RE: [PATCH v2 2/6] x86-64: Convert stack protector to normal percpu variable

[David Laight]

From: Brian Gerst
> Sent: 30 November 2021 20:56
> 
> Older versions of GCC fixed the location of the stack protector canary
> at %gs:40.  This constraint forced the percpu section to be linked at
> virtual address 0 so that the canary could be the first data object in
> the percpu section.  Supporting the zero-based percpu section requires
> additional code to handle relocations for RIP-relative references to
> percpu data, extra complexity to kallsyms, and workarounds for linker
> bugs due to the use of absolute symbols.
> 
> Since version 8.1, GCC has options to configure the location of the
> canary value.  This allows the canary to be turned into a normal
> percpu variable and removes the constraint that the percpu section
> be zero-based.

I didn't think the minimum gcc version has been raised as far as 8.1?

	David

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