From: Ananth N Mavinakayanahalli In an effort to make kprobe modules more portable, here is a patch that: o Introduces the "symbol_name" field to struct kprobe. The symbol->address resolution now happens in the kernel in an architecture agnostic manner. 64-bit powerpc users no longer have to specify the ".symbols" o Introduces the "offset" field to struct kprobe to allow a user to specify an offset into a symbol. o The legacy mechanism of specifying the kprobe.addr is still supported. However, if both the kprobe.addr and kprobe.symbol_name are specified, probe registration fails with an -EINVAL. o The symbol resolution code uses kallsyms_lookup_name(). So CONFIG_KPROBES now depends on CONFIG_KALLSYMS o Apparantly kprobe modules were the only legitimate out-of-tree user of the kallsyms_lookup_name() EXPORT. Now that the symbol resolution happens in-kernel, remove the EXPORT as suggested by Christoph Hellwig o Modify tcp_probe.c that uses the kprobe interface so as to make it work on multiple platforms (in its earlier form, the code wouldn't work, say, on powerpc) Signed-off-by: Ananth N Mavinakayanahalli Signed-off-by: Prasanna S Panchamukhi Signed-off-by: Christoph Hellwig Signed-off-by: Andrew Morton --- arch/i386/Kconfig | 2 +- arch/ia64/Kconfig | 2 +- arch/powerpc/Kconfig | 2 +- arch/sparc64/Kconfig | 2 +- arch/x86_64/Kconfig | 2 +- include/asm-powerpc/kprobes.h | 3 +++ include/linux/kprobes.h | 6 ++++++ kernel/kallsyms.c | 1 - kernel/kprobes.c | 26 ++++++++++++++++++++++++++ net/ipv4/tcp_probe.c | 6 ++++-- 10 files changed, 44 insertions(+), 8 deletions(-) diff -puN arch/i386/Kconfig~kprobes-make-kprobe-modules-more-portable arch/i386/Kconfig --- a/arch/i386/Kconfig~kprobes-make-kprobe-modules-more-portable +++ a/arch/i386/Kconfig @@ -1164,7 +1164,7 @@ source "arch/i386/oprofile/Kconfig" config KPROBES bool "Kprobes (EXPERIMENTAL)" - depends on EXPERIMENTAL && MODULES + depends on KALLSYMS && EXPERIMENTAL && MODULES help Kprobes allows you to trap at almost any kernel address and execute a callback function. register_kprobe() establishes diff -puN arch/ia64/Kconfig~kprobes-make-kprobe-modules-more-portable arch/ia64/Kconfig --- a/arch/ia64/Kconfig~kprobes-make-kprobe-modules-more-portable +++ a/arch/ia64/Kconfig @@ -535,7 +535,7 @@ source "arch/ia64/oprofile/Kconfig" config KPROBES bool "Kprobes (EXPERIMENTAL)" - depends on EXPERIMENTAL && MODULES + depends on KALLSYMS && EXPERIMENTAL && MODULES help Kprobes allows you to trap at almost any kernel address and execute a callback function. register_kprobe() establishes diff -puN arch/powerpc/Kconfig~kprobes-make-kprobe-modules-more-portable arch/powerpc/Kconfig --- a/arch/powerpc/Kconfig~kprobes-make-kprobe-modules-more-portable +++ a/arch/powerpc/Kconfig @@ -1054,7 +1054,7 @@ source "arch/powerpc/oprofile/Kconfig" config KPROBES bool "Kprobes (EXPERIMENTAL)" - depends on PPC64 && EXPERIMENTAL && MODULES + depends on PPC64 && KALLSYMS && EXPERIMENTAL && MODULES help Kprobes allows you to trap at almost any kernel address and execute a callback function. register_kprobe() establishes diff -puN arch/sparc64/Kconfig~kprobes-make-kprobe-modules-more-portable arch/sparc64/Kconfig --- a/arch/sparc64/Kconfig~kprobes-make-kprobe-modules-more-portable +++ a/arch/sparc64/Kconfig @@ -416,7 +416,7 @@ source "arch/sparc64/oprofile/Kconfig" config KPROBES bool "Kprobes (EXPERIMENTAL)" - depends on EXPERIMENTAL && MODULES + depends on KALLSYMS && EXPERIMENTAL && MODULES help Kprobes allows you to trap at almost any kernel address and execute a callback function. register_kprobe() establishes diff -puN arch/x86_64/Kconfig~kprobes-make-kprobe-modules-more-portable arch/x86_64/Kconfig --- a/arch/x86_64/Kconfig~kprobes-make-kprobe-modules-more-portable +++ a/arch/x86_64/Kconfig @@ -675,7 +675,7 @@ source "arch/x86_64/oprofile/Kconfig" config KPROBES bool "Kprobes (EXPERIMENTAL)" - depends on EXPERIMENTAL && MODULES + depends on KALLSYMS && EXPERIMENTAL && MODULES help Kprobes allows you to trap at almost any kernel address and execute a callback function. register_kprobe() establishes diff -puN include/asm-powerpc/kprobes.h~kprobes-make-kprobe-modules-more-portable include/asm-powerpc/kprobes.h --- a/include/asm-powerpc/kprobes.h~kprobes-make-kprobe-modules-more-portable +++ a/include/asm-powerpc/kprobes.h @@ -44,6 +44,9 @@ typedef unsigned int kprobe_opcode_t; #define IS_TDI(instr) (((instr) & 0xfc000000) == 0x08000000) #define IS_TWI(instr) (((instr) & 0xfc000000) == 0x0c000000) +#define kprobe_lookup_name(name) \ + (*((kprobe_opcode_t **)kallsyms_lookup_name(name))) + #define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)((func_descr_t *)pentry) #define is_trap(instr) (IS_TW(instr) || IS_TD(instr) || \ diff -puN include/linux/kprobes.h~kprobes-make-kprobe-modules-more-portable include/linux/kprobes.h --- a/include/linux/kprobes.h~kprobes-make-kprobe-modules-more-portable +++ a/include/linux/kprobes.h @@ -77,6 +77,12 @@ struct kprobe { /* location of the probe point */ kprobe_opcode_t *addr; + /* Allow user to indicate symbol name of the probe point */ + char *symbol_name; + + /* Offset into the symbol */ + unsigned int offset; + /* Called before addr is executed. */ kprobe_pre_handler_t pre_handler; diff -puN kernel/kallsyms.c~kprobes-make-kprobe-modules-more-portable kernel/kallsyms.c --- a/kernel/kallsyms.c~kprobes-make-kprobe-modules-more-portable +++ a/kernel/kallsyms.c @@ -154,7 +154,6 @@ unsigned long kallsyms_lookup_name(const } return module_kallsyms_lookup_name(name); } -EXPORT_SYMBOL_GPL(kallsyms_lookup_name); /* * Lookup an address diff -puN kernel/kprobes.c~kprobes-make-kprobe-modules-more-portable kernel/kprobes.c --- a/kernel/kprobes.c~kprobes-make-kprobe-modules-more-portable +++ a/kernel/kprobes.c @@ -37,6 +37,7 @@ #include #include #include +#include #include #include #include @@ -45,6 +46,16 @@ #define KPROBE_HASH_BITS 6 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) + +/* + * Some oddball architectures like 64bit powerpc have function descriptors + * so this must be overridable. + */ +#ifndef kprobe_lookup_name +#define kprobe_lookup_name(name) \ + ((kprobe_opcode_t *)(kallsyms_lookup_name(name))) +#endif + static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE]; static atomic_t kprobe_count; @@ -447,6 +458,21 @@ static int __kprobes __register_kprobe(s struct kprobe *old_p; struct module *probed_mod; + /* + * If we have a symbol_name argument look it up, + * and add it to the address. That way the addr + * field can either be global or relative to a symbol. + */ + if (p->symbol_name) { + if (p->addr) + return -EINVAL; + p->addr = kprobe_lookup_name(p->symbol_name); + } + + if (!p->addr) + return -EINVAL; + p->addr = (kprobe_opcode_t *)(((char *)p->addr)+ p->offset); + if ((!kernel_text_address((unsigned long) p->addr)) || in_kprobes_functions((unsigned long) p->addr)) return -EINVAL; diff -puN net/ipv4/tcp_probe.c~kprobes-make-kprobe-modules-more-portable net/ipv4/tcp_probe.c --- a/net/ipv4/tcp_probe.c~kprobes-make-kprobe-modules-more-portable +++ a/net/ipv4/tcp_probe.c @@ -99,8 +99,10 @@ static int jtcp_sendmsg(struct kiocb *io } static struct jprobe tcp_send_probe = { - .kp = { .addr = (kprobe_opcode_t *) &tcp_sendmsg, }, - .entry = (kprobe_opcode_t *) &jtcp_sendmsg, + .kp = { + .symbol_name = "tcp_sendmsg", + }, + .entry = JPROBE_ENTRY(jtcp_sendmsg), }; _