From: Ananth N Mavinakayanahalli Date: Mon, 2 Oct 2006 09:17:30 +0000 (-0700) Subject: [PATCH] Kprobes: Make kprobe modules more portable X-Git-Tag: v2.6.19-rc1~460 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3a872d89baae821a0f6e2c1055d4b47650661137;p=linux-2.6 [PATCH] Kprobes: Make kprobe modules more portable 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 Signed-off-by: Linus Torvalds --- diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig index 3fd2f256f2..af219e5173 100644 --- a/arch/i386/Kconfig +++ b/arch/i386/Kconfig @@ -1142,7 +1142,7 @@ 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 --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig index 0b7f701d5c..70f7eb9fed 100644 --- a/arch/ia64/Kconfig +++ b/arch/ia64/Kconfig @@ -516,7 +516,7 @@ 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 --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index a0dd1b0ee4..032e6ab5d3 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -1069,7 +1069,7 @@ 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 --git a/arch/sparc64/Kconfig b/arch/sparc64/Kconfig index 8d8ca716f7..b627f8dbca 100644 --- a/arch/sparc64/Kconfig +++ b/arch/sparc64/Kconfig @@ -420,7 +420,7 @@ 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 --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig index b87a19f0d5..0a5d8e659a 100644 --- a/arch/x86_64/Kconfig +++ b/arch/x86_64/Kconfig @@ -690,7 +690,7 @@ 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 --git a/include/asm-powerpc/kprobes.h b/include/asm-powerpc/kprobes.h index 34e1f89a5f..1ef54be6ab 100644 --- a/include/asm-powerpc/kprobes.h +++ b/include/asm-powerpc/kprobes.h @@ -44,6 +44,21 @@ typedef unsigned int kprobe_opcode_t; #define IS_TDI(instr) (((instr) & 0xfc000000) == 0x08000000) #define IS_TWI(instr) (((instr) & 0xfc000000) == 0x0c000000) +/* + * 64bit powerpc uses function descriptors. + * Handle cases where: + * - User passes a <.symbol> + * - User passes a + * - User passes a non-existant symbol, kallsyms_lookup_name + * returns 0. Don't deref the NULL pointer in that case + */ +#define kprobe_lookup_name(name, addr) \ +{ \ + addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); \ + if (!(name[0] == '.') && addr) \ + addr = *(kprobe_opcode_t **)addr; \ +} + #define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)((func_descr_t *)pentry) #define is_trap(instr) (IS_TW(instr) || IS_TD(instr) || \ diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 8bf6702da2..a5c5a0cb0d 100644 --- a/include/linux/kprobes.h +++ b/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 --git a/kernel/kallsyms.c b/kernel/kallsyms.c index ab16a5a4cf..342bca62c4 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -154,7 +154,6 @@ unsigned long kallsyms_lookup_name(const char *name) } return module_kallsyms_lookup_name(name); } -EXPORT_SYMBOL_GPL(kallsyms_lookup_name); /* * Lookup an address diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 3f57dfdc8f..f66b8e681b 100644 --- a/kernel/kprobes.c +++ b/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, addr) \ + addr = ((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(struct kprobe *p, 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; + kprobe_lookup_name(p->symbol_name, p->addr); + } + + 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 --git a/net/ipv4/tcp_probe.c b/net/ipv4/tcp_probe.c index dab37d2f65..4be336f178 100644 --- a/net/ipv4/tcp_probe.c +++ b/net/ipv4/tcp_probe.c @@ -99,8 +99,10 @@ static int jtcp_sendmsg(struct kiocb *iocb, struct sock *sk, } 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), };