cpuid_e{a,b,c,d}x() functions compile to 44 bytes of machine code each.
On x86 allyesconfig build they have 48 callsites.
Deinlining all four of them shrinks kernel by about 1k:
text data bss dec hex filename
82434909 22255384 20627456 125317749 7783275 vmlinux.before
82433898 22255384 20627456 125316738 7782e82 vmlinux
Speed impact: CPUID instruction takes from 50 to 350+ cycles,
call overhead is negligible in comparison.
Signed-off-by: Denys Vlasenko <dvlas...@redhat.com>
CC: Steven Rostedt <rost...@goodmis.org>
CC: Ingo Molnar <mi...@kernel.org>
CC: Borislav Petkov <b...@alien8.de>
CC: "H. Peter Anvin" <h...@zytor.com>
CC: Andy Lutomirski <l...@amacapital.net>
CC: Frederic Weisbecker <fweis...@gmail.com>
CC: Alexei Starovoitov <a...@plumgrid.com>
CC: Will Drewry <w...@chromium.org>
CC: Kees Cook <keesc...@chromium.org>
CC: x...@kernel.org
CC: linux-kernel@vger.kernel.org
---
arch/x86/include/asm/processor.h | 39 ++++--------------------------------
arch/x86/kernel/cpu/common.c | 43 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 47 insertions(+), 35 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index ec1c935..67e1974 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -616,41 +616,10 @@ static inline void cpuid_count(unsigned int op, int count,
/*
* CPUID functions returning a single datum
*/
-static inline unsigned int cpuid_eax(unsigned int op)
-{
- unsigned int eax, ebx, ecx, edx;
-
- cpuid(op, &eax, &ebx, &ecx, &edx);
-
- return eax;
-}
-
-static inline unsigned int cpuid_ebx(unsigned int op)
-{
- unsigned int eax, ebx, ecx, edx;
-
- cpuid(op, &eax, &ebx, &ecx, &edx);
-
- return ebx;
-}
-
-static inline unsigned int cpuid_ecx(unsigned int op)
-{
- unsigned int eax, ebx, ecx, edx;
-
- cpuid(op, &eax, &ebx, &ecx, &edx);
-
- return ecx;
-}
-
-static inline unsigned int cpuid_edx(unsigned int op)
-{
- unsigned int eax, ebx, ecx, edx;
-
- cpuid(op, &eax, &ebx, &ecx, &edx);
-
- return edx;
-}
+unsigned int cpuid_eax(unsigned int op);
+unsigned int cpuid_ebx(unsigned int op);
+unsigned int cpuid_ecx(unsigned int op);
+unsigned int cpuid_edx(unsigned int op);
/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
static inline void rep_nop(void)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 2346c95..1d2e270 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -307,6 +307,49 @@ static __always_inline void setup_smap(struct cpuinfo_x86
*c)
}
/*
+ * CPUID functions returning a single datum
+ */
+unsigned int cpuid_eax(unsigned int op)
+{
+ unsigned int eax, ebx, ecx, edx;
+
+ cpuid(op, &eax, &ebx, &ecx, &edx);
+
+ return eax;
+}
+EXPORT_SYMBOL(cpuid_eax);
+
+unsigned int cpuid_ebx(unsigned int op)
+{
+ unsigned int eax, ebx, ecx, edx;
+
+ cpuid(op, &eax, &ebx, &ecx, &edx);
+
+ return ebx;
+}
+EXPORT_SYMBOL(cpuid_ebx);
+
+unsigned int cpuid_ecx(unsigned int op)
+{
+ unsigned int eax, ebx, ecx, edx;
+
+ cpuid(op, &eax, &ebx, &ecx, &edx);
+
+ return ecx;
+}
+EXPORT_SYMBOL(cpuid_ecx);
+
+unsigned int cpuid_edx(unsigned int op)
+{
+ unsigned int eax, ebx, ecx, edx;
+
+ cpuid(op, &eax, &ebx, &ecx, &edx);
+
+ return edx;
+}
+EXPORT_SYMBOL(cpuid_edx);
+
+/*
* Some CPU features depend on higher CPUID levels, which may not always
* be available due to CPUID level capping or broken virtualization
* software. Add those features to this table to auto-disable them.
--
1.8.1.4
--
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