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/*
* Ftrace support for Microblaze.
*
* Copyright (C) 2009 Michal Simek <monstr@monstr.eu>
* Copyright (C) 2009 PetaLogix
*
* Based on MIPS and PowerPC ftrace code
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <asm/cacheflush.h>
#include <linux/ftrace.h>
#ifdef CONFIG_DYNAMIC_FTRACE
/* save value to addr - it is save to do it in asm */
static int ftrace_modify_code(unsigned long addr, unsigned int value)
{
int faulted = 0;
__asm__ __volatile__(" 1: swi %2, %1, 0; \
addik %0, r0, 0; \
2: \
.section .fixup, \"ax\"; \
3: brid 2b; \
addik %0, r0, 1; \
.previous; \
.section __ex_table,\"a\"; \
.word 1b,3b; \
.previous;" \
: "=r" (faulted)
: "r" (addr), "r" (value)
);
if (unlikely(faulted))
return -EFAULT;
return 0;
}
#define MICROBLAZE_NOP 0x80000000
#define MICROBLAZE_BRI 0xb800000C
static unsigned int recorded; /* if save was or not */
static unsigned int imm; /* saving whole imm instruction */
/* There are two approaches howto solve ftrace_make nop function - look below */
#undef USE_FTRACE_NOP
#ifdef USE_FTRACE_NOP
static unsigned int bralid; /* saving whole bralid instruction */
#endif
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
/* we have this part of code which we are working with
* b000c000 imm -16384
* b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
* 80000000 or r0, r0, r0
*
* The first solution (!USE_FTRACE_NOP-could be called branch solution)
* b000c000 bri 12 (0xC - jump to any other instruction)
* b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount>
* 80000000 or r0, r0, r0
* any other instruction
*
* The second solution (USE_FTRACE_NOP) - no jump just nops
* 80000000 or r0, r0, r0
* 80000000 or r0, r0, r0
* 80000000 or r0, r0, r0
*/
int ret = 0;
if (recorded == 0) {
recorded = 1;
imm = *(unsigned int *)rec->ip;
pr_debug("%s: imm:0x%x\n", __func__, imm);
#ifdef USE_FTRACE_NOP
bralid = *(unsigned int *)(rec->ip + 4);
pr_debug("%s: bralid 0x%x\n", __func__, bralid);
#endif /* USE_FTRACE_NOP */
}
#ifdef USE_FTRACE_NOP
ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP);
ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP);
#else /* USE_FTRACE_NOP */
ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI);
#endif /* USE_FTRACE_NOP */
return ret;
}
static int ret_addr; /* initialized as 0 by default */
/* I believe that first is called ftrace_make_nop before this function */
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
int ret;
ret_addr = addr; /* saving where the barrier jump is */
pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n",
__func__, (unsigned int)addr, (unsigned int)rec->ip, imm);
ret = ftrace_modify_code(rec->ip, imm);
#ifdef USE_FTRACE_NOP
pr_debug("%s: bralid:0x%x\n", __func__, bralid);
ret += ftrace_modify_code(rec->ip + 4, bralid);
#endif /* USE_FTRACE_NOP */
return ret;
}
int __init ftrace_dyn_arch_init(void *data)
{
/* The return code is retured via data */
*(unsigned long *)data = 0;
return 0;
}
int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned long ip = (unsigned long)(&ftrace_call);
unsigned int upper = (unsigned int)func;
unsigned int lower = (unsigned int)func;
int ret = 0;
/* create proper saving to ftrace_call poll */
upper = 0xb0000000 + (upper >> 16); /* imm func_upper */
lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */
pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n",
__func__, (unsigned int)func, (unsigned int)ip, upper, lower);
/* save upper and lower code */
ret = ftrace_modify_code(ip, upper);
ret += ftrace_modify_code(ip + 4, lower);
/* We just need to remove the rtsd r15, 8 by NOP */
BUG_ON(!ret_addr);
if (ret_addr)
ret += ftrace_modify_code(ret_addr, MICROBLAZE_NOP);
else
ret = 1; /* fault */
/* All changes are done - lets do caches consistent */
flush_icache();
return ret;
}
#endif /* CONFIG_DYNAMIC_FTRACE */
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