Re: [PATCH] x86/paravirt: use %rip-relative addressing in hook calls

From
Juergen Gross via Virtualization <hidden>
Date
2021-10-05 07:43:26
Reply to
Jan Beulich via Virtualization, 2021-09-30
On 30.09.21 14:40, Jan Beulich via Virtualization wrote:
While using a plain (constant) address works, its use needlessly invokes
a SIB addressing mode, making every call site one byte larger than
necessary. Instead of using an "i" constraint with address-of operator
and a 'c' operand modifier, simply use an ordinary "m" constraint, which
the 64-bit compiler will translate to %rip-relative addressing. This way
we also tell the compiler the truth about operand usage - the memory
location gets actually read, after all.

32-bit code generation is unaffected by the change.

Signed-off-by: Jan Beulich <redacted>
Reviewed-by: Juergen Gross <jgross@suse.com>


Juergen
Thread (6 messages) 6 messages, 2 authors, last reply 2022-01-10
Keyboard shortcuts
hback out one level
jnext message in thread / next series-diff position
kprevious message in thread / previous series-diff position
ldrill in
Escclose help / fold thread tree
?toggle this help