From 90eec103b96e30401c0b846045bf8a1c7159b6da Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 16 Nov 2015 11:08:45 +0100 Subject: treewide: Remove old email address There were still a number of references to my old Red Hat email address in the kernel source. Remove these while keeping the Red Hat copyright notices intact. Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Signed-off-by: Ingo Molnar --- arch/sparc/kernel/perf_event.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/sparc/kernel/perf_event.c') diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c index b0da5aedb336..3091267c5cc3 100644 --- a/arch/sparc/kernel/perf_event.c +++ b/arch/sparc/kernel/perf_event.c @@ -9,7 +9,7 @@ * Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar * Copyright (C) 2009 Jaswinder Singh Rajput * Copyright (C) 2009 Advanced Micro Devices, Inc., Robert Richter - * Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra + * Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra */ #include -- cgit v1.2.3 From 3f74306ac84cf7f2da2fdc87014fc455f5e67bad Mon Sep 17 00:00:00 2001 From: Rob Gardner Date: Tue, 22 Dec 2015 21:16:06 -0700 Subject: sparc64: Ensure perf can access user stacks When an interrupt (such as a perf counter interrupt) is delivered while executing in user space, the trap entry code puts ASI_AIUS in %asi so that copy_from_user() and copy_to_user() will access the correct memory. But if a perf counter interrupt is delivered while the cpu is already executing in kernel space, then the trap entry code will put ASI_P in %asi, and this will prevent copy_from_user() from reading any useful stack data in either of the perf_callchain_user_X functions, and thus no user callgraph data will be collected for this sample period. An additional problem is that a fault is guaranteed to occur, and though it will be silently covered up, it wastes time and could perturb state. In perf_callchain_user(), we ensure that %asi contains ASI_AIUS because we know for a fact that the subsequent calls to copy_from_user() are intended to read the user's stack. [ Use get_fs()/set_fs() -DaveM ] Signed-off-by: Rob Gardner Signed-off-by: Dave Aldridge Signed-off-by: David S. Miller --- arch/sparc/kernel/perf_event.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch/sparc/kernel/perf_event.c') diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c index 3091267c5cc3..b1144d6acffe 100644 --- a/arch/sparc/kernel/perf_event.c +++ b/arch/sparc/kernel/perf_event.c @@ -1828,11 +1828,16 @@ static void perf_callchain_user_32(struct perf_callchain_entry *entry, void perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) { + mm_segment_t old_fs; + perf_callchain_store(entry, regs->tpc); if (!current->mm) return; + old_fs = get_fs(); + set_fs(USER_DS); + flushw_user(); pagefault_disable(); @@ -1843,4 +1848,6 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) perf_callchain_user_64(entry, regs); pagefault_enable(); + + set_fs(old_fs); } -- cgit v1.2.3 From 833526941f5945cf0b22a595bb8f3525b512f654 Mon Sep 17 00:00:00 2001 From: Rob Gardner Date: Tue, 22 Dec 2015 21:16:07 -0700 Subject: sparc64: Perf should save/restore fault info There have been several reports of random processes being killed with a bus error or segfault during userspace stack walking in perf. One of the root causes of this problem is an asynchronous modification to thread_info fault_address and fault_code, which stems from a perf counter interrupt arriving during kernel processing of a "benign" fault, such as a TSB miss. Since perf_callchain_user() invokes copy_from_user() to read user stacks, a fault is not only possible, but probable. Validity checks on the stack address merely cover up the problem and reduce its frequency. The solution here is to save and restore fault_address and fault_code in perf_callchain_user() so that the benign fault handler is not disturbed by a perf interrupt. Signed-off-by: Rob Gardner Signed-off-by: Dave Aldridge Signed-off-by: David S. Miller --- arch/sparc/kernel/perf_event.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/sparc/kernel/perf_event.c') diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c index b1144d6acffe..6596f66ce112 100644 --- a/arch/sparc/kernel/perf_event.c +++ b/arch/sparc/kernel/perf_event.c @@ -1828,6 +1828,8 @@ static void perf_callchain_user_32(struct perf_callchain_entry *entry, void perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) { + u64 saved_fault_address = current_thread_info()->fault_address; + u8 saved_fault_code = get_thread_fault_code(); mm_segment_t old_fs; perf_callchain_store(entry, regs->tpc); @@ -1850,4 +1852,6 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) pagefault_enable(); set_fs(old_fs); + set_thread_fault_code(saved_fault_code); + current_thread_info()->fault_address = saved_fault_address; } -- cgit v1.2.3