[PATCH 3/5] x86/vdso: Get pvclock data from the vvar VMA instead of the fixmap
From: Andy Lutomirski
Date: Wed Dec 09 2015 - 18:13:58 EST
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
---
arch/x86/entry/vdso/vclock_gettime.c | 20 ++++++++------------
arch/x86/entry/vdso/vdso-layout.lds.S | 3 ++-
arch/x86/entry/vdso/vdso2c.c | 3 +++
arch/x86/entry/vdso/vma.c | 13 +++++++++++++
arch/x86/include/asm/pvclock.h | 9 +++++++++
arch/x86/include/asm/vdso.h | 1 +
arch/x86/kernel/kvmclock.c | 5 +++++
7 files changed, 41 insertions(+), 13 deletions(-)
diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index c325ba1bdddf..5dd363d54348 100644
--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/vdso/vclock_gettime.c
@@ -36,6 +36,11 @@ static notrace cycle_t vread_hpet(void)
}
#endif
+#ifdef CONFIG_PARAVIRT_CLOCK
+extern u8 pvclock_page
+ __attribute__((visibility("hidden")));
+#endif
+
#ifndef BUILD_VDSO32
#include <linux/kernel.h>
@@ -62,23 +67,14 @@ notrace static long vdso_fallback_gtod(struct timeval *tv, struct timezone *tz)
#ifdef CONFIG_PARAVIRT_CLOCK
-static notrace const struct pvclock_vsyscall_time_info *get_pvti(int cpu)
+static notrace const struct pvclock_vsyscall_time_info *get_pvti0(void)
{
- const struct pvclock_vsyscall_time_info *pvti_base;
- int idx = cpu / (PAGE_SIZE/PVTI_SIZE);
- int offset = cpu % (PAGE_SIZE/PVTI_SIZE);
-
- BUG_ON(PVCLOCK_FIXMAP_BEGIN + idx > PVCLOCK_FIXMAP_END);
-
- pvti_base = (struct pvclock_vsyscall_time_info *)
- __fix_to_virt(PVCLOCK_FIXMAP_BEGIN+idx);
-
- return &pvti_base[offset];
+ return (const struct pvclock_vsyscall_time_info *)&pvclock_page;
}
static notrace cycle_t vread_pvclock(int *mode)
{
- const struct pvclock_vcpu_time_info *pvti = &get_pvti(0)->pvti;
+ const struct pvclock_vcpu_time_info *pvti = &get_pvti0()->pvti;
cycle_t ret;
u64 tsc, pvti_tsc;
u64 last, delta, pvti_system_time;
diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S
index de2c921025f5..4158acc17df0 100644
--- a/arch/x86/entry/vdso/vdso-layout.lds.S
+++ b/arch/x86/entry/vdso/vdso-layout.lds.S
@@ -25,7 +25,7 @@ SECTIONS
* segment.
*/
- vvar_start = . - 2 * PAGE_SIZE;
+ vvar_start = . - 3 * PAGE_SIZE;
vvar_page = vvar_start;
/* Place all vvars at the offsets in asm/vvar.h. */
@@ -36,6 +36,7 @@ SECTIONS
#undef EMIT_VVAR
hpet_page = vvar_start + PAGE_SIZE;
+ pvclock_page = vvar_start + 2 * PAGE_SIZE;
. = SIZEOF_HEADERS;
diff --git a/arch/x86/entry/vdso/vdso2c.c b/arch/x86/entry/vdso/vdso2c.c
index 785d9922b106..491020b2826d 100644
--- a/arch/x86/entry/vdso/vdso2c.c
+++ b/arch/x86/entry/vdso/vdso2c.c
@@ -73,6 +73,7 @@ enum {
sym_vvar_start,
sym_vvar_page,
sym_hpet_page,
+ sym_pvclock_page,
sym_VDSO_FAKE_SECTION_TABLE_START,
sym_VDSO_FAKE_SECTION_TABLE_END,
};
@@ -80,6 +81,7 @@ enum {
const int special_pages[] = {
sym_vvar_page,
sym_hpet_page,
+ sym_pvclock_page,
};
struct vdso_sym {
@@ -91,6 +93,7 @@ struct vdso_sym required_syms[] = {
[sym_vvar_start] = {"vvar_start", true},
[sym_vvar_page] = {"vvar_page", true},
[sym_hpet_page] = {"hpet_page", true},
+ [sym_pvclock_page] = {"pvclock_page", true},
[sym_VDSO_FAKE_SECTION_TABLE_START] = {
"VDSO_FAKE_SECTION_TABLE_START", false
},
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 64df47148160..aa828191c654 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -100,6 +100,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
.name = "[vvar]",
.pages = no_pages,
};
+ struct pvclock_vsyscall_time_info *pvti;
if (calculate_addr) {
addr = vdso_addr(current->mm->start_stack,
@@ -169,6 +170,18 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
}
#endif
+ pvti = pvclock_pvti_cpu0_va();
+ if (pvti && image->sym_pvclock_page) {
+ ret = remap_pfn_range(vma,
+ text_start + image->sym_pvclock_page,
+ __pa(pvti) >> PAGE_SHIFT,
+ PAGE_SIZE,
+ PAGE_READONLY);
+
+ if (ret)
+ goto up_fail;
+ }
+
up_fail:
if (ret)
current->mm->context.vdso = NULL;
diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
index 7a6bed5c08bc..3864398c7cb2 100644
--- a/arch/x86/include/asm/pvclock.h
+++ b/arch/x86/include/asm/pvclock.h
@@ -4,6 +4,15 @@
#include <linux/clocksource.h>
#include <asm/pvclock-abi.h>
+#ifdef CONFIG_PARAVIRT_CLOCK
+extern struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void);
+#else
+static inline struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
+{
+ return NULL;
+}
+#endif
+
/* some helper functions for xen and kvm pv clock sources */
cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h
index 756de9190aec..deabaf9759b6 100644
--- a/arch/x86/include/asm/vdso.h
+++ b/arch/x86/include/asm/vdso.h
@@ -22,6 +22,7 @@ struct vdso_image {
long sym_vvar_page;
long sym_hpet_page;
+ long sym_pvclock_page;
long sym_VDSO32_NOTE_MASK;
long sym___kernel_sigreturn;
long sym___kernel_rt_sigreturn;
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index 2bd81e302427..ec1b06dc82d2 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -45,6 +45,11 @@ early_param("no-kvmclock", parse_no_kvmclock);
static struct pvclock_vsyscall_time_info *hv_clock;
static struct pvclock_wall_clock wall_clock;
+struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
+{
+ return hv_clock;
+}
+
/*
* The wallclock is the time of day when we booted. Since then, some time may
* have elapsed since the hypervisor wrote the data. So we try to account for
--
2.5.0
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