[Xen-devel] [PATCH 08/12] x86: create specific X86_VSYSCALL config variable

[Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>]

vsyscalls are only implemented on 64-bit at present, though there's no
fundimental reason why they couldn't be implemented for 32-bit.  Create
a new CONFIG_X86_VSYSCALL to control compilation of vsyscall-related
code and definitions to make it clearer where they are.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
---
 arch/x86/Kconfig              |    6 +++++-
 arch/x86/include/asm/fixmap.h |    7 +++++--
 arch/x86/kernel/Makefile      |    3 ++-
 arch/x86/kernel/hpet.c        |    4 ++--
 arch/x86/kernel/tsc.c         |    4 ++--
 5 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 13ffa5d..7950d54 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -136,7 +136,7 @@ config GENERIC_CALIBRATE_DELAY
 
 config GENERIC_TIME_VSYSCALL
        bool
-       default X86_64
+       default X86_VSYSCALL
 
 config ARCH_HAS_CPU_RELAX
        def_bool y
@@ -222,6 +222,10 @@ config X86_32_LAZY_GS
        def_bool y
        depends on X86_32 && !CC_STACKPROTECTOR
 
+config X86_VSYSCALL
+       def_bool y
+       depends on X86_64
+
 config KTIME_SCALAR
        def_bool X86_32
 source "init/Kconfig"
diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index 7b2d71d..3b63b57 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -74,12 +74,15 @@ enum fixed_addresses {
 #ifdef CONFIG_X86_32
        FIX_HOLE,
        FIX_VDSO,
-#else
+#endif
+
+#ifdef CONFIG_X86_VSYSCALL
        VSYSCALL_LAST_PAGE,
        VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE
                            + ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
        VSYSCALL_HPET,
-#endif
+#endif /* CONFIG_X86_VSYSCALL */
+
        FIX_DBGP_BASE,
        FIX_EARLYCON_MEM_BASE,
 #ifdef CONFIG_X86_LOCAL_APIC
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 430d5b2..1c9ec2f 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -37,7 +37,8 @@ obj-$(CONFIG_X86_VISWS)       += visws_quirks.o
 obj-$(CONFIG_X86_32)   += probe_roms_32.o
 obj-$(CONFIG_X86_32)   += sys_i386_32.o i386_ksyms_32.o
 obj-$(CONFIG_X86_64)   += sys_x86_64.o x8664_ksyms_64.o
-obj-$(CONFIG_X86_64)   += syscall_64.o vsyscall_64.o
+obj-$(CONFIG_X86_64)   += syscall_64.o
+obj-$(CONFIG_X86_VSYSCALL)     += vsyscall_64.o
 obj-y                  += bootflag.o e820.o
 obj-y                  += pci-dma.o quirks.o i8237.o topology.o kdebugfs.o
 obj-y                  += alternative.o i8253.o pci-nommu.o
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index dedc2bd..2cac930 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -744,7 +744,7 @@ static cycle_t read_hpet(struct clocksource *cs)
        return (cycle_t)hpet_readl(HPET_COUNTER);
 }
 
-#ifdef CONFIG_X86_64
+#ifdef CONFIG_X86_VSYSCALL
 static cycle_t __vsyscall_fn vread_hpet(void)
 {
        return readl((const void __iomem *)fix_to_virt(VSYSCALL_HPET) + 0xf0);
@@ -759,7 +759,7 @@ static struct clocksource clocksource_hpet = {
        .shift          = HPET_SHIFT,
        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
        .resume         = hpet_resume_counter,
-#ifdef CONFIG_X86_64
+#ifdef CONFIG_X86_VSYSCALL
        .vread          = vread_hpet,
 #endif
 };
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 71f4368..fe7174f 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -725,7 +725,7 @@ static cycle_t read_tsc(struct clocksource *cs)
                ret : clocksource_tsc.cycle_last;
 }
 
-#ifdef CONFIG_X86_64
+#ifdef CONFIG_X86_VSYSCALL
 static cycle_t __vsyscall_fn vread_tsc(void)
 {
        cycle_t ret;
@@ -752,7 +752,7 @@ static struct clocksource clocksource_tsc = {
        .shift                  = 22,
        .flags                  = CLOCK_SOURCE_IS_CONTINUOUS |
                                  CLOCK_SOURCE_MUST_VERIFY,
-#ifdef CONFIG_X86_64
+#ifdef CONFIG_X86_VSYSCALL
        .vread                  = vread_tsc,
 #endif
 };
-- 
1.6.2.5


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