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    Subject[PATCH AUTOSEL 5.10 17/19] powerpc/64: Init jump labels before parse_early_param()
    Date
    From: Zhouyi Zhou <zhouzhouyi@gmail.com>

    [ Upstream commit ca829e05d3d4f728810cc5e4b468d9ebc7745eb3 ]

    On 64-bit, calling jump_label_init() in setup_feature_keys() is too
    late because static keys may be used in subroutines of
    parse_early_param() which is again subroutine of early_init_devtree().

    For example booting with "threadirqs":

    static_key_enable_cpuslocked(): static key '0xc000000002953260' used before call to jump_label_init()
    WARNING: CPU: 0 PID: 0 at kernel/jump_label.c:166 static_key_enable_cpuslocked+0xfc/0x120
    ...
    NIP static_key_enable_cpuslocked+0xfc/0x120
    LR static_key_enable_cpuslocked+0xf8/0x120
    Call Trace:
    static_key_enable_cpuslocked+0xf8/0x120 (unreliable)
    static_key_enable+0x30/0x50
    setup_forced_irqthreads+0x28/0x40
    do_early_param+0xa0/0x108
    parse_args+0x290/0x4e0
    parse_early_options+0x48/0x5c
    parse_early_param+0x58/0x84
    early_init_devtree+0xd4/0x518
    early_setup+0xb4/0x214

    So call jump_label_init() just before parse_early_param() in
    early_init_devtree().

    Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
    Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
    [mpe: Add call trace to change log and minor wording edits.]
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
    Link: https://lore.kernel.org/r/20220726015747.11754-1-zhouzhouyi@gmail.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/powerpc/kernel/prom.c | 7 +++++++
    1 file changed, 7 insertions(+)

    diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
    index 7a14a094be8a..1dfb4c213fea 100644
    --- a/arch/powerpc/kernel/prom.c
    +++ b/arch/powerpc/kernel/prom.c
    @@ -750,6 +750,13 @@ void __init early_init_devtree(void *params)
    of_scan_flat_dt(early_init_dt_scan_root, NULL);
    of_scan_flat_dt(early_init_dt_scan_memory_ppc, NULL);

    + /*
    + * As generic code authors expect to be able to use static keys
    + * in early_param() handlers, we initialize the static keys just
    + * before parsing early params (it's fine to call jump_label_init()
    + * more than once).
    + */
    + jump_label_init();
    parse_early_param();

    /* make sure we've parsed cmdline for mem= before this */
    --
    2.35.1
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