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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>
147 lines
3.2 KiB
C
147 lines
3.2 KiB
C
#include <linux/spinlock.h>
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#include <linux/hardirq.h>
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#include <linux/ftrace.h>
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#include <linux/percpu.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <trace/syscall.h>
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#include <asm/ftrace.h>
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#ifdef CONFIG_DYNAMIC_FTRACE
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static const u32 ftrace_nop = 0x01000000;
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static u32 ftrace_call_replace(unsigned long ip, unsigned long addr)
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{
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u32 call;
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s32 off;
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off = ((s32)addr - (s32)ip);
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call = 0x40000000 | ((u32)off >> 2);
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return call;
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}
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static int ftrace_modify_code(unsigned long ip, u32 old, u32 new)
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{
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u32 replaced;
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int faulted;
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__asm__ __volatile__(
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"1: cas [%[ip]], %[old], %[new]\n"
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" flush %[ip]\n"
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" mov 0, %[faulted]\n"
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"2:\n"
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" .section .fixup,#alloc,#execinstr\n"
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" .align 4\n"
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"3: sethi %%hi(2b), %[faulted]\n"
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" jmpl %[faulted] + %%lo(2b), %%g0\n"
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" mov 1, %[faulted]\n"
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" .previous\n"
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" .section __ex_table,\"a\"\n"
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" .align 4\n"
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" .word 1b, 3b\n"
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" .previous\n"
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: "=r" (replaced), [faulted] "=r" (faulted)
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: [new] "0" (new), [old] "r" (old), [ip] "r" (ip)
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: "memory");
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if (replaced != old && replaced != new)
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faulted = 2;
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return faulted;
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}
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int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned long ip = rec->ip;
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u32 old, new;
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old = ftrace_call_replace(ip, addr);
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new = ftrace_nop;
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return ftrace_modify_code(ip, old, new);
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}
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int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned long ip = rec->ip;
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u32 old, new;
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old = ftrace_nop;
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new = ftrace_call_replace(ip, addr);
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return ftrace_modify_code(ip, old, new);
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}
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int ftrace_update_ftrace_func(ftrace_func_t func)
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{
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unsigned long ip = (unsigned long)(&ftrace_call);
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u32 old, new;
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old = *(u32 *) &ftrace_call;
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new = ftrace_call_replace(ip, (unsigned long)func);
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return ftrace_modify_code(ip, old, new);
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}
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int __init ftrace_dyn_arch_init(void)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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#ifdef CONFIG_DYNAMIC_FTRACE
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extern void ftrace_graph_call(void);
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int ftrace_enable_ftrace_graph_caller(void)
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{
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unsigned long ip = (unsigned long)(&ftrace_graph_call);
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u32 old, new;
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old = *(u32 *) &ftrace_graph_call;
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new = ftrace_call_replace(ip, (unsigned long) &ftrace_graph_caller);
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return ftrace_modify_code(ip, old, new);
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}
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int ftrace_disable_ftrace_graph_caller(void)
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{
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unsigned long ip = (unsigned long)(&ftrace_graph_call);
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u32 old, new;
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old = *(u32 *) &ftrace_graph_call;
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new = ftrace_call_replace(ip, (unsigned long) &ftrace_stub);
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return ftrace_modify_code(ip, old, new);
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}
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#endif /* !CONFIG_DYNAMIC_FTRACE */
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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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unsigned long prepare_ftrace_return(unsigned long parent,
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unsigned long self_addr,
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unsigned long frame_pointer)
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{
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unsigned long return_hooker = (unsigned long) &return_to_handler;
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struct ftrace_graph_ent trace;
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if (unlikely(atomic_read(¤t->tracing_graph_pause)))
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return parent + 8UL;
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if (ftrace_push_return_trace(parent, self_addr, &trace.depth,
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frame_pointer, NULL) == -EBUSY)
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return parent + 8UL;
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trace.func = self_addr;
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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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current->curr_ret_stack--;
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return parent + 8UL;
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}
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return return_hooker;
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}
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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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