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SubjectRe: [RFC][PATCH 00/24] x86/pti: Defer CR3 switch to C code
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On 11/9/20 6:44 AM, Alexandre Chartre wrote:
> - map more syscall, interrupt and exception entry code into the user
> page-table (map all noinstr code);

This seems like the thing we'd want to tag explicitly rather than make
it implicit with 'noinstr' code. Worst-case, shouldn't this be:

#define __entry_func noinstr

or something?

I'd also like to see a lot more discussion about what the rules are for
the C code and the compiler. We can't, for instance, do a normal
printk() in this entry functions. Should we stick them in a special
section and have objtool look for suspect patterns or references?

I'm most worried about things like this:

if (something_weird)
pr_warn("this will oops the kernel\n");

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