----+--------------------------------------------------------------------------------------+
| TOTAL | TEXT | DATA | BSS |
|
+-------+------+-------+-----+--------------------------------------------------------------------------------------+
| +4646 | +64 | +4096 | 0 | ab9976b5af96 x86/cpufeature: Remove unused and
seldomly used cpu_has_xx macros |
| -32 | -32 | 0 | 0 | 13e835020a02 x86/cpufeature: Cleanup
get_cpu_cap() |
| +32 | +32 | 0 | 0 | 3615f94f0486 x86/cpufeature: Move some of the
scattered feature bits to x86_capabili |
| +136 | +32 | 0 | 0 | 506d983184f4 Merge branch 'tip-fpu-xsave' into
rc2+ |
| +4782 | +96 | +4096 | 0 | ALL COMMITS
|
+-------+------+-------+-----+--------------------------------------------------------------------------------------+
Btw, thanks 0day!
The problem comes from static_cpu_has_safe() adding the alternatives and
fallback machinery. For example, before the patch, we had this at the
cpu_has_* testing sites:
movl boot_cpu_data+20, %eax # MEM[(const long unsigned int
*)&boot_cpu_data + 20B], D.19113
testl $2097152, %eax #, D.19113
je .L166 #,
and now we get this:
#APP
# 449 "arch/x86/kernel/cpu/intel.c" 1
# 0 "" 2
# 511 "./arch/x86/include/asm/cpufeature.h" 1
1: jmp .L166 #
2:
.skip -(((5f-4f) - (2b-1b)) > 0) * ((5f-4f) - (2b-1b)),0x90
3:
.section .altinstructions,"a"
.long 1b - .
.long 4f - .
.word 117 #
.byte 3b - 1b
.byte 5f - 4f
.byte 3b - 2b
.previous
.section .altinstr_replacement,"ax"
4: jmp .L167 #
5:
.previous
.section .altinstructions,"a"
.long 1b - .
.long 0
.word 21 #
.byte 3b - 1b
.byte 0
.byte 0
.previous
# 0 "" 2
#NO_APP
jmp .L168 #
.L166:
movl $21, %eax #,
call __static_cpu_has_safe #
testb %al, %al # D.19126
je .L167 #,
.L168:
#APP
# 453 "arch/x86/kernel/cpu/intel.c" 1
# 0 "" 2
#NO_APP
That gets spread among .altinstructions, .altinstr_replacement, .text
etc sections. .data grows too probably because of the NOP padding :-\
text data bss dec hex filename
before: 644896 127436 1189384 1961716 1deef4 vmlinux
after: 645446 131532 1189384 1966362 1e011a vmlinux
[Nr] Name Type Addr Off Size ES Flg Lk
Inf Al
before: [12] .altinstructions PROGBITS c10bdf48 0bef48 000680 00 A 0
0 1
after: [12] .altinstructions PROGBITS c10bff48 0c0f48 0007d2 00 A 0
0 1
before: [13] .altinstr_replace PROGBITS c10be5c8 0bf5c8 00016c 00 AX 0
0 1
after: [13] .altinstr_replace PROGBITS c10c071a 0c171a 0001ad 00 AX 0
0 1
before: [ 7] .data PROGBITS c1092000 093000 0132a0 00 WA 0
0 4096
after: [ 7] .data PROGBITS c1093000 094000 0142a0 00 WA 0
0 4096
So I'm wondering if we should make a config option which converts
static_cpu_has* macros to boot_cpu_has()? That should slim down
the kernel even more but it won't benefit from the speedup of the
static_cpu_has* stuff.
Josh, thoughts?
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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