diff options
Diffstat (limited to 'arch/s390/kernel')
| -rw-r--r-- | arch/s390/kernel/ftrace.c | 238 | ||||
| -rw-r--r-- | arch/s390/kernel/mcount.S | 30 | ||||
| -rw-r--r-- | arch/s390/kernel/mcount64.S | 27 |
3 files changed, 131 insertions, 164 deletions
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c index 6a83d05..78bdf0e 100644 --- a/arch/s390/kernel/ftrace.c +++ b/arch/s390/kernel/ftrace.c @@ -4,7 +4,7 @@ * Copyright IBM Corp. 2009 * * Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>, - * + * Martin Schwidefsky <schwidefsky@de.ibm.com> */ #include <linux/hardirq.h> @@ -12,176 +12,144 @@ #include <linux/ftrace.h> #include <linux/kernel.h> #include <linux/types.h> +#include <linux/kprobes.h> #include <trace/syscall.h> #include <asm/asm-offsets.h> +#ifdef CONFIG_64BIT +#define MCOUNT_OFFSET_RET 12 +#else +#define MCOUNT_OFFSET_RET 22 +#endif + #ifdef CONFIG_DYNAMIC_FTRACE void ftrace_disable_code(void); -void ftrace_disable_return(void); -void ftrace_call_code(void); -void ftrace_nop_code(void); - -#define FTRACE_INSN_SIZE 4 +void ftrace_enable_insn(void); #ifdef CONFIG_64BIT - +/* + * The 64-bit mcount code looks like this: + * stg %r14,8(%r15) # offset 0 + * > larl %r1,<&counter> # offset 6 + * > brasl %r14,_mcount # offset 12 + * lg %r14,8(%r15) # offset 18 + * Total length is 24 bytes. The middle two instructions of the mcount + * block get overwritten by ftrace_make_nop / ftrace_make_call. + * The 64-bit enabled ftrace code block looks like this: + * stg %r14,8(%r15) # offset 0 + * > lg %r1,__LC_FTRACE_FUNC # offset 6 + * > lgr %r0,%r0 # offset 12 + * > basr %r14,%r1 # offset 16 + * lg %r14,8(%15) # offset 18 + * The return points of the mcount/ftrace function have the same offset 18. + * The 64-bit disable ftrace code block looks like this: + * stg %r14,8(%r15) # offset 0 + * > jg .+18 # offset 6 + * > lgr %r0,%r0 # offset 12 + * > basr %r14,%r1 # offset 16 + * lg %r14,8(%15) # offset 18 + * The jg instruction branches to offset 24 to skip as many instructions + * as possible. + */ asm( " .align 4\n" "ftrace_disable_code:\n" - " j 0f\n" - " .word 0x0024\n" - " lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n" - " basr %r14,%r1\n" - "ftrace_disable_return:\n" - " lg %r14,8(15)\n" + " jg 0f\n" " lgr %r0,%r0\n" - "0:\n"); - -asm( + " basr %r14,%r1\n" + "0:\n" " .align 4\n" - "ftrace_nop_code:\n" - " j .+"__stringify(MCOUNT_INSN_SIZE)"\n"); + "ftrace_enable_insn:\n" + " lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n"); -asm( - " .align 4\n" - "ftrace_call_code:\n" - " stg %r14,8(%r15)\n"); +#define FTRACE_INSN_SIZE 6 #else /* CONFIG_64BIT */ - +/* + * The 31-bit mcount code looks like this: + * st %r14,4(%r15) # offset 0 + * > bras %r1,0f # offset 4 + * > .long _mcount # offset 8 + * > .long <&counter> # offset 12 + * > 0: l %r14,0(%r1) # offset 16 + * > l %r1,4(%r1) # offset 20 + * basr %r14,%r14 # offset 24 + * l %r14,4(%r15) # offset 26 + * Total length is 30 bytes. The twenty bytes starting from offset 4 + * to offset 24 get overwritten by ftrace_make_nop / ftrace_make_call. + * The 31-bit enabled ftrace code block looks like this: + * st %r14,4(%r15) # offset 0 + * > l %r14,__LC_FTRACE_FUNC # offset 4 + * > j 0f # offset 8 + * > .fill 12,1,0x07 # offset 12 + * 0: basr %r14,%r14 # offset 24 + * l %r14,4(%r14) # offset 26 + * The return points of the mcount/ftrace function have the same offset 26. + * The 31-bit disabled ftrace code block looks like this: + * st %r14,4(%r15) # offset 0 + * > j .+26 # offset 4 + * > j 0f # offset 8 + * > .fill 12,1,0x07 # offset 12 + * 0: basr %r14,%r14 # offset 24 + * l %r14,4(%r14) # offset 26 + * The j instruction branches to offset 30 to skip as many instructions + * as possible. + */ asm( " .align 4\n" "ftrace_disable_code:\n" + " j 1f\n" " j 0f\n" - " l %r1,"__stringify(__LC_FTRACE_FUNC)"\n" - " basr %r14,%r1\n" - "ftrace_disable_return:\n" - " l %r14,4(%r15)\n" - " j 0f\n" - " bcr 0,%r7\n" - " bcr 0,%r7\n" - " bcr 0,%r7\n" - " bcr 0,%r7\n" - " bcr 0,%r7\n" - " bcr 0,%r7\n" - "0:\n"); - -asm( + " .fill 12,1,0x07\n" + "0: basr %r14,%r14\n" + "1:\n" " .align 4\n" - "ftrace_nop_code:\n" - " j .+"__stringify(MCOUNT_INSN_SIZE)"\n"); + "ftrace_enable_insn:\n" + " l %r14,"__stringify(__LC_FTRACE_FUNC)"\n"); -asm( - " .align 4\n" - "ftrace_call_code:\n" - " st %r14,4(%r15)\n"); +#define FTRACE_INSN_SIZE 4 #endif /* CONFIG_64BIT */ -static int ftrace_modify_code(unsigned long ip, - void *old_code, int old_size, - void *new_code, int new_size) -{ - unsigned char replaced[MCOUNT_INSN_SIZE]; - - /* - * Note: Due to modules code can disappear and change. - * We need to protect against faulting as well as code - * changing. We do this by using the probe_kernel_* - * functions. - * This however is just a simple sanity check. - */ - if (probe_kernel_read(replaced, (void *)ip, old_size)) - return -EFAULT; - if (memcmp(replaced, old_code, old_size) != 0) - return -EINVAL; - if (probe_kernel_write((void *)ip, new_code, new_size)) - return -EPERM; - return 0; -} - -static int ftrace_make_initial_nop(struct module *mod, struct dyn_ftrace *rec, - unsigned long addr) -{ - return ftrace_modify_code(rec->ip, - ftrace_call_code, FTRACE_INSN_SIZE, - ftrace_disable_code, MCOUNT_INSN_SIZE); -} int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { - if (addr == MCOUNT_ADDR) - return ftrace_make_initial_nop(mod, rec, addr); - return ftrace_modify_code(rec->ip, - ftrace_call_code, FTRACE_INSN_SIZE, - ftrace_nop_code, FTRACE_INSN_SIZE); + if (probe_kernel_write((void *) rec->ip, ftrace_disable_code, + MCOUNT_INSN_SIZE)) + return -EPERM; + return 0; } int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { - return ftrace_modify_code(rec->ip, - ftrace_nop_code, FTRACE_INSN_SIZE, - ftrace_call_code, FTRACE_INSN_SIZE); + if (probe_kernel_write((void *) rec->ip, ftrace_enable_insn, + FTRACE_INSN_SIZE)) + return -EPERM; + return 0; } int ftrace_update_ftrace_func(ftrace_func_t func) { - ftrace_dyn_func = (unsigned long)func; return 0; } int __init ftrace_dyn_arch_init(void *data) { - *(unsigned long *)data = 0; + *(unsigned long *) data = 0; return 0; } #endif /* CONFIG_DYNAMIC_FTRACE */ #ifdef CONFIG_FUNCTION_GRAPH_TRACER -#ifdef CONFIG_DYNAMIC_FTRACE -/* - * Patch the kernel code at ftrace_graph_caller location: - * The instruction there is branch relative on condition. The condition mask - * is either all ones (always branch aka disable ftrace_graph_caller) or all - * zeroes (nop aka enable ftrace_graph_caller). - * Instruction format for brc is a7m4xxxx where m is the condition mask. - */ -int ftrace_enable_ftrace_graph_caller(void) -{ - unsigned short opcode = 0xa704; - - return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode)); -} - -int ftrace_disable_ftrace_graph_caller(void) -{ - unsigned short opcode = 0xa7f4; - - return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode)); -} - -static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr) -{ - return addr - (ftrace_disable_return - ftrace_disable_code); -} - -#else /* CONFIG_DYNAMIC_FTRACE */ - -static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr) -{ - return addr - MCOUNT_OFFSET_RET; -} - -#endif /* CONFIG_DYNAMIC_FTRACE */ - /* * Hook the return address and push it in the stack of return addresses * in current thread info. */ -unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent) +unsigned long __kprobes prepare_ftrace_return(unsigned long parent, + unsigned long ip) { struct ftrace_graph_ent trace; @@ -189,14 +157,42 @@ unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent) goto out; if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY) goto out; - trace.func = ftrace_mcount_call_adjust(ip) & PSW_ADDR_INSN; + trace.func = (ip & PSW_ADDR_INSN) - MCOUNT_OFFSET_RET; /* Only trace if the calling function expects to. */ if (!ftrace_graph_entry(&trace)) { current->curr_ret_stack--; goto out; } - parent = (unsigned long)return_to_handler; + parent = (unsigned long) return_to_handler; out: return parent; } + +#ifdef CONFIG_DYNAMIC_FTRACE +/* + * Patch the kernel code at ftrace_graph_caller location. The instruction + * there is branch relative and save to prepare_ftrace_return. To disable + * the call to prepare_ftrace_return we patch the bras offset to point + * directly after the instructions. To enable the call we calculate + * the original offset to prepare_ftrace_return and put it back. + */ +int ftrace_enable_ftrace_graph_caller(void) +{ + unsigned short offset; + + offset = ((void *) prepare_ftrace_return - + (void *) ftrace_graph_caller) / 2; + return probe_kernel_write(ftrace_graph_caller + 2, + &offset, sizeof(offset)); +} + +int ftrace_disable_ftrace_graph_caller(void) +{ + static unsigned short offset = 0x0002; + + return probe_kernel_write(ftrace_graph_caller + 2, + &offset, sizeof(offset)); +} + +#endif /* CONFIG_DYNAMIC_FTRACE */ #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S index 4a6e1a5..1e6a557 100644 --- a/arch/s390/kernel/mcount.S +++ b/arch/s390/kernel/mcount.S @@ -18,22 +18,12 @@ _mcount: #ifdef CONFIG_DYNAMIC_FTRACE br %r14 - .data - .globl ftrace_dyn_func -ftrace_dyn_func: - .long ftrace_stub - .previous - .globl ftrace_caller ftrace_caller: #endif stm %r2,%r5,16(%r15) bras %r1,2f -#ifdef CONFIG_DYNAMIC_FTRACE -0: .long ftrace_dyn_func -#else 0: .long ftrace_trace_function -#endif 1: .long function_trace_stop 2: l %r2,1b-0b(%r1) icm %r2,0xf,0(%r2) @@ -49,21 +39,15 @@ ftrace_caller: l %r14,0(%r14) basr %r14,%r14 #ifdef CONFIG_FUNCTION_GRAPH_TRACER -#ifdef CONFIG_DYNAMIC_FTRACE + l %r2,100(%r15) + l %r3,152(%r15) .globl ftrace_graph_caller ftrace_graph_caller: - # This unconditional branch gets runtime patched. Change only if - # you know what you are doing. See ftrace_enable_graph_caller(). - j 1f -#endif - bras %r1,0f - .long prepare_ftrace_return -0: l %r2,152(%r15) - l %r4,0(%r1) - l %r3,100(%r15) - basr %r14,%r4 - st %r2,100(%r15) -1: +# The bras instruction gets runtime patched to call prepare_ftrace_return. +# See ftrace_enable_ftrace_graph_caller. The patched instruction is: +# bras %r14,prepare_ftrace_return + bras %r14,0f +0: st %r2,100(%r15) #endif ahi %r15,96 l %r14,56(%r15) diff --git a/arch/s390/kernel/mcount64.S b/arch/s390/kernel/mcount64.S index b2bae06..e736672 100644 --- a/arch/s390/kernel/mcount64.S +++ b/arch/s390/kernel/mcount64.S @@ -18,12 +18,6 @@ _mcount: #ifdef CONFIG_DYNAMIC_FTRACE br %r14 - .data - .globl ftrace_dyn_func -ftrace_dyn_func: - .quad ftrace_stub - .previous - .globl ftrace_caller ftrace_caller: #endif @@ -37,26 +31,19 @@ ftrace_caller: stg %r1,__SF_BACKCHAIN(%r15) lgr %r2,%r14 lg %r3,168(%r15) -#ifdef CONFIG_DYNAMIC_FTRACE - larl %r14,ftrace_dyn_func -#else larl %r14,ftrace_trace_function -#endif lg %r14,0(%r14) basr %r14,%r14 #ifdef CONFIG_FUNCTION_GRAPH_TRACER -#ifdef CONFIG_DYNAMIC_FTRACE + lg %r2,168(%r15) + lg %r3,272(%r15) .globl ftrace_graph_caller ftrace_graph_caller: - # This unconditional branch gets runtime patched. Change only if - # you know what you are doing. See ftrace_enable_graph_caller(). - j 0f -#endif - lg %r2,272(%r15) - lg %r3,168(%r15) - brasl %r14,prepare_ftrace_return - stg %r2,168(%r15) -0: +# The bras instruction gets runtime patched to call prepare_ftrace_return. +# See ftrace_enable_ftrace_graph_caller. The patched instruction is: +# bras %r14,prepare_ftrace_return + bras %r14,0f +0: stg %r2,168(%r15) #endif aghi %r15,160 lmg %r2,%r5,32(%r15) |