Impact: Implement PPC64 module trampolines for dyn ftrace This adds code to handle the PPC64 module trampolines, and allows for PPC64 to use dynamic ftrace. Signed-off-by: Steven Rostedt --- arch/powerpc/include/asm/ftrace.h | 3 +- arch/powerpc/include/asm/module.h | 11 ++ arch/powerpc/kernel/ftrace.c | 202 +++++++++++++++++++++++++++++++++++-- arch/powerpc/kernel/module_64.c | 13 +++ 4 files changed, 220 insertions(+), 9 deletions(-) diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index 17efecc..d57f5bc 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -16,7 +16,8 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) } struct dyn_arch_ftrace { - /* nothing yet */ + struct module *mod; + unsigned long tramp; }; #endif /* CONFIG_DYNAMIC_FTRACE */ #endif /* __ASSEMBLY__ */ diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h index e5f14b1..340bc69 100644 --- a/arch/powerpc/include/asm/module.h +++ b/arch/powerpc/include/asm/module.h @@ -34,6 +34,11 @@ struct mod_arch_specific { #ifdef __powerpc64__ unsigned int stubs_section; /* Index of stubs section in module */ unsigned int toc_section; /* What section is the TOC? */ +#ifdef CONFIG_DYNAMIC_FTRACE + unsigned long toc; + unsigned long tramp; +#endif + #else /* Indices of PLT sections within module. */ unsigned int core_plt_section; @@ -68,6 +73,12 @@ struct mod_arch_specific { # endif /* MODULE */ #endif +#ifdef CONFIG_DYNAMIC_FTRACE +# ifdef MODULE + asm(".section .ftrace.tramp,\"ax\",@nobits; .align 3; .previous"); +# endif /* MODULE */ +#endif + struct exception_table_entry; void sort_ex_table(struct exception_table_entry *start, diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c index 3852919..acbec66 100644 --- a/arch/powerpc/kernel/ftrace.c +++ b/arch/powerpc/kernel/ftrace.c @@ -10,22 +10,29 @@ #include #include #include +#include #include #include #include #include #include +#include #include +#if 0 +#define DEBUGP printk +#else +#define DEBUGP(fmt , ...) do { } while (0) +#endif -static unsigned int ftrace_nop = 0x60000000; +static unsigned int ftrace_nop = PPC_NOP_INSTR; #ifdef CONFIG_PPC32 # define GET_ADDR(addr) addr #else /* PowerPC64's functions are data that points to the functions */ -# define GET_ADDR(addr) *(unsigned long *)addr +# define GET_ADDR(addr) (*(unsigned long *)addr) #endif @@ -115,40 +122,219 @@ static int test_24bit_addr(unsigned long ip, unsigned long addr) int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { + unsigned char replaced[MCOUNT_INSN_SIZE * 2]; + unsigned int *op = (unsigned *)&replaced; + unsigned char jmp[8]; + unsigned long *ptr = (unsigned long *)&jmp; unsigned char *old, *new; + unsigned long ip = rec->ip; + unsigned long tramp; + int offset; /* * If the calling address is more that 24 bits away, * then we had to use a trampoline to make the call. * Otherwise just update the call site. */ - if (test_24bit_addr(rec->ip, addr)) { + if (test_24bit_addr(ip, addr)) { /* within range */ - old = ftrace_call_replace(rec->ip, addr); + old = ftrace_call_replace(ip, addr); new = ftrace_nop_replace(); - return ftrace_modify_code(rec->ip, old, new); + return ftrace_modify_code(ip, old, new); } +#ifndef CONFIG_PPC64 + /* only supported for PPC64 for now */ return 0; +#else + + /* + * Out of range jumps are called from modules. + * We should either already have a pointer to the module + * or it has been passed in. + */ + if (!rec->arch.mod) { + if (!mod) { + printk(KERN_ERR "No module loaded addr=%lx\n", + addr); + return -EFAULT; + } + rec->arch.mod = mod; + } else if (mod) { + printk(KERN_ERR + "Record mod %p not equal to passed in mod %p\n", + rec->arch.mod, mod); + return -EINVAL; + } else + mod = rec->arch.mod; + + /* read where this goes */ + if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE)) + return -EFAULT; + + /* Make sure that that this is still a 24bit jump */ + if ((*op & 0xff000000) != 0x48000000) { + printk(KERN_ERR "Not expected bl: opcode is %x\n", *op); + return -EINVAL; + } + + /* lets find where the pointer goes */ + offset = (*op & 0x03fffffc); + /* make it signed */ + if (offset & 0x02000000) + offset |= 0xfe000000; + + tramp = ip + (long)offset; + + /* + * On PPC64 the trampoline looks like: + * 0x3d, 0x82, 0x00, 0x00, addis r12,r2, + * 0x39, 0x8c, 0x00, 0x00, addi r12,r12, + * Where the bytes 2,3,6 and 7 make up the 32bit offset + * to the TOC that holds the pointer. + * to jump to. + * 0xf8, 0x41, 0x00, 0x28, std r2,40(r1) + * 0xe9, 0x6c, 0x00, 0x20, ld r11,32(r12) + * The actually address is 32 bytes from the offset + * into the TOC. + * 0xe8, 0x4c, 0x00, 0x28, ld r2,40(r12) + */ + + DEBUGP("ip:%lx jumps to %lx r2: %lx", ip, tramp, mod->arch.toc); + + /* Find where the trampoline jumps to */ + if (probe_kernel_read(jmp, (void *)tramp, 8)) { + printk(KERN_ERR "Failed to read %lx\n", tramp); + return -EFAULT; + } + + DEBUGP(" %08x %08x", + (unsigned)(*ptr >> 32), + (unsigned)*ptr); + + offset = (unsigned)jmp[2] << 24 | + (unsigned)jmp[3] << 16 | + (unsigned)jmp[6] << 8 | + (unsigned)jmp[7]; + + DEBUGP(" %x ", offset); + + /* get the address this jumps too */ + tramp = mod->arch.toc + offset + 32; + DEBUGP("toc: %lx", tramp); + + if (probe_kernel_read(jmp, (void *)tramp, 8)) { + printk(KERN_ERR "Failed to read %lx\n", tramp); + return -EFAULT; + } + + DEBUGP(" %08x %08x\n", + (unsigned)(*ptr >> 32), + (unsigned)*ptr); + + /* This should match what was called */ + if (*ptr != GET_ADDR(addr)) { + printk(KERN_ERR "addr does not match %lx\n", *ptr); + return -EINVAL; + } + + /* + * We want to nop the line, but the next line is + * 0xe8, 0x41, 0x00, 0x28 ld r2,40(r1) + * This needs to be turned to a nop too. + */ + if (probe_kernel_read(replaced, (void *)(ip+4), MCOUNT_INSN_SIZE)) + return -EFAULT; + + if (*op != 0xe8410028) { + printk(KERN_ERR "Next line is not ld! (%08x)\n", *op); + return -EINVAL; + } + + op[0] = PPC_NOP_INSTR; + op[1] = PPC_NOP_INSTR; + + if (probe_kernel_write((void *)ip, replaced, MCOUNT_INSN_SIZE * 2)) + return -EPERM; + + return 0; +#endif /* CONFIG_PPC64 */ } int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { + unsigned char replaced[MCOUNT_INSN_SIZE * 2]; + unsigned int *op = (unsigned *)&replaced; unsigned char *old, *new; + unsigned long ip = rec->ip; + unsigned long offset; /* * If the calling address is more that 24 bits away, * then we had to use a trampoline to make the call. * Otherwise just update the call site. */ - if (test_24bit_addr(rec->ip, addr)) { + if (test_24bit_addr(ip, addr)) { /* within range */ old = ftrace_nop_replace(); - new = ftrace_call_replace(rec->ip, addr); - return ftrace_modify_code(rec->ip, old, new); + new = ftrace_call_replace(ip, addr); + return ftrace_modify_code(ip, old, new); } +#ifndef CONFIG_PPC64 + /* only supported for PPC64 for now */ + return 0; +#else + + /* + * Out of range jumps are called from modules. + * Being that we are converting from nop, it had better + * already have a module defined. + */ + if (!rec->arch.mod) { + printk(KERN_ERR "No module loaded\n"); + return -EINVAL; + } + + /* read where this goes */ + if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE * 2)) + return -EFAULT; + + /* It should be pointing to two nops */ + if ((op[0] != PPC_NOP_INSTR) || + (op[1] != PPC_NOP_INSTR)) { + printk(KERN_ERR "Expected NOPs but have %x %x\n", op[0], op[1]); + return -EINVAL; + } + + /* If we never set up a trampoline to ftrace_caller, then bail */ + if (!rec->arch.mod->arch.tramp) { + printk(KERN_ERR "No ftrace trampoline\n"); + return -EINVAL; + } + + /* now calculate a jump to the ftrace caller trampoline */ + offset = rec->arch.mod->arch.tramp - ip; + + if (offset + 0x2000000 > 0x3ffffff || (offset & 3) != 0) { + printk(KERN_ERR "REL24 %li out of range!\n", + (long int)offset); + return -EINVAL; + } + + + /* Set to "bl addr" */ + op[0] = 0x48000001 | (offset & 0x03fffffc); + /* ld r2,40(r1) */ + op[1] = 0xe8410028; + + DEBUGP("write to %lx\n", rec->ip); + + if (probe_kernel_write((void *)ip, replaced, MCOUNT_INSN_SIZE * 2)) + return -EPERM; + return 0; +#endif /* CONFIG_PPC64 */ } int ftrace_update_ftrace_func(ftrace_func_t func) diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index 1af2377..8992b03 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -163,6 +164,11 @@ static unsigned long get_stubs_size(const Elf64_Ehdr *hdr, } } +#ifdef CONFIG_DYNAMIC_FTRACE + /* make the trampoline to the ftrace_caller */ + relocs++; +#endif + DEBUGP("Looks like a total of %lu stubs, max\n", relocs); return relocs * sizeof(struct ppc64_stub_entry); } @@ -441,5 +447,12 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, } } +#ifdef CONFIG_DYNAMIC_FTRACE + me->arch.toc = my_r2(sechdrs, me); + me->arch.tramp = stub_for_addr(sechdrs, + (unsigned long)ftrace_caller, + me); +#endif + return 0; } -- 1.5.6.5 -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/