lkml.org 
[lkml]   [2022]   [Mar]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[tip: x86/core] x86/livepatch: Validate __fentry__ location
    The following commit has been merged into the x86/core branch of tip:

    Commit-ID: a557abfd1a16072e4d25bdf226e3b761e6f10741
    Gitweb: https://git.kernel.org/tip/a557abfd1a16072e4d25bdf226e3b761e6f10741
    Author: Peter Zijlstra <peterz@infradead.org>
    AuthorDate: Tue, 08 Mar 2022 16:30:30 +01:00
    Committer: Peter Zijlstra <peterz@infradead.org>
    CommitterDate: Tue, 08 Mar 2022 23:53:31 +01:00

    x86/livepatch: Validate __fentry__ location

    Currently livepatch assumes __fentry__ lives at func+0, which is most
    likely untrue with IBT on. Instead make it use ftrace_location() by
    default which both validates and finds the actual ip if there is any
    in the same symbol.

    Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
    Link: https://lore.kernel.org/r/20220308154318.285971256@infradead.org
    ---
    arch/powerpc/include/asm/livepatch.h | 10 ----------
    kernel/livepatch/patch.c | 19 ++-----------------
    2 files changed, 2 insertions(+), 27 deletions(-)

    diff --git a/arch/powerpc/include/asm/livepatch.h b/arch/powerpc/include/asm/livepatch.h
    index 4fe018c..7b9dcd5 100644
    --- a/arch/powerpc/include/asm/livepatch.h
    +++ b/arch/powerpc/include/asm/livepatch.h
    @@ -19,16 +19,6 @@ static inline void klp_arch_set_pc(struct ftrace_regs *fregs, unsigned long ip)
    regs_set_return_ip(regs, ip);
    }

    -#define klp_get_ftrace_location klp_get_ftrace_location
    -static inline unsigned long klp_get_ftrace_location(unsigned long faddr)
    -{
    - /*
    - * Live patch works only with -mprofile-kernel on PPC. In this case,
    - * the ftrace location is always within the first 16 bytes.
    - */
    - return ftrace_location_range(faddr, faddr + 16);
    -}
    -
    static inline void klp_init_thread_info(struct task_struct *p)
    {
    /* + 1 to account for STACK_END_MAGIC */
    diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
    index fe316c0..c172bf9 100644
    --- a/kernel/livepatch/patch.c
    +++ b/kernel/livepatch/patch.c
    @@ -124,19 +124,6 @@ unlock:
    ftrace_test_recursion_unlock(bit);
    }

    -/*
    - * Convert a function address into the appropriate ftrace location.
    - *
    - * Usually this is just the address of the function, but on some architectures
    - * it's more complicated so allow them to provide a custom behaviour.
    - */
    -#ifndef klp_get_ftrace_location
    -static unsigned long klp_get_ftrace_location(unsigned long faddr)
    -{
    - return faddr;
    -}
    -#endif
    -
    static void klp_unpatch_func(struct klp_func *func)
    {
    struct klp_ops *ops;
    @@ -153,8 +140,7 @@ static void klp_unpatch_func(struct klp_func *func)
    if (list_is_singular(&ops->func_stack)) {
    unsigned long ftrace_loc;

    - ftrace_loc =
    - klp_get_ftrace_location((unsigned long)func->old_func);
    + ftrace_loc = ftrace_location((unsigned long)func->old_func);
    if (WARN_ON(!ftrace_loc))
    return;

    @@ -186,8 +172,7 @@ static int klp_patch_func(struct klp_func *func)
    if (!ops) {
    unsigned long ftrace_loc;

    - ftrace_loc =
    - klp_get_ftrace_location((unsigned long)func->old_func);
    + ftrace_loc = ftrace_location((unsigned long)func->old_func);
    if (!ftrace_loc) {
    pr_err("failed to find location for function '%s'\n",
    func->old_name);
    \
     
     \ /
      Last update: 2022-03-09 08:57    [W:4.033 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site