Messages in this thread | | | Date | Mon, 23 Jan 2023 22:16:01 -0800 | Subject | Re: [RFC PATCH v2 2/2] selftests/x86: sysret_rip: Add more syscall tests with respect to `%rcx` and `%r11` | From | "H. Peter Anvin" <> |
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On 1/23/23 18:27, Ammar Faizi wrote: > From: Ammar Faizi <ammarfaizi2@gnuweeb.org> > > Test that: > > - "syscall" in a FRED system doesn't clobber %rcx and %r11. > - "syscall" in a non-FRED system sets %rcx=%rip and %r11=%rflags. > > Test them out with a trivial system call like __NR_getppid and friends > which are extremely likely to return with SYSRET on an IDT system; check > that it returns a nonnegative value and then save the result. >
"Nonnegative" here should be "valid"; it is an implementation detail that the error value is -1.
However, you are not checking that you don't get a mix of REGS_SAVED and REGS_SYSRET, which is a major part of the point.
-hpa
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