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Diffstat (limited to 'arch/microblaze/kernel/ftrace.c')
| -rw-r--r-- | arch/microblaze/kernel/ftrace.c | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/arch/microblaze/kernel/ftrace.c b/arch/microblaze/kernel/ftrace.c new file mode 100644 index 0000000..c1889b1 --- /dev/null +++ b/arch/microblaze/kernel/ftrace.c @@ -0,0 +1,151 @@ +/* + * 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 */ |