Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [patch V4 part 2 10/18] x86/entry/64: Check IF in __preempt_enable_notrace() thunk | Date | Tue, 12 May 2020 10:14:04 +0200 |
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Steven Rostedt <rostedt@goodmis.org> writes: > On Tue, 05 May 2020 15:41:22 +0200 > Thomas Gleixner <tglx@linutronix.de> 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.
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