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9a7c348ba6
Storing this value will help prevent unwinders from getting out of sync with the function graph tracer ret_stack. Now instead of needing a stateful iterator, they can compare the return address pointer to find the right ret_stack entry. Note that an array of 50 ftrace_ret_stack structs is allocated for every task. So when an arch implements this, it will add either 200 or 400 bytes of memory usage per task (depending on whether it's a 32-bit or 64-bit platform). Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Byungchul Park <byungchul.park@lge.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nilay Vaish <nilayvaish@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/a95cfcc39e8f26b89a430c56926af0bb217bc0a1.1471607358.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
89 lines
2.2 KiB
C
89 lines
2.2 KiB
C
/*
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* Code for tracing calls in Linux kernel.
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* Copyright (C) 2009-2016 Helge Deller <deller@gmx.de>
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*
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* based on code for x86 which is:
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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*
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* future possible enhancements:
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* - add CONFIG_DYNAMIC_FTRACE
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* - add CONFIG_STACK_TRACER
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*/
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#include <linux/init.h>
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#include <linux/ftrace.h>
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#include <asm/assembly.h>
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#include <asm/sections.h>
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#include <asm/ftrace.h>
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#define __hot __attribute__ ((__section__ (".text.hot")))
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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/*
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* Hook the return address and push it in the stack of return addrs
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* in current thread info.
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*/
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static void __hot prepare_ftrace_return(unsigned long *parent,
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unsigned long self_addr)
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{
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unsigned long old;
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struct ftrace_graph_ent trace;
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extern int parisc_return_to_handler;
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if (unlikely(ftrace_graph_is_dead()))
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return;
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if (unlikely(atomic_read(¤t->tracing_graph_pause)))
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return;
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old = *parent;
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trace.func = self_addr;
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trace.depth = current->curr_ret_stack + 1;
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/* Only trace if the calling function expects to */
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if (!ftrace_graph_entry(&trace))
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return;
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if (ftrace_push_return_trace(old, self_addr, &trace.depth,
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0, NULL) == -EBUSY)
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return;
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/* activate parisc_return_to_handler() as return point */
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*parent = (unsigned long) &parisc_return_to_handler;
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}
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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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void notrace __hot ftrace_function_trampoline(unsigned long parent,
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unsigned long self_addr,
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unsigned long org_sp_gr3)
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{
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extern ftrace_func_t ftrace_trace_function; /* depends on CONFIG_DYNAMIC_FTRACE */
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extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace);
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if (ftrace_trace_function != ftrace_stub) {
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/* struct ftrace_ops *op, struct pt_regs *regs); */
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ftrace_trace_function(parent, self_addr, NULL, NULL);
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return;
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}
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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if (ftrace_graph_return != (trace_func_graph_ret_t) ftrace_stub ||
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ftrace_graph_entry != ftrace_graph_entry_stub) {
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unsigned long *parent_rp;
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/* calculate pointer to %rp in stack */
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parent_rp = (unsigned long *) (org_sp_gr3 - RP_OFFSET);
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/* sanity check: parent_rp should hold parent */
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if (*parent_rp != parent)
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return;
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prepare_ftrace_return(parent_rp, self_addr);
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return;
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}
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#endif
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}
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