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    SubjectRe: [PATCH 3/5] uprobes: introduce uprobe_xol_slots[NR_CPUS]
    On 11/28, Oleg Nesterov wrote:
    >
    > This patch adds uprobe_xol_slots[UPROBES_XOL_SLOT_BYTES][NR_CPUS] array.

    Typo, it should be uprobe_xol_slots[NR_CPUS][UPROBES_XOL_SLOT_BYTES].


    -------------------------------------------------------------------------
    [PATCH 3/5] uprobes: introduce uprobe_xol_slots[NR_CPUS]

    This patch adds uprobe_xol_slots[UPROBES_XOL_SLOT_BYTES][NR_CPUS] array.
    Each CPU has its own slot for xol (used in the next patch).

    We "export" this data to the user-space via set_fixmap(PAGE_KERNEL_VSYSCALL).

    Signed-off-by: Oleg Nesterov <oleg@redhat.com>
    ---
    arch/x86/include/asm/fixmap.h | 9 +++++++++
    arch/x86/kernel/uprobes.c | 10 ++++++++++
    include/linux/uprobes.h | 1 +
    kernel/uprobes.c | 4 ++++
    4 files changed, 24 insertions(+), 0 deletions(-)

    diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
    index 460c74e..a902e19 100644
    --- a/arch/x86/include/asm/fixmap.h
    +++ b/arch/x86/include/asm/fixmap.h
    @@ -81,6 +81,15 @@ enum fixed_addresses {
    VVAR_PAGE,
    VSYSCALL_HPET,
    #endif
    +
    +#ifdef CONFIG_UPROBES
    + #define UPROBES_XOL_SLOT_BYTES 128
    +
    + UPROBE_XOL_LAST_PAGE,
    + UPROBE_XOL_FIRST_PAGE = UPROBE_XOL_LAST_PAGE
    + + NR_CPUS * UPROBES_XOL_SLOT_BYTES / PAGE_SIZE,
    +#endif
    +
    FIX_DBGP_BASE,
    FIX_EARLYCON_MEM_BASE,
    #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
    diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
    index 4140137..ebb280c 100644
    --- a/arch/x86/kernel/uprobes.c
    +++ b/arch/x86/kernel/uprobes.c
    @@ -664,3 +664,13 @@ bool can_skip_xol(struct pt_regs *regs, struct uprobe *u)
    u->flags &= ~UPROBES_SKIP_SSTEP;
    return false;
    }
    +
    +void __init map_uprobe_xol_slots(void *pages)
    +{
    + int idx = UPROBE_XOL_FIRST_PAGE;
    +
    + do {
    + __set_fixmap(idx, __pa(pages), PAGE_KERNEL_VSYSCALL);
    + pages += PAGE_SIZE;
    + } while (idx-- != UPROBE_XOL_LAST_PAGE);
    +}
    diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
    index d590d66..bb59a66 100644
    --- a/include/linux/uprobes.h
    +++ b/include/linux/uprobes.h
    @@ -142,6 +142,7 @@ extern bool uprobe_deny_signal(void);
    extern bool __weak can_skip_xol(struct pt_regs *regs, struct uprobe *u);
    extern void __weak set_xol_ip(struct pt_regs *regs);
    extern void uprobe_switch_to(struct task_struct *);
    +extern void map_uprobe_xol_slots(void *);
    #else /* CONFIG_UPROBES is not defined */
    static inline int register_uprobe(struct inode *inode, loff_t offset,
    struct uprobe_consumer *consumer)
    diff --git a/kernel/uprobes.c b/kernel/uprobes.c
    index 9c509dc..20007da 100644
    --- a/kernel/uprobes.c
    +++ b/kernel/uprobes.c
    @@ -1342,6 +1342,9 @@ bool __weak can_skip_xol(struct pt_regs *regs, struct uprobe *u)
    return false;
    }

    +static unsigned char
    +uprobe_xol_slots[NR_CPUS][UPROBES_XOL_SLOT_BYTES] __page_aligned_bss;
    +
    void __weak set_xol_ip(struct pt_regs *regs)
    {
    set_instruction_pointer(regs, current->utask->xol_vaddr);
    @@ -1490,6 +1493,7 @@ static int __init init_uprobes(void)
    mutex_init(&uprobes_mmap_mutex[i]);
    }
    init_bulkref(&uprobes_srcu);
    + map_uprobe_xol_slots(uprobe_xol_slots);
    return register_die_notifier(&uprobe_exception_nb);
    }

    --
    1.5.5.1



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