Messages in this thread | | | Date | Sat, 8 Jan 2022 07:38:16 +0700 | Subject | Re: [PATCH v1 3/3] Documentation: x86-64: Document registers on entry and exit | From | Ammar Faizi <> |
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On 1/8/22 7:02 AM, Andy Lutomirski wrote: > On 1/7/22 15:52, Ammar Faizi wrote: >> There was a controversial discussion about the wording in the System >> V ABI document regarding what registers the kernel is allowed to >> clobber when the userspace executes syscall. >> >> The resolution of the discussion was reviewing the clobber list in >> the glibc source. For a historical reason in the glibc source, the >> kernel must restore all registers before returning to the userspace >> (except for rax, rcx and r11). >> [...] >> diff --git a/Documentation/x86/entry_64.rst b/Documentation/x86/entry_64.rst >> index e433e08f7018..3f2007e2a938 100644 >> --- a/Documentation/x86/entry_64.rst >> +++ b/Documentation/x86/entry_64.rst >> @@ -108,3 +108,50 @@ We try to only use IST entries and the paranoid entry code for vectors >> that absolutely need the more expensive check for the GS base - and we >> generate all 'normal' entry points with the regular (faster) paranoid=0 >> variant. >> + >> + >> +Registers on entry: >> +------------------- > > This is SYSCALL64 registers on entry, not general registers on entry. > Also, this has little to do with the entry logic, so it probably > doesn't belong in this file.
Ah right, I should be more specific saying it's for syscall64 entry as there are 6 entries mentioned in this document.
Should syscall64 entry topic be documented? If not I will drop it, otherwise suggest me a place for it.
I think we can document it here, but it needs to be more specific saying it's for syscall64 entry.
Jonathan?
-- Ammar Faizi [unhandled content-type:application/pgp-signature] | |