• Victor Kamensky's avatar
    ARM: 8043/1: uprobes need icache flush after xol write · 72e6ae28
    Victor Kamensky authored
    After instruction write into xol area, on ARM V7
    architecture code need to flush dcache and icache to sync
    them up for given set of addresses. Having just
    'flush_dcache_page(page)' call is not enough - it is
    possible to have stale instruction sitting in icache
    for given xol area slot address.
    
    Introduce arch_uprobe_ixol_copy weak function
    that by default calls uprobes copy_to_page function and
    than flush_dcache_page function and on ARM define new one
    that handles xol slot copy in ARM specific way
    
    flush_uprobe_xol_access function shares/reuses implementation
    with/of flush_ptrace_access function and takes care of writing
    instruction to user land address space on given variety of
    different cache types on ARM CPUs. Because
    flush_uprobe_xol_access does not have vma around
    flush_ptrace_access was split into two parts. First that
    retrieves set of condition from vma and common that receives
    those conditions as flags.
    
    Note ARM cache flush function need kernel address
    through which instruction write happened, so instead
    of using uprobes copy_to_page function changed
    code to explicitly map page and do memcpy.
    
    Note arch_uprobe_copy_ixol function, in similar way as
    copy_to_user_page function, has preempt_disable/preempt_enable.
    Signed-off-by: default avatarVictor Kamensky <victor.kamensky@linaro.org>
    Acked-by: default avatarOleg Nesterov <oleg@redhat.com>
    Reviewed-by: default avatarDavid A. Long <dave.long@linaro.org>
    Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
    72e6ae28
uprobes.c 5.13 KB