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    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
    \
     
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