x86/fpu: Add tracepoints to dump FPU state at key points
I've been carrying this patch around for a bit and it's helped me solve at least a couple FPU-related bugs. In addition to using it for debugging, I also drug it out because using AVX (and AVX2/AVX-512) can have serious power consequences for a modern core. It's very important to be able to figure out who is using it. It's also insanely useful to go out and see who is using a given feature, like MPX or Memory Protection Keys. If you, for instance, want to find all processes using protection keys, you can do: echo 'xfeatures & 0x200' > filter Since 0x200 is the protection keys feature bit. Note that this touches the KVM code. KVM did a CREATE_TRACE_POINTS and then included a bunch of random headers. If anyone one of those included other tracepoints, it would have defined the *OTHER* tracepoints. That's bogus, so move it to the right place. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave@sr71.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20160601174220.3CDFB90E@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Dave Hansen
Ingo Molnar
Родитель
c8ae067f26
Коммит
d1898b7336
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@ -18,6 +18,7 @@
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#include <asm/fpu/api.h>
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#include <asm/fpu/xstate.h>
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#include <asm/cpufeature.h>
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#include <asm/trace/fpu.h>
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/*
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* High level FPU state handling functions:
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@ -524,6 +525,7 @@ static inline void __fpregs_deactivate(struct fpu *fpu)
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fpu->fpregs_active = 0;
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this_cpu_write(fpu_fpregs_owner_ctx, NULL);
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trace_x86_fpu_regs_deactivated(fpu);
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}
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/* Must be paired with a 'clts' (fpregs_activate_hw()) before! */
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@ -533,6 +535,7 @@ static inline void __fpregs_activate(struct fpu *fpu)
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fpu->fpregs_active = 1;
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this_cpu_write(fpu_fpregs_owner_ctx, fpu);
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trace_x86_fpu_regs_activated(fpu);
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}
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/*
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@ -604,11 +607,13 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu)
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/* But leave fpu_fpregs_owner_ctx! */
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old_fpu->fpregs_active = 0;
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trace_x86_fpu_regs_deactivated(old_fpu);
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/* Don't change CR0.TS if we just switch! */
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if (fpu.preload) {
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new_fpu->counter++;
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__fpregs_activate(new_fpu);
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trace_x86_fpu_regs_activated(new_fpu);
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prefetch(&new_fpu->state);
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} else {
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__fpregs_deactivate_hw();
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@ -0,0 +1,119 @@
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#undef TRACE_SYSTEM
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#define TRACE_SYSTEM x86_fpu
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#if !defined(_TRACE_FPU_H) || defined(TRACE_HEADER_MULTI_READ)
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#define _TRACE_FPU_H
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#include <linux/tracepoint.h>
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DECLARE_EVENT_CLASS(x86_fpu,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu),
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TP_STRUCT__entry(
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__field(struct fpu *, fpu)
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__field(bool, fpregs_active)
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__field(bool, fpstate_active)
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__field(int, counter)
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__field(u64, xfeatures)
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__field(u64, xcomp_bv)
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),
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TP_fast_assign(
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__entry->fpu = fpu;
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__entry->fpregs_active = fpu->fpregs_active;
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__entry->fpstate_active = fpu->fpstate_active;
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__entry->counter = fpu->counter;
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if (boot_cpu_has(X86_FEATURE_OSXSAVE)) {
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__entry->xfeatures = fpu->state.xsave.header.xfeatures;
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__entry->xcomp_bv = fpu->state.xsave.header.xcomp_bv;
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}
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),
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TP_printk("x86/fpu: %p fpregs_active: %d fpstate_active: %d counter: %d xfeatures: %llx xcomp_bv: %llx",
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__entry->fpu,
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__entry->fpregs_active,
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__entry->fpstate_active,
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__entry->counter,
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__entry->xfeatures,
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__entry->xcomp_bv
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)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_state,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_before_save,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_after_save,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_before_restore,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_after_restore,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_regs_activated,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_regs_deactivated,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_activate_state,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_deactivate_state,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_init_state,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_dropped,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_copy_src,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_copy_dst,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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DEFINE_EVENT(x86_fpu, x86_fpu_xstate_check_failed,
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TP_PROTO(struct fpu *fpu),
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TP_ARGS(fpu)
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);
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#undef TRACE_INCLUDE_PATH
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#define TRACE_INCLUDE_PATH asm/trace/
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#undef TRACE_INCLUDE_FILE
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#define TRACE_INCLUDE_FILE fpu
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#endif /* _TRACE_FPU_H */
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/* This part must be outside protection */
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#include <trace/define_trace.h>
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@ -12,6 +12,9 @@
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#include <linux/hardirq.h>
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#define CREATE_TRACE_POINTS
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#include <asm/trace/fpu.h>
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/*
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* Represents the initial FPU state. It's mostly (but not completely) zeroes,
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* depending on the FPU hardware format:
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@ -192,6 +195,7 @@ void fpu__save(struct fpu *fpu)
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WARN_ON_FPU(fpu != ¤t->thread.fpu);
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preempt_disable();
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trace_x86_fpu_before_save(fpu);
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if (fpu->fpregs_active) {
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if (!copy_fpregs_to_fpstate(fpu)) {
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if (use_eager_fpu())
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@ -200,6 +204,7 @@ void fpu__save(struct fpu *fpu)
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fpregs_deactivate(fpu);
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}
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}
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trace_x86_fpu_after_save(fpu);
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preempt_enable();
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}
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EXPORT_SYMBOL_GPL(fpu__save);
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@ -275,6 +280,9 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
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}
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preempt_enable();
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trace_x86_fpu_copy_src(src_fpu);
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trace_x86_fpu_copy_dst(dst_fpu);
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return 0;
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}
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@ -288,7 +296,9 @@ void fpu__activate_curr(struct fpu *fpu)
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if (!fpu->fpstate_active) {
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fpstate_init(&fpu->state);
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trace_x86_fpu_init_state(fpu);
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trace_x86_fpu_activate_state(fpu);
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/* Safe to do for the current task: */
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fpu->fpstate_active = 1;
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}
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@ -314,7 +324,9 @@ void fpu__activate_fpstate_read(struct fpu *fpu)
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} else {
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if (!fpu->fpstate_active) {
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fpstate_init(&fpu->state);
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trace_x86_fpu_init_state(fpu);
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trace_x86_fpu_activate_state(fpu);
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/* Safe to do for current and for stopped child tasks: */
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fpu->fpstate_active = 1;
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}
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@ -347,7 +359,9 @@ void fpu__activate_fpstate_write(struct fpu *fpu)
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fpu->last_cpu = -1;
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} else {
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fpstate_init(&fpu->state);
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trace_x86_fpu_init_state(fpu);
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trace_x86_fpu_activate_state(fpu);
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/* Safe to do for stopped child tasks: */
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fpu->fpstate_active = 1;
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}
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@ -432,9 +446,11 @@ void fpu__restore(struct fpu *fpu)
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/* Avoid __kernel_fpu_begin() right after fpregs_activate() */
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kernel_fpu_disable();
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trace_x86_fpu_before_restore(fpu);
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fpregs_activate(fpu);
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copy_kernel_to_fpregs(&fpu->state);
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fpu->counter++;
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trace_x86_fpu_after_restore(fpu);
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kernel_fpu_enable();
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}
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EXPORT_SYMBOL_GPL(fpu__restore);
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@ -463,6 +479,8 @@ void fpu__drop(struct fpu *fpu)
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fpu->fpstate_active = 0;
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trace_x86_fpu_dropped(fpu);
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preempt_enable();
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}
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@ -10,6 +10,7 @@
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#include <asm/fpu/regset.h>
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#include <asm/sigframe.h>
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#include <asm/trace/fpu.h>
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static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
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@ -282,6 +283,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
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*/
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state_size = sizeof(struct fxregs_state);
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fx_only = 1;
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trace_x86_fpu_xstate_check_failed(fpu);
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} else {
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state_size = fx_sw_user.xstate_size;
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xfeatures = fx_sw_user.xfeatures;
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@ -311,6 +313,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
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if (__copy_from_user(&fpu->state.xsave, buf_fx, state_size) ||
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__copy_from_user(&env, buf, sizeof(env))) {
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fpstate_init(&fpu->state);
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trace_x86_fpu_init_state(fpu);
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err = -1;
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} else {
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sanitize_restored_xstate(tsk, &env, xfeatures, fx_only);
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@ -55,9 +55,6 @@
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#include <linux/irqbypass.h>
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#include <trace/events/kvm.h>
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#define CREATE_TRACE_POINTS
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#include "trace.h"
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#include <asm/debugreg.h>
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#include <asm/msr.h>
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#include <asm/desc.h>
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@ -68,6 +65,9 @@
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#include <asm/div64.h>
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#include <asm/irq_remapping.h>
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#define CREATE_TRACE_POINTS
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#include "trace.h"
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#define MAX_IO_MSRS 256
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#define KVM_MAX_MCE_BANKS 32
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#define KVM_MCE_CAP_SUPPORTED (MCG_CTL_P | MCG_SER_P)
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