lkml.org 
[lkml]   [2022]   [Apr]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.17 291/343] arm64: patch_text: Fixup last cpu should be master
    Date
    From: Guo Ren <guoren@linux.alibaba.com>

    commit 31a099dbd91e69fcab55eef4be15ed7a8c984918 upstream.

    These patch_text implementations are using stop_machine_cpuslocked
    infrastructure with atomic cpu_count. The original idea: When the
    master CPU patch_text, the others should wait for it. But current
    implementation is using the first CPU as master, which couldn't
    guarantee the remaining CPUs are waiting. This patch changes the
    last CPU as the master to solve the potential risk.

    Fixes: ae16480785de ("arm64: introduce interfaces to hotpatch kernel and module code")
    Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
    Signed-off-by: Guo Ren <guoren@kernel.org>
    Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
    Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
    Cc: <stable@vger.kernel.org>
    Link: https://lore.kernel.org/r/20220407073323.743224-2-guoren@kernel.org
    Signed-off-by: Will Deacon <will@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/arm64/kernel/patching.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    --- a/arch/arm64/kernel/patching.c
    +++ b/arch/arm64/kernel/patching.c
    @@ -117,8 +117,8 @@ static int __kprobes aarch64_insn_patch_
    int i, ret = 0;
    struct aarch64_insn_patch *pp = arg;

    - /* The first CPU becomes master */
    - if (atomic_inc_return(&pp->cpu_count) == 1) {
    + /* The last CPU becomes master */
    + if (atomic_inc_return(&pp->cpu_count) == num_online_cpus()) {
    for (i = 0; ret == 0 && i < pp->insn_cnt; i++)
    ret = aarch64_insn_patch_text_nosync(pp->text_addrs[i],
    pp->new_insns[i]);

    \
     
     \ /
      Last update: 2022-04-12 11:13    [W:4.096 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site