From: Dave Hansen <dave@sr71.net> To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, x86@kernel.org, Dave Hansen <dave@sr71.net>, dave.hansen@linux.intel.com Subject: [PATCH 02/34] x86, fpu: add placeholder for Processor Trace XSAVE state Date: Thu, 03 Dec 2015 17:14:28 -0800 [thread overview] Message-ID: <20151204011428.B65C1D48@viggo.jf.intel.com> (raw) In-Reply-To: <20151204011424.8A36E365@viggo.jf.intel.com> From: Dave Hansen <dave.hansen@linux.intel.com> x86 Maintainers, I submitted this independently, but it must be applied before adding subsequent patches. Please drop this if it has already been applied. --- From: Dave Hansen <dave.hansen@linux.intel.com> There is an XSAVE state component for Intel Processor Trace. But, we do not use it and do not expect to ever use it. We add a placeholder in the code for it so it is not a mystery and also so we do not need an explicit enum initialization for Protection Keys in a moment. Why will we never use it? According to Andi Kleen: The XSAVE support assumes that there is a single buffer for each thread. But perf generally doesn't work this way, it usually has only a single perf event per CPU per user, and when tracing multiple threads on that CPU it inherits perf event buffers between different threads. So XSAVE per thread cannot handle this inheritance case directly. Using multiple XSAVE areas (another one per perf event) would defeat some of the state caching that the CPUs do. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> --- b/arch/x86/include/asm/fpu/types.h | 1 + b/arch/x86/kernel/fpu/xstate.c | 10 ++++++++-- 2 files changed, 9 insertions(+), 2 deletions(-) diff -puN arch/x86/include/asm/fpu/types.h~pt-xstate-bit arch/x86/include/asm/fpu/types.h --- a/arch/x86/include/asm/fpu/types.h~pt-xstate-bit 2015-12-03 16:21:19.003370936 -0800 +++ b/arch/x86/include/asm/fpu/types.h 2015-12-03 16:21:19.008371163 -0800 @@ -108,6 +108,7 @@ enum xfeature { XFEATURE_OPMASK, XFEATURE_ZMM_Hi256, XFEATURE_Hi16_ZMM, + XFEATURE_PT_UNIMPLEMENTED_SO_FAR, XFEATURE_MAX, }; diff -puN arch/x86/kernel/fpu/xstate.c~pt-xstate-bit arch/x86/kernel/fpu/xstate.c --- a/arch/x86/kernel/fpu/xstate.c~pt-xstate-bit 2015-12-03 16:21:19.004370981 -0800 +++ b/arch/x86/kernel/fpu/xstate.c 2015-12-03 16:21:19.008371163 -0800 @@ -13,6 +13,11 @@ #include <asm/tlbflush.h> +/* + * Although we spell it out in here, the Processor Trace + * xfeature is completely unused. We use other mechanisms + * to save/restore PT state in Linux. + */ static const char *xfeature_names[] = { "x87 floating point registers" , @@ -23,7 +28,7 @@ static const char *xfeature_names[] = "AVX-512 opmask" , "AVX-512 Hi256" , "AVX-512 ZMM_Hi256" , - "unknown xstate feature" , + "Processor Trace (unused)" , }; /* @@ -469,7 +474,8 @@ static void check_xstate_against_struct( * numbers. */ if ((nr < XFEATURE_YMM) || - (nr >= XFEATURE_MAX)) { + (nr >= XFEATURE_MAX) || + (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR)) { WARN_ONCE(1, "no structure for xstate: %d\n", nr); XSTATE_WARN_ON(1); } _
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave@sr71.net> To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, x86@kernel.org, Dave Hansen <dave@sr71.net>, dave.hansen@linux.intel.com Subject: [PATCH 02/34] x86, fpu: add placeholder for Processor Trace XSAVE state Date: Thu, 03 Dec 2015 17:14:28 -0800 [thread overview] Message-ID: <20151204011428.B65C1D48@viggo.jf.intel.com> (raw) In-Reply-To: <20151204011424.8A36E365@viggo.jf.intel.com> From: Dave Hansen <dave.hansen@linux.intel.com> x86 Maintainers, I submitted this independently, but it must be applied before adding subsequent patches. Please drop this if it has already been applied. --- From: Dave Hansen <dave.hansen@linux.intel.com> There is an XSAVE state component for Intel Processor Trace. But, we do not use it and do not expect to ever use it. We add a placeholder in the code for it so it is not a mystery and also so we do not need an explicit enum initialization for Protection Keys in a moment. Why will we never use it? According to Andi Kleen: The XSAVE support assumes that there is a single buffer for each thread. But perf generally doesn't work this way, it usually has only a single perf event per CPU per user, and when tracing multiple threads on that CPU it inherits perf event buffers between different threads. So XSAVE per thread cannot handle this inheritance case directly. Using multiple XSAVE areas (another one per perf event) would defeat some of the state caching that the CPUs do. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> --- b/arch/x86/include/asm/fpu/types.h | 1 + b/arch/x86/kernel/fpu/xstate.c | 10 ++++++++-- 2 files changed, 9 insertions(+), 2 deletions(-) diff -puN arch/x86/include/asm/fpu/types.h~pt-xstate-bit arch/x86/include/asm/fpu/types.h --- a/arch/x86/include/asm/fpu/types.h~pt-xstate-bit 2015-12-03 16:21:19.003370936 -0800 +++ b/arch/x86/include/asm/fpu/types.h 2015-12-03 16:21:19.008371163 -0800 @@ -108,6 +108,7 @@ enum xfeature { XFEATURE_OPMASK, XFEATURE_ZMM_Hi256, XFEATURE_Hi16_ZMM, + XFEATURE_PT_UNIMPLEMENTED_SO_FAR, XFEATURE_MAX, }; diff -puN arch/x86/kernel/fpu/xstate.c~pt-xstate-bit arch/x86/kernel/fpu/xstate.c --- a/arch/x86/kernel/fpu/xstate.c~pt-xstate-bit 2015-12-03 16:21:19.004370981 -0800 +++ b/arch/x86/kernel/fpu/xstate.c 2015-12-03 16:21:19.008371163 -0800 @@ -13,6 +13,11 @@ #include <asm/tlbflush.h> +/* + * Although we spell it out in here, the Processor Trace + * xfeature is completely unused. We use other mechanisms + * to save/restore PT state in Linux. + */ static const char *xfeature_names[] = { "x87 floating point registers" , @@ -23,7 +28,7 @@ static const char *xfeature_names[] = "AVX-512 opmask" , "AVX-512 Hi256" , "AVX-512 ZMM_Hi256" , - "unknown xstate feature" , + "Processor Trace (unused)" , }; /* @@ -469,7 +474,8 @@ static void check_xstate_against_struct( * numbers. */ if ((nr < XFEATURE_YMM) || - (nr >= XFEATURE_MAX)) { + (nr >= XFEATURE_MAX) || + (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR)) { WARN_ONCE(1, "no structure for xstate: %d\n", nr); XSTATE_WARN_ON(1); } _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2015-12-04 1:23 UTC|newest] Thread overview: 145+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-12-04 1:14 [PATCH 00/34] x86: Memory Protection Keys (v5) Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 01/34] mm, gup: introduce concept of "foreign" get_user_pages() Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` Dave Hansen [this message] 2015-12-04 1:14 ` [PATCH 02/34] x86, fpu: add placeholder for Processor Trace XSAVE state Dave Hansen 2015-12-04 1:14 ` [PATCH 03/34] x86, pkeys: Add Kconfig option Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 04/34] x86, pkeys: cpuid bit definition Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 05/34] x86, pkeys: define new CR4 bit Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 06/34] x86, pkeys: add PKRU xsave fields and data structure(s) Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 07/34] x86, pkeys: PTE bits for storing protection key Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 08/34] x86, pkeys: new page fault error code bit: PF_PK Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 09/34] x86, pkeys: store protection in high VMA flags Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-08 14:17 ` Thomas Gleixner 2015-12-08 14:17 ` Thomas Gleixner 2015-12-04 1:14 ` [PATCH 10/34] x86, pkeys: arch-specific protection bits Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-08 15:15 ` [PATCH 10/34] x86, pkeys: arch-specific protection bitsy Thomas Gleixner 2015-12-08 15:15 ` Thomas Gleixner 2015-12-08 16:34 ` Dave Hansen 2015-12-08 16:34 ` Dave Hansen 2015-12-08 17:24 ` Thomas Gleixner 2015-12-08 17:24 ` Thomas Gleixner 2015-12-08 18:06 ` Dave Hansen 2015-12-08 18:29 ` Thomas Gleixner 2015-12-08 18:29 ` Thomas Gleixner 2015-12-08 18:35 ` Thomas Gleixner 2015-12-08 18:35 ` Thomas Gleixner 2015-12-04 1:14 ` [PATCH 11/34] x86, pkeys: pass VMA down in to fault signal generation code Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 12/34] signals, pkeys: notify userspace about protection key faults Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 13/34] x86, pkeys: fill in pkey field in siginfo Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 14/34] x86, pkeys: add functions to fetch PKRU Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-08 15:18 ` Thomas Gleixner 2015-12-08 15:18 ` Thomas Gleixner 2015-12-04 1:14 ` [PATCH 15/34] mm: factor out VMA fault permission checking Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-08 17:26 ` Thomas Gleixner 2015-12-08 17:26 ` Thomas Gleixner 2015-12-04 1:14 ` [PATCH 16/34] x86, mm: simplify get_user_pages() PTE bit handling Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-08 18:01 ` Thomas Gleixner 2015-12-08 18:01 ` Thomas Gleixner 2015-12-08 18:30 ` Dave Hansen 2015-12-08 18:30 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 17/34] x86, pkeys: check VMAs and PTEs for protection keys Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-08 18:11 ` Thomas Gleixner 2015-12-08 18:11 ` Thomas Gleixner 2015-12-04 1:14 ` [PATCH 18/34] mm: add gup flag to indicate "foreign" mm access Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 19/34] x86, pkeys: optimize fault handling in access_error() Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-08 18:14 ` Thomas Gleixner 2015-12-08 18:14 ` Thomas Gleixner 2015-12-04 1:14 ` [PATCH 20/34] x86, pkeys: differentiate instruction fetches Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-08 18:17 ` Thomas Gleixner 2015-12-08 18:17 ` Thomas Gleixner 2015-12-04 1:14 ` [PATCH 21/34] x86, pkeys: dump PKRU with other kernel registers Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-08 18:19 ` Thomas Gleixner 2015-12-08 18:19 ` Thomas Gleixner 2015-12-04 1:14 ` [PATCH 22/34] x86, pkeys: dump PTE pkey in /proc/pid/smaps Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-08 18:20 ` Thomas Gleixner 2015-12-08 18:20 ` Thomas Gleixner 2015-12-04 1:14 ` [PATCH 23/34] x86, pkeys: add Kconfig prompt to existing config option Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-08 18:21 ` Thomas Gleixner 2015-12-08 18:21 ` Thomas Gleixner 2015-12-04 1:14 ` [PATCH 24/34] mm, multi-arch: pass a protection key in to calc_vm_flag_bits() Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-04 1:14 ` [PATCH 25/34] x86, pkeys: add arch_validate_pkey() Dave Hansen 2015-12-04 1:14 ` Dave Hansen 2015-12-08 18:39 ` Thomas Gleixner 2015-12-08 18:39 ` Thomas Gleixner 2015-12-04 1:15 ` [PATCH 26/34] mm: implement new mprotect_key() system call Dave Hansen 2015-12-04 1:15 ` Dave Hansen 2015-12-05 6:50 ` Michael Kerrisk (man-pages) 2015-12-05 6:50 ` Michael Kerrisk (man-pages) 2015-12-05 6:50 ` Michael Kerrisk (man-pages) 2015-12-07 16:44 ` Dave Hansen 2015-12-07 16:44 ` Dave Hansen 2015-12-09 11:08 ` Michael Kerrisk (man-pages) 2015-12-09 11:08 ` Michael Kerrisk (man-pages) 2015-12-09 15:48 ` Dave Hansen 2015-12-09 15:48 ` Dave Hansen 2015-12-09 16:45 ` Michael Kerrisk (man-pages) 2015-12-09 16:45 ` Michael Kerrisk (man-pages) 2015-12-09 16:45 ` Michael Kerrisk (man-pages) 2015-12-09 17:05 ` Dave Hansen 2015-12-09 17:05 ` Dave Hansen 2015-12-09 17:05 ` Dave Hansen 2015-12-11 20:13 ` Michael Kerrisk (man-pages) 2015-12-11 20:13 ` Michael Kerrisk (man-pages) 2015-12-04 1:15 ` [PATCH 27/34] x86, pkeys: make mprotect_key() mask off additional vm_flags Dave Hansen 2015-12-04 1:15 ` Dave Hansen 2015-12-08 18:41 ` Thomas Gleixner 2015-12-08 18:41 ` Thomas Gleixner 2015-12-04 1:15 ` [PATCH 28/34] x86: wire up mprotect_key() system call Dave Hansen 2015-12-04 1:15 ` Dave Hansen 2015-12-08 18:44 ` Thomas Gleixner 2015-12-08 18:44 ` Thomas Gleixner 2015-12-08 18:44 ` Thomas Gleixner 2015-12-08 19:06 ` Dave Hansen 2015-12-08 19:06 ` Dave Hansen 2015-12-08 20:38 ` Thomas Gleixner 2015-12-08 20:38 ` Thomas Gleixner 2015-12-08 20:38 ` Thomas Gleixner 2015-12-04 1:15 ` [PATCH 29/34] x86: separate out LDT init from context init Dave Hansen 2015-12-04 1:15 ` Dave Hansen 2015-12-08 18:45 ` Thomas Gleixner 2015-12-08 18:45 ` Thomas Gleixner 2015-12-04 1:15 ` [PATCH 30/34] x86, fpu: allow setting of XSAVE state Dave Hansen 2015-12-04 1:15 ` Dave Hansen 2015-12-08 18:48 ` Thomas Gleixner 2015-12-08 18:48 ` Thomas Gleixner 2015-12-04 1:15 ` [PATCH 31/34] x86, pkeys: allocation/free syscalls Dave Hansen 2015-12-04 1:15 ` Dave Hansen 2015-12-04 1:15 ` [PATCH 32/34] x86, pkeys: add pkey set/get syscalls Dave Hansen 2015-12-04 1:15 ` Dave Hansen 2015-12-04 1:15 ` [PATCH 33/34] x86, pkeys: actually enable Memory Protection Keys in CPU Dave Hansen 2015-12-04 1:15 ` Dave Hansen 2015-12-04 1:15 ` [PATCH 34/34] x86, pkeys: Documentation Dave Hansen 2015-12-04 1:15 ` Dave Hansen 2015-12-04 23:31 ` [PATCH 00/34] x86: Memory Protection Keys (v5) Andy Lutomirski 2015-12-04 23:31 ` Andy Lutomirski 2015-12-04 23:38 ` Dave Hansen 2015-12-04 23:38 ` Dave Hansen 2015-12-04 23:38 ` Dave Hansen 2015-12-11 20:16 ` Andy Lutomirski 2015-12-11 20:16 ` Andy Lutomirski 2015-12-11 20:16 ` Andy Lutomirski
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