On Thu, Jun 29, 2017 at 10:05 PM, Andy Lutomirski <luto@xxxxxxxxxx> wrote: > Hmm. There's another option that might be considerably nicer, though: > put the IRQ stack at a known (at link time) position *in percpu > space*. (Presumably it already is -- I haven't checked.) Then we do: > > .macro ENTER_IRQ_STACK old_rsp > DEBUG_ENTRY_ASSERT_IRQS_OFF > movq %rsp, \old_rsp > incl PER_CPU_VAR(irq_count) > > /* > * Right now, if we just incremented irq_count to zero, we've > * claimed the IRQ stack but we haven't switched to it yet. > * Anything that can interrupt us here without using IST > * must be *extremely* careful to limit its stack usage. > */ > jnz .Lpush_old_rsp_\@ > movq \old_rsp, PER_CPU_VAR(top_word_in_irq_stack) > movq PER_CPU_VAR(irq_stack_ptr), %rsp > .Lpush_old_rsp_\@: > pushq \old_rsp > .endm > How about the two commits here (well, soon to be there once gitweb catches up): https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git/commit/?h=x86/entry_irq_stack&id=0f56a55bb133cd53ccb78ca51378086296618322 If you like them, want to add them to your series? -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
