lkml.org 
[lkml]   [2018]   [Feb]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Date
Subject[PATCH 3.16 131/136] x86/vdso: Get pvclock data from the vvar VMA instead of the fixmap
3.16.54-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Lutomirski <luto@kernel.org>

commit dac16fba6fc590fa7239676b35ed75dae4c4cd2b upstream.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/9d37826fdc7e2d2809efe31d5345f97186859284.1449702533.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.16: adjust filenames]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/x86/vdso/vclock_gettime.c | 20 ++++++++------------
arch/x86/vdso/vdso-layout.lds.S | 3 ++-
arch/x86/vdso/vdso2c.c | 3 +++
arch/x86/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(-)

--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/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(s

#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;
--- a/arch/x86/vdso/vdso-layout.lds.S
+++ b/arch/x86/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;

--- a/arch/x86/vdso/vdso2c.c
+++ b/arch/x86/vdso/vdso2c.c
@@ -23,6 +23,7 @@ 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,
};
@@ -30,6 +31,7 @@ enum {
const int special_pages[] = {
sym_vvar_page,
sym_hpet_page,
+ sym_pvclock_page,
};

struct vdso_sym {
@@ -41,6 +43,7 @@ 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
},
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -113,6 +113,7 @@ static int map_vdso(const struct vdso_im
.name = "[vvar]",
.pages = no_pages,
};
+ struct pvclock_vsyscall_time_info *pvti;

if (calculate_addr) {
addr = vdso_addr(current->mm->start_stack,
@@ -182,6 +183,18 @@ static int map_vdso(const struct vdso_im
}
#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;
--- 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);
--- 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;
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -44,6 +44,11 @@ early_param("no-kvmclock", parse_no_kvmc
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
\
 
 \ /
  Last update: 2018-02-11 05:56    [W:0.286 / U:0.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site