Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 6 Apr 2022 09:37:03 -0700 | From | Josh Poimboeuf <> | Subject | Re: drivers/gpu/drm/i915/i915.prelink.o: warning: objtool: __intel_wait_for_register_fw.cold()+0xce: relocation to !ENDBR: vlv_allow_gt_wake.cold+0x0 |
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On Wed, Apr 06, 2022 at 09:43:30AM +0200, Peter Zijlstra wrote: > On Tue, Apr 05, 2022 at 10:32:51PM -0700, Josh Poimboeuf wrote: > > More broadly, this issue could theoretically happen in some other places > > throughout the kernel tree, since _THIS_IP_ is fundamentally unreliable > > as currently written. > > > > So we could look at making _THIS_IP_ more predictable. > > > > Inline asm would work better ("lea 0(%rip), %[rip]"), but then you need > > an arch-dependent implementation... > > Well, there's a ton of _THIS_IP_ instances all around, and it would be > unfortunate to have them grow into actual code :/
What do you mean by growing into actual code? It's still just a single instruction, as was the immediate load before.
Though, you pasted this on irc:
#define _THIS_IP_ ({ __label__ __here; __here: asm_volatile_goto ("":::: __here); (unsigned long)&&__here; })
which seems decent to me, though less than ideal because it grows an ENDBR. But I like its arch-independence, so yeah, LGTM.
-- Josh
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