x86/vdso: Get pvclock data from the vvar VMA instead of the fixmap
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>
diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c
index c325ba1..5dd363d 100644
--- a/arch/x86/entry/vdso/vclock_gettime.c
+++ b/arch/x86/entry/vdso/vclock_gettime.c
@@ -36,6 +36,11 @@
}
#endif
+#ifdef CONFIG_PARAVIRT_CLOCK
+extern u8 pvclock_page
+ __attribute__((visibility("hidden")));
+#endif
+
#ifndef BUILD_VDSO32
#include <linux/kernel.h>
@@ -62,23 +67,14 @@
#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 de2c921..4158acc 100644
--- a/arch/x86/entry/vdso/vdso-layout.lds.S
+++ b/arch/x86/entry/vdso/vdso-layout.lds.S
@@ -25,7 +25,7 @@
* 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 @@
#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 785d992..491020b 100644
--- a/arch/x86/entry/vdso/vdso2c.c
+++ b/arch/x86/entry/vdso/vdso2c.c
@@ -73,6 +73,7 @@
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 @@
const int special_pages[] = {
sym_vvar_page,
sym_hpet_page,
+ sym_pvclock_page,
};
struct vdso_sym {
@@ -91,6 +93,7 @@
[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 64df471..aa82819 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -100,6 +100,7 @@
.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 @@
}
#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;