e1dc5007cf
ftrace_stop() is going away as it disables parts of function tracing that affects users that should not be affected. But ftrace_graph_stop() is built on ftrace_stop(). Here's another example of killing all of function tracing because something went wrong with function graph tracing. Instead of disabling all users of function tracing on function graph error, disable only function graph tracing. To do this, the arch code must call ftrace_graph_is_dead() before it implements function graph. Link: http://lkml.kernel.org/r/53C8D874.9090601@monstr.eu Tested-by: Michal Simek <monstr@monstr.eu> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
234 lines
6.1 KiB
C
234 lines
6.1 KiB
C
/*
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* Ftrace support for Microblaze.
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*
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* Copyright (C) 2009 Michal Simek <monstr@monstr.eu>
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* Copyright (C) 2009 PetaLogix
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*
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* Based on MIPS and PowerPC ftrace code
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <asm/cacheflush.h>
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#include <linux/ftrace.h>
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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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void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
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{
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unsigned long old;
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int faulted, err;
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struct ftrace_graph_ent trace;
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unsigned long return_hooker = (unsigned long)
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&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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/*
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* Protect against fault, even if it shouldn't
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* happen. This tool is too much intrusive to
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* ignore such a protection.
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*/
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asm volatile(" 1: lwi %0, %2, 0;" \
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"2: swi %3, %2, 0;" \
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" addik %1, r0, 0;" \
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"3:" \
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" .section .fixup, \"ax\";" \
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"4: brid 3b;" \
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" addik %1, r0, 1;" \
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" .previous;" \
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" .section __ex_table,\"a\";" \
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" .word 1b,4b;" \
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" .word 2b,4b;" \
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" .previous;" \
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: "=&r" (old), "=r" (faulted)
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: "r" (parent), "r" (return_hooker)
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);
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flush_dcache_range((u32)parent, (u32)parent + 4);
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flush_icache_range((u32)parent, (u32)parent + 4);
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if (unlikely(faulted)) {
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ftrace_graph_stop();
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WARN_ON(1);
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return;
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}
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err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0);
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if (err == -EBUSY) {
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*parent = old;
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return;
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}
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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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*parent = old;
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}
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}
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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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#ifdef CONFIG_DYNAMIC_FTRACE
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/* save value to addr - it is save to do it in asm */
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static int ftrace_modify_code(unsigned long addr, unsigned int value)
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{
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int faulted = 0;
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__asm__ __volatile__(" 1: swi %2, %1, 0;" \
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" addik %0, r0, 0;" \
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"2:" \
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" .section .fixup, \"ax\";" \
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"3: brid 2b;" \
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" addik %0, r0, 1;" \
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" .previous;" \
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" .section __ex_table,\"a\";" \
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" .word 1b,3b;" \
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" .previous;" \
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: "=r" (faulted)
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: "r" (addr), "r" (value)
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);
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if (unlikely(faulted))
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return -EFAULT;
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flush_dcache_range(addr, addr + 4);
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flush_icache_range(addr, addr + 4);
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return 0;
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}
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#define MICROBLAZE_NOP 0x80000000
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#define MICROBLAZE_BRI 0xb800000C
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static unsigned int recorded; /* if save was or not */
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static unsigned int imm; /* saving whole imm instruction */
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/* There are two approaches howto solve ftrace_make nop function - look below */
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#undef USE_FTRACE_NOP
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#ifdef USE_FTRACE_NOP
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static unsigned int bralid; /* saving whole bralid instruction */
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#endif
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int ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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/* we have this part of code which we are working with
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* b000c000 imm -16384
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* b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
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* 80000000 or r0, r0, r0
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*
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* The first solution (!USE_FTRACE_NOP-could be called branch solution)
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* b000c000 bri 12 (0xC - jump to any other instruction)
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* b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
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* 80000000 or r0, r0, r0
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* any other instruction
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*
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* The second solution (USE_FTRACE_NOP) - no jump just nops
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* 80000000 or r0, r0, r0
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* 80000000 or r0, r0, r0
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* 80000000 or r0, r0, r0
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*/
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int ret = 0;
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if (recorded == 0) {
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recorded = 1;
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imm = *(unsigned int *)rec->ip;
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pr_debug("%s: imm:0x%x\n", __func__, imm);
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#ifdef USE_FTRACE_NOP
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bralid = *(unsigned int *)(rec->ip + 4);
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pr_debug("%s: bralid 0x%x\n", __func__, bralid);
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#endif /* USE_FTRACE_NOP */
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}
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#ifdef USE_FTRACE_NOP
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ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP);
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ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP);
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#else /* USE_FTRACE_NOP */
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ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI);
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#endif /* USE_FTRACE_NOP */
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return ret;
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}
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/* I believe that first is called ftrace_make_nop before this function */
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int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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int ret;
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pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n",
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__func__, (unsigned int)addr, (unsigned int)rec->ip, imm);
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ret = ftrace_modify_code(rec->ip, imm);
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#ifdef USE_FTRACE_NOP
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pr_debug("%s: bralid:0x%x\n", __func__, bralid);
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ret += ftrace_modify_code(rec->ip + 4, bralid);
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#endif /* USE_FTRACE_NOP */
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return ret;
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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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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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unsigned int upper = (unsigned int)func;
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unsigned int lower = (unsigned int)func;
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int ret = 0;
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/* create proper saving to ftrace_call poll */
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upper = 0xb0000000 + (upper >> 16); /* imm func_upper */
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lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */
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pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n",
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__func__, (unsigned int)func, (unsigned int)ip, upper, lower);
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/* save upper and lower code */
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ret = ftrace_modify_code(ip, upper);
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ret += ftrace_modify_code(ip + 4, lower);
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/* We just need to replace the rtsd r15, 8 with NOP */
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ret += ftrace_modify_code((unsigned long)&ftrace_caller,
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MICROBLAZE_NOP);
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return ret;
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}
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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unsigned int old_jump; /* saving place for jump instruction */
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int ftrace_enable_ftrace_graph_caller(void)
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{
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unsigned int ret;
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unsigned long ip = (unsigned long)(&ftrace_call_graph);
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old_jump = *(unsigned int *)ip; /* save jump over instruction */
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ret = ftrace_modify_code(ip, MICROBLAZE_NOP);
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pr_debug("%s: Replace instruction: 0x%x\n", __func__, old_jump);
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return ret;
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}
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int ftrace_disable_ftrace_graph_caller(void)
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{
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unsigned int ret;
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unsigned long ip = (unsigned long)(&ftrace_call_graph);
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ret = ftrace_modify_code(ip, old_jump);
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pr_debug("%s\n", __func__);
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return ret;
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}
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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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#endif /* CONFIG_DYNAMIC_FTRACE */
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