Steven Rostedt <[email protected]> writes: > On Tue, 05 May 2020 15:41:22 +0200 > Thomas Gleixner <[email protected]> wrote: > >> The preempt_enable_notrace() ASM thunk is called from tracing, entry code >> RCU and other places which are already in or going to be in the noinstr >> section which protects sensitve code from being instrumented. >> >> Calls out of these sections happen with interrupts disabled, which is >> handled in C code, but the push regs, call, pop regs sequence can be >> completely avoided in this case. >> >> This is also a preparatory step for annotating the call from the thunk to >> preempt_enable_notrace() safe from a noinstr section. >> > > BTW, after applying this patch, I get the following error: > > /work/git/linux-test.git/arch/x86/entry/thunk_64.S: Assembler messages: > /work/git/linux-test.git/arch/x86/entry/thunk_64.S:67: Error: invalid > operands (*UND* and *UND* sections) for `+' > /work/git/linux-test.git/arch/x86/entry/thunk_64.S:67: Error: invalid > operands (*UND* and *ABS* sections) for `/' > make[3]: *** [/work/git/linux-test.git/scripts/Makefile.build:349: > arch/x86/entry/thunk_64.o] Error 1 > make[3]: *** Waiting for unfinished jobs....
Yes I know, but I'm going to drop that patch completely.
