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    SubjectRe: [tip:perf/urgent] uprobes: Fix uprobes on MIPS, allow for a cache flush after ixol breakpoint creation
    On 12/19, tip-bot for Marcin Nowakowski wrote:
    >
    > uprobes: Fix uprobes on MIPS, allow for a cache flush after ixol breakpoint creation
    >
    > Commit:
    >
    > 72e6ae285a1d ('ARM: 8043/1: uprobes need icache flush after xol write'
    >
    > ... has introduced an arch-specific method to ensure all caches are
    > flushed appropriately after an instruction is written to an XOL page.

    when this page is already mmaped,

    > However, when the XOL area is created and the out-of-line breakpoint
    > instruction is copied, caches are not flushed at all and stale data may
    > be found in icache.

    but in this case the page is not mmaped yet, the probed application will
    take a page fault if it tries to execute this insn,

    > Replace a simple copy_to_page() with arch_uprobe_copy_ixol() to allow
    > the arch to ensure all caches are updated accordingly.
    >
    > This change fixes uprobes on MIPS InterAptiv (tested on Creator Ci40).

    OK, I know nothing about MIPS, but could you help me understand this change?

    See above. If we really need flush_icache_range() here then perhaps we should
    modify install_special_mapping() and/or __do_fault/special_mapping_fault paths
    instead?

    Oleg.

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