From d1898b733619bd46194bd25aa6452d238ff2dc4e Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Wed, 1 Jun 2016 10:42:20 -0700 Subject: [PATCH] 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 Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: Fenghua Yu Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Quentin Casasnovas Cc: Steven Rostedt Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20160601174220.3CDFB90E@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/fpu/internal.h | 5 ++ arch/x86/include/asm/trace/fpu.h | 119 ++++++++++++++++++++++++++++ arch/x86/kernel/fpu/core.c | 18 +++++ arch/x86/kernel/fpu/signal.c | 3 + arch/x86/kvm/x86.c | 6 +- 5 files changed, 148 insertions(+), 3 deletions(-) create mode 100644 arch/x86/include/asm/trace/fpu.h diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index 31ac8e6d9f36..116b58347501 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -18,6 +18,7 @@ #include #include #include +#include /* * High level FPU state handling functions: @@ -524,6 +525,7 @@ static inline void __fpregs_deactivate(struct fpu *fpu) fpu->fpregs_active = 0; this_cpu_write(fpu_fpregs_owner_ctx, NULL); + trace_x86_fpu_regs_deactivated(fpu); } /* Must be paired with a 'clts' (fpregs_activate_hw()) before! */ @@ -533,6 +535,7 @@ static inline void __fpregs_activate(struct fpu *fpu) fpu->fpregs_active = 1; this_cpu_write(fpu_fpregs_owner_ctx, fpu); + trace_x86_fpu_regs_activated(fpu); } /* @@ -604,11 +607,13 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu) /* But leave fpu_fpregs_owner_ctx! */ old_fpu->fpregs_active = 0; + trace_x86_fpu_regs_deactivated(old_fpu); /* Don't change CR0.TS if we just switch! */ if (fpu.preload) { new_fpu->counter++; __fpregs_activate(new_fpu); + trace_x86_fpu_regs_activated(new_fpu); prefetch(&new_fpu->state); } else { __fpregs_deactivate_hw(); diff --git a/arch/x86/include/asm/trace/fpu.h b/arch/x86/include/asm/trace/fpu.h new file mode 100644 index 000000000000..9217ab1f5bf6 --- /dev/null +++ b/arch/x86/include/asm/trace/fpu.h @@ -0,0 +1,119 @@ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM x86_fpu + +#if !defined(_TRACE_FPU_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_FPU_H + +#include + +DECLARE_EVENT_CLASS(x86_fpu, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu), + + TP_STRUCT__entry( + __field(struct fpu *, fpu) + __field(bool, fpregs_active) + __field(bool, fpstate_active) + __field(int, counter) + __field(u64, xfeatures) + __field(u64, xcomp_bv) + ), + + TP_fast_assign( + __entry->fpu = fpu; + __entry->fpregs_active = fpu->fpregs_active; + __entry->fpstate_active = fpu->fpstate_active; + __entry->counter = fpu->counter; + if (boot_cpu_has(X86_FEATURE_OSXSAVE)) { + __entry->xfeatures = fpu->state.xsave.header.xfeatures; + __entry->xcomp_bv = fpu->state.xsave.header.xcomp_bv; + } + ), + TP_printk("x86/fpu: %p fpregs_active: %d fpstate_active: %d counter: %d xfeatures: %llx xcomp_bv: %llx", + __entry->fpu, + __entry->fpregs_active, + __entry->fpstate_active, + __entry->counter, + __entry->xfeatures, + __entry->xcomp_bv + ) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_state, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_before_save, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_after_save, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_before_restore, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_after_restore, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_regs_activated, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_regs_deactivated, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_activate_state, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_deactivate_state, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_init_state, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_dropped, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_copy_src, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_copy_dst, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +DEFINE_EVENT(x86_fpu, x86_fpu_xstate_check_failed, + TP_PROTO(struct fpu *fpu), + TP_ARGS(fpu) +); + +#undef TRACE_INCLUDE_PATH +#define TRACE_INCLUDE_PATH asm/trace/ +#undef TRACE_INCLUDE_FILE +#define TRACE_INCLUDE_FILE fpu +#endif /* _TRACE_FPU_H */ + +/* This part must be outside protection */ +#include diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 97027545a72d..7d564742e499 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -12,6 +12,9 @@ #include +#define CREATE_TRACE_POINTS +#include + /* * Represents the initial FPU state. It's mostly (but not completely) zeroes, * depending on the FPU hardware format: @@ -192,6 +195,7 @@ void fpu__save(struct fpu *fpu) WARN_ON_FPU(fpu != ¤t->thread.fpu); preempt_disable(); + trace_x86_fpu_before_save(fpu); if (fpu->fpregs_active) { if (!copy_fpregs_to_fpstate(fpu)) { if (use_eager_fpu()) @@ -200,6 +204,7 @@ void fpu__save(struct fpu *fpu) fpregs_deactivate(fpu); } } + trace_x86_fpu_after_save(fpu); preempt_enable(); } EXPORT_SYMBOL_GPL(fpu__save); @@ -275,6 +280,9 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu) } preempt_enable(); + trace_x86_fpu_copy_src(src_fpu); + trace_x86_fpu_copy_dst(dst_fpu); + return 0; } @@ -288,7 +296,9 @@ void fpu__activate_curr(struct fpu *fpu) if (!fpu->fpstate_active) { fpstate_init(&fpu->state); + trace_x86_fpu_init_state(fpu); + trace_x86_fpu_activate_state(fpu); /* Safe to do for the current task: */ fpu->fpstate_active = 1; } @@ -314,7 +324,9 @@ void fpu__activate_fpstate_read(struct fpu *fpu) } else { if (!fpu->fpstate_active) { fpstate_init(&fpu->state); + trace_x86_fpu_init_state(fpu); + trace_x86_fpu_activate_state(fpu); /* Safe to do for current and for stopped child tasks: */ fpu->fpstate_active = 1; } @@ -347,7 +359,9 @@ void fpu__activate_fpstate_write(struct fpu *fpu) fpu->last_cpu = -1; } else { fpstate_init(&fpu->state); + trace_x86_fpu_init_state(fpu); + trace_x86_fpu_activate_state(fpu); /* Safe to do for stopped child tasks: */ fpu->fpstate_active = 1; } @@ -432,9 +446,11 @@ void fpu__restore(struct fpu *fpu) /* Avoid __kernel_fpu_begin() right after fpregs_activate() */ kernel_fpu_disable(); + trace_x86_fpu_before_restore(fpu); fpregs_activate(fpu); copy_kernel_to_fpregs(&fpu->state); fpu->counter++; + trace_x86_fpu_after_restore(fpu); kernel_fpu_enable(); } EXPORT_SYMBOL_GPL(fpu__restore); @@ -463,6 +479,8 @@ void fpu__drop(struct fpu *fpu) fpu->fpstate_active = 0; + trace_x86_fpu_dropped(fpu); + preempt_enable(); } diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 31c6a60505e6..c6f2a3cee2c2 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -10,6 +10,7 @@ #include #include +#include static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32; @@ -282,6 +283,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) */ state_size = sizeof(struct fxregs_state); fx_only = 1; + trace_x86_fpu_xstate_check_failed(fpu); } else { state_size = fx_sw_user.xstate_size; xfeatures = fx_sw_user.xfeatures; @@ -311,6 +313,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) if (__copy_from_user(&fpu->state.xsave, buf_fx, state_size) || __copy_from_user(&env, buf, sizeof(env))) { fpstate_init(&fpu->state); + trace_x86_fpu_init_state(fpu); err = -1; } else { sanitize_restored_xstate(tsk, &env, xfeatures, fx_only); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 902d9da12392..1ba3b7d3cae9 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -55,9 +55,6 @@ #include #include -#define CREATE_TRACE_POINTS -#include "trace.h" - #include #include #include @@ -68,6 +65,9 @@ #include #include +#define CREATE_TRACE_POINTS +#include "trace.h" + #define MAX_IO_MSRS 256 #define KVM_MAX_MCE_BANKS 32 #define KVM_MCE_CAP_SUPPORTED (MCG_CTL_P | MCG_SER_P) -- GitLab