Messages in this thread Patch in this message | | | Date | Tue, 25 Oct 2022 16:59:56 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH 4/5] x86/ftrace: Remove SYSTEM_BOOTING exceptions |
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On Tue, 25 Oct 2022 22:07:00 +0200 Peter Zijlstra <peterz@infradead.org> wrote:
> Now that text_poke is available before ftrace, remove the > SYSTEM_BOOTING exceptions. > > Specifically, this cures a W+X case during boot.
We have W+X all over the place (the entire kernel text). And I don't think we really want this.
This will slow down boots in general, as it will cause all static_branches to use this memory page logic. And I don't think we really want to do that at boot up when we don't need to.
I would change this to:
if (unlikely(system_state == SYSTEM_BOOTING) && core_kernel_text((unsigned long)addr)) {
This way we still do memcpy() on all core kernel text which is still writable. It was the ftrace allocated trampoline that caused issues, not the locations that were being updated.
-- Steve
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > arch/x86/kernel/alternative.c | 10 ---------- > arch/x86/kernel/ftrace.c | 3 +-- > 2 files changed, 1 insertion(+), 12 deletions(-) > > --- a/arch/x86/kernel/alternative.c > +++ b/arch/x86/kernel/alternative.c > @@ -1681,11 +1681,6 @@ void __ref text_poke_queue(void *addr, c > { > struct text_poke_loc *tp; > > - if (unlikely(system_state == SYSTEM_BOOTING)) { > - text_poke_early(addr, opcode, len); > - return; > - } > - > text_poke_flush(addr); > > tp = &tp_vec[tp_vec_nr++]; > @@ -1707,11 +1702,6 @@ void __ref text_poke_bp(void *addr, cons > { > struct text_poke_loc tp; > > - if (unlikely(system_state == SYSTEM_BOOTING)) { > - text_poke_early(addr, opcode, len); > - return; > - } > - > text_poke_loc_init(&tp, addr, opcode, len, emulate); > text_poke_bp_batch(&tp, 1); > } > --- a/arch/x86/kernel/ftrace.c > +++ b/arch/x86/kernel/ftrace.c > @@ -415,8 +415,7 @@ create_trampoline(struct ftrace_ops *ops > > set_vm_flush_reset_perms(trampoline); > > - if (likely(system_state != SYSTEM_BOOTING)) > - set_memory_ro((unsigned long)trampoline, npages); > + set_memory_ro((unsigned long)trampoline, npages); > set_memory_x((unsigned long)trampoline, npages); > return (unsigned long)trampoline; > fail: >
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