Le 20/02/2024 à 21:32, Maxwell Bland a écrit :

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Present non-uniform use of __vmalloc_node and __vmalloc_node_range makes
enforcing appropriate code and data seperation untenable on certain
microarchitectures, as VMALLOC_START and VMALLOC_END are monolithic
while the use of the vmalloc interface is non-monolithic: in particular,
appropriate randomness in ASLR makes it such that code regions must fall
in some region between VMALLOC_START and VMALLOC_end, but this
necessitates that code pages are intermingled with data pages, meaning
code-specific protections, such as arm64's PXNTable, cannot be
performantly runtime enforced.

The solution to this problem allows architectures to override the
vmalloc wrapper functions by enforcing that the rest of the kernel does
not reimplement __vmalloc_node by using __vmalloc_node_range with the
same parameters as __vmalloc_node or provides a __weak tag to those
functions using __vmalloc_node_range with parameters repeating those of
__vmalloc_node.

Two benefits of this approach are (1) greater flexibility to each
architecture for handling of virtual memory while not compromising the
kernel's vmalloc logic and (2) more uniform use of the __vmalloc_node
interface, reserving the more specialized __vmalloc_node_range for more
specialized cases, such as kasan's shadow memory.

I'm not sure I understand the message. What I understand is that you 
allow architectures to override vmalloc_node().

In the code you add __weak for that. But you also add the flags to the 
parameters and I can't understand why when reading the above description.

Christophe