iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Merge branch 'kprobes: rethook: x86: Replace kretprobe trampoline with rethook'

Browse Source 
Masami Hiramatsu says:

====================
Here are the 3rd version for generic kretprobe and kretprobe on x86 for
replacing the kretprobe trampoline with rethook. The previous version
is here[1]

[1] https://lore.kernel.org/all/164821817332.2373735.12048266953420821089.stgit@devnote2/T/#u

This version fixed typo and build issues for bpf-next and CONFIG_RETHOOK=y
error. I also add temporary mitigation lines for ANNOTATE_NOENDBR macro
issue for bpf-next tree [2/4].

This will be removed after merging kernel IBT series.

Background:

This rethook came from Jiri's request of multiple kprobe for bpf[2].
He tried to solve an issue that starting bpf with multiple kprobe will
take a long time because bpf-kprobe will wait for RCU grace period for
sync rcu events.

Jiri wanted to attach a single bpf handler to multiple kprobes and
he tried to introduce multiple-probe interface to kprobe. So I asked
him to use ftrace and kretprobe-like hook if it is only for the
function entry and exit, instead of adding ad-hoc interface
to kprobes.
For this purpose, I introduced the fprobe (kprobe like interface for
ftrace) with the rethook (this is a generic return hook feature for
fprobe exit handler)[3].

[2] https://lore.kernel.org/all/20220104080943.113249-1-jolsa@kernel.org/T/#u
[3] https://lore.kernel.org/all/164191321766.806991.7930388561276940676.stgit@devnote2/T/#u

The rethook is basically same as the kretprobe trampoline. I just made
it decoupled from kprobes. Eventually, the all arch dependent kretprobe
trampolines will be replaced with the rethook trampoline instead of
cloning and set HAVE_RETHOOK=y.
When I port the rethook for all arch which supports kretprobe, the
legacy kretprobe specific code (which is for CONFIG_KRETPROBE_ON_RETHOOK=n)
will be removed eventually.
====================

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2022-03-28 19:39:06 -07:00
commit 7df482e622
13 changed files with 325 additions and 158 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/Kconfig
View File

@ -164,7 +164,13 @@ config ARCH_USE_BUILTIN_BSWAP
config KRETPROBES
def_bool y
depends on KPROBES && HAVE_KRETPROBES
depends on KPROBES && (HAVE_KRETPROBES || HAVE_RETHOOK)
config KRETPROBE_ON_RETHOOK
def_bool y
depends on HAVE_RETHOOK
depends on KRETPROBES
select RETHOOK
config USER_RETURN_NOTIFIER
bool

1
arch/x86/Kconfig
View File

@ -224,6 +224,7 @@ config X86
select HAVE_KPROBES_ON_FTRACE
select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_KRETPROBES
select HAVE_RETHOOK
select HAVE_KVM
select HAVE_LIVEPATCH if X86_64
select HAVE_MIXED_BREAKPOINTS_REGS

23
arch/x86/include/asm/unwind.h
View File

@ -4,7 +4,7 @@
#include <linux/sched.h>
#include <linux/ftrace.h>
#include <linux/kprobes.h>
#include <linux/rethook.h>
#include <asm/ptrace.h>
#include <asm/stacktrace.h>
@ -16,7 +16,7 @@ struct unwind_state {
unsigned long stack_mask;
struct task_struct *task;
int graph_idx;
#ifdef CONFIG_KRETPROBES
#if defined(CONFIG_RETHOOK)
struct llist_node *kr_cur;
#endif
bool error;
@ -104,19 +104,18 @@ void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size,
#endif
static inline
unsigned long unwind_recover_kretprobe(struct unwind_state *state,
unsigned long addr, unsigned long *addr_p)
unsigned long unwind_recover_rethook(struct unwind_state *state,
unsigned long addr, unsigned long *addr_p)
{
#ifdef CONFIG_KRETPROBES
return is_kretprobe_trampoline(addr) ?
kretprobe_find_ret_addr(state->task, addr_p, &state->kr_cur) :
addr;
#else
return addr;
#ifdef CONFIG_RETHOOK
if (is_rethook_trampoline(addr))
return rethook_find_ret_addr(state->task, (unsigned long)addr_p,
&state->kr_cur);
#endif
return addr;
}
/* Recover the return address modified by kretprobe and ftrace_graph. */
/* Recover the return address modified by rethook and ftrace_graph. */
static inline
unsigned long unwind_recover_ret_addr(struct unwind_state *state,
unsigned long addr, unsigned long *addr_p)
@ -125,7 +124,7 @@ unsigned long unwind_recover_ret_addr(struct unwind_state *state,
ret = ftrace_graph_ret_addr(state->task, &state->graph_idx,
addr, addr_p);
return unwind_recover_kretprobe(state, ret, addr_p);
return unwind_recover_rethook(state, ret, addr_p);
}
/*

1
arch/x86/kernel/Makefile
View File

@ -103,6 +103,7 @@ obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o
obj-$(CONFIG_X86_TSC) += trace_clock.o
obj-$(CONFIG_TRACING) += trace.o
obj-$(CONFIG_RETHOOK) += rethook.o
obj-$(CONFIG_CRASH_CORE) += crash_core_$(BITS).o
obj-$(CONFIG_KEXEC_CORE) += machine_kexec_$(BITS).o
obj-$(CONFIG_KEXEC_CORE) += relocate_kernel_$(BITS).o crash.o

1
arch/x86/kernel/kprobes/common.h
View File

@ -6,6 +6,7 @@
#include <asm/asm.h>
#include <asm/frame.h>
#include <asm/insn.h>
#ifdef CONFIG_X86_64

107
arch/x86/kernel/kprobes/core.c
View File

@ -811,18 +811,6 @@ set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
= (regs->flags & X86_EFLAGS_IF);
}
void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
{
unsigned long *sara = stack_addr(regs);
ri->ret_addr = (kprobe_opcode_t *) *sara;
ri->fp = sara;
/* Replace the return addr with trampoline addr */
*sara = (unsigned long) &__kretprobe_trampoline;
}
NOKPROBE_SYMBOL(arch_prepare_kretprobe);
static void kprobe_post_process(struct kprobe *cur, struct pt_regs *regs,
struct kprobe_ctlblk *kcb)
{
@ -1023,101 +1011,6 @@ int kprobe_int3_handler(struct pt_regs *regs)
}
NOKPROBE_SYMBOL(kprobe_int3_handler);
/*
* When a retprobed function returns, this code saves registers and
* calls trampoline_handler() runs, which calls the kretprobe's handler.
*/
asm(
".text\n"
".global __kretprobe_trampoline\n"
".type __kretprobe_trampoline, @function\n"
"__kretprobe_trampoline:\n"
#ifdef CONFIG_X86_64
ANNOTATE_NOENDBR
/* Push a fake return address to tell the unwinder it's a kretprobe. */
" pushq $__kretprobe_trampoline\n"
UNWIND_HINT_FUNC
/* Save the 'sp - 8', this will be fixed later. */
" pushq %rsp\n"
" pushfq\n"
SAVE_REGS_STRING
" movq %rsp, %rdi\n"
" call trampoline_handler\n"
RESTORE_REGS_STRING
/* In trampoline_handler(), 'regs->flags' is copied to 'regs->sp'. */
" addq $8, %rsp\n"
" popfq\n"
#else
/* Push a fake return address to tell the unwinder it's a kretprobe. */
" pushl $__kretprobe_trampoline\n"
UNWIND_HINT_FUNC
/* Save the 'sp - 4', this will be fixed later. */
" pushl %esp\n"
" pushfl\n"
SAVE_REGS_STRING
" movl %esp, %eax\n"
" call trampoline_handler\n"
RESTORE_REGS_STRING
/* In trampoline_handler(), 'regs->flags' is copied to 'regs->sp'. */
" addl $4, %esp\n"
" popfl\n"
#endif
ASM_RET
".size __kretprobe_trampoline, .-__kretprobe_trampoline\n"
);
NOKPROBE_SYMBOL(__kretprobe_trampoline);
/*
* __kretprobe_trampoline() skips updating frame pointer. The frame pointer
* saved in trampoline_handler() points to the real caller function's
* frame pointer. Thus the __kretprobe_trampoline() doesn't have a
* standard stack frame with CONFIG_FRAME_POINTER=y.
* Let's mark it non-standard function. Anyway, FP unwinder can correctly
* unwind without the hint.
*/
STACK_FRAME_NON_STANDARD_FP(__kretprobe_trampoline);
/* This is called from kretprobe_trampoline_handler(). */
void arch_kretprobe_fixup_return(struct pt_regs *regs,
kprobe_opcode_t *correct_ret_addr)
{
unsigned long *frame_pointer = &regs->sp + 1;
/* Replace fake return address with real one. */
*frame_pointer = (unsigned long)correct_ret_addr;
}
/*
* Called from __kretprobe_trampoline
*/
__used __visible void trampoline_handler(struct pt_regs *regs)
{
unsigned long *frame_pointer;
/* fixup registers */
regs->cs = __KERNEL_CS;
#ifdef CONFIG_X86_32
regs->gs = 0;
#endif
regs->ip = (unsigned long)&__kretprobe_trampoline;
regs->orig_ax = ~0UL;
regs->sp += sizeof(long);
frame_pointer = &regs->sp + 1;
/*
* The return address at 'frame_pointer' is recovered by the
* arch_kretprobe_fixup_return() which called from the
* kretprobe_trampoline_handler().
*/
kretprobe_trampoline_handler(regs, frame_pointer);
/*
* Copy FLAGS to 'pt_regs::sp' so that __kretprobe_trapmoline()
* can do RET right after POPF.
*/
regs->sp = regs->flags;
}
NOKPROBE_SYMBOL(trampoline_handler);
int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
struct kprobe *cur = kprobe_running();

25
arch/x86/kernel/kprobes/opt.c
View File

@ -106,7 +106,8 @@ asm (
".global optprobe_template_entry\n"
"optprobe_template_entry:\n"
#ifdef CONFIG_X86_64
/* We don't bother saving the ss register */
" pushq $" __stringify(__KERNEL_DS) "\n"
/* Save the 'sp - 8', this will be fixed later. */
" pushq %rsp\n"
" pushfq\n"
".global optprobe_template_clac\n"
@ -121,14 +122,17 @@ asm (
".global optprobe_template_call\n"
"optprobe_template_call:\n"
ASM_NOP5
/* Move flags to rsp */
/* Copy 'regs->flags' into 'regs->ss'. */
" movq 18*8(%rsp), %rdx\n"
" movq %rdx, 19*8(%rsp)\n"
" movq %rdx, 20*8(%rsp)\n"
RESTORE_REGS_STRING
/* Skip flags entry */
" addq $8, %rsp\n"
/* Skip 'regs->flags' and 'regs->sp'. */
" addq $16, %rsp\n"
/* And pop flags register from 'regs->ss'. */
" popfq\n"
#else /* CONFIG_X86_32 */
" pushl %ss\n"
/* Save the 'sp - 4', this will be fixed later. */
" pushl %esp\n"
" pushfl\n"
".global optprobe_template_clac\n"
@ -142,12 +146,13 @@ asm (
".global optprobe_template_call\n"
"optprobe_template_call:\n"
ASM_NOP5
/* Move flags into esp */
/* Copy 'regs->flags' into 'regs->ss'. */
" movl 14*4(%esp), %edx\n"
" movl %edx, 15*4(%esp)\n"
" movl %edx, 16*4(%esp)\n"
RESTORE_REGS_STRING
/* Skip flags entry */
" addl $4, %esp\n"
/* Skip 'regs->flags' and 'regs->sp'. */
" addl $8, %esp\n"
/* And pop flags register from 'regs->ss'. */
" popfl\n"
#endif
".global optprobe_template_end\n"
@ -179,6 +184,8 @@ optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
kprobes_inc_nmissed_count(&op->kp);
} else {
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
/* Adjust stack pointer */
regs->sp += sizeof(long);
/* Save skipped registers */
regs->cs = __KERNEL_CS;
#ifdef CONFIG_X86_32

127
arch/x86/kernel/rethook.c Normal file
View File

@ -0,0 +1,127 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* x86 implementation of rethook. Mostly copied from arch/x86/kernel/kprobes/core.c.
*/
#include <linux/bug.h>
#include <linux/rethook.h>
#include <linux/kprobes.h>
#include <linux/objtool.h>
#include "kprobes/common.h"
__visible void arch_rethook_trampoline_callback(struct pt_regs *regs);
#ifndef ANNOTATE_NOENDBR
#define ANNOTATE_NOENDBR
#endif
/*
* When a target function returns, this code saves registers and calls
* arch_rethook_trampoline_callback(), which calls the rethook handler.
*/
asm(
".text\n"
".global arch_rethook_trampoline\n"
".type arch_rethook_trampoline, @function\n"
"arch_rethook_trampoline:\n"
#ifdef CONFIG_X86_64
ANNOTATE_NOENDBR /* This is only jumped from ret instruction */
/* Push a fake return address to tell the unwinder it's a rethook. */
" pushq $arch_rethook_trampoline\n"
UNWIND_HINT_FUNC
" pushq $" __stringify(__KERNEL_DS) "\n"
/* Save the 'sp - 16', this will be fixed later. */
" pushq %rsp\n"
" pushfq\n"
SAVE_REGS_STRING
" movq %rsp, %rdi\n"
" call arch_rethook_trampoline_callback\n"
RESTORE_REGS_STRING
/* In the callback function, 'regs->flags' is copied to 'regs->ss'. */
" addq $16, %rsp\n"
" popfq\n"
#else
/* Push a fake return address to tell the unwinder it's a rethook. */
" pushl $arch_rethook_trampoline\n"
UNWIND_HINT_FUNC
" pushl %ss\n"
/* Save the 'sp - 8', this will be fixed later. */
" pushl %esp\n"
" pushfl\n"
SAVE_REGS_STRING
" movl %esp, %eax\n"
" call arch_rethook_trampoline_callback\n"
RESTORE_REGS_STRING
/* In the callback function, 'regs->flags' is copied to 'regs->ss'. */
" addl $8, %esp\n"
" popfl\n"
#endif
ASM_RET
".size arch_rethook_trampoline, .-arch_rethook_trampoline\n"
);
NOKPROBE_SYMBOL(arch_rethook_trampoline);
/*
* Called from arch_rethook_trampoline
*/
__used __visible void arch_rethook_trampoline_callback(struct pt_regs *regs)
{
unsigned long *frame_pointer;
/* fixup registers */
regs->cs = __KERNEL_CS;
#ifdef CONFIG_X86_32
regs->gs = 0;
#endif
regs->ip = (unsigned long)&arch_rethook_trampoline;
regs->orig_ax = ~0UL;
regs->sp += 2*sizeof(long);
frame_pointer = (long *)(regs + 1);
/*
* The return address at 'frame_pointer' is recovered by the
* arch_rethook_fixup_return() which called from this
* rethook_trampoline_handler().
*/
rethook_trampoline_handler(regs, (unsigned long)frame_pointer);
/*
* Copy FLAGS to 'pt_regs::ss' so that arch_rethook_trapmoline()
* can do RET right after POPF.
*/
*(unsigned long *)&regs->ss = regs->flags;
}
NOKPROBE_SYMBOL(arch_rethook_trampoline_callback);
/*
* arch_rethook_trampoline() skips updating frame pointer. The frame pointer
* saved in arch_rethook_trampoline_callback() points to the real caller
* function's frame pointer. Thus the arch_rethook_trampoline() doesn't have
* a standard stack frame with CONFIG_FRAME_POINTER=y.
* Let's mark it non-standard function. Anyway, FP unwinder can correctly
* unwind without the hint.
*/
STACK_FRAME_NON_STANDARD_FP(arch_rethook_trampoline);
/* This is called from rethook_trampoline_handler(). */
void arch_rethook_fixup_return(struct pt_regs *regs,
unsigned long correct_ret_addr)
{
unsigned long *frame_pointer = (void *)(regs + 1);
/* Replace fake return address with real one. */
*frame_pointer = correct_ret_addr;
}
NOKPROBE_SYMBOL(arch_rethook_fixup_return);
void arch_rethook_prepare(struct rethook_node *rh, struct pt_regs *regs, bool mcount)
{
unsigned long *stack = (unsigned long *)regs->sp;
rh->ret_addr = stack[0];
rh->frame = regs->sp;
/* Replace the return addr with trampoline addr */
stack[0] = (unsigned long) arch_rethook_trampoline;
}
NOKPROBE_SYMBOL(arch_rethook_prepare);

10
arch/x86/kernel/unwind_orc.c
View File

@ -550,15 +550,15 @@ bool unwind_next_frame(struct unwind_state *state)
}
/*
* There is a small chance to interrupt at the entry of
* __kretprobe_trampoline() where the ORC info doesn't exist.
* That point is right after the RET to __kretprobe_trampoline()
* arch_rethook_trampoline() where the ORC info doesn't exist.
* That point is right after the RET to arch_rethook_trampoline()
* which was modified return address.
* At that point, the @addr_p of the unwind_recover_kretprobe()
* At that point, the @addr_p of the unwind_recover_rethook()
* (this has to point the address of the stack entry storing
* the modified return address) must be "SP - (a stack entry)"
* because SP is incremented by the RET.
*/
state->ip = unwind_recover_kretprobe(state, state->ip,
state->ip = unwind_recover_rethook(state, state->ip,
(unsigned long *)(state->sp - sizeof(long)));
state->regs = (struct pt_regs *)sp;
state->prev_regs = NULL;
@ -573,7 +573,7 @@ bool unwind_next_frame(struct unwind_state *state)
goto err;
}
/* See UNWIND_HINT_TYPE_REGS case comment. */
state->ip = unwind_recover_kretprobe(state, state->ip,
state->ip = unwind_recover_rethook(state, state->ip,
(unsigned long *)(state->sp - sizeof(long)));
if (state->full_regs)

51
include/linux/kprobes.h
View File

@ -28,6 +28,7 @@
#include <linux/ftrace.h>
#include <linux/refcount.h>
#include <linux/freelist.h>
#include <linux/rethook.h>
#include <asm/kprobes.h>
#ifdef CONFIG_KPROBES
@ -149,13 +150,20 @@ struct kretprobe {
int maxactive;
int nmissed;
size_t data_size;
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
struct rethook *rh;
#else
struct freelist_head freelist;
struct kretprobe_holder *rph;
#endif
};
#define KRETPROBE_MAX_DATA_SIZE 4096
struct kretprobe_instance {
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
struct rethook_node node;
#else
union {
struct freelist_node freelist;
struct rcu_head rcu;
@ -164,6 +172,7 @@ struct kretprobe_instance {
struct kretprobe_holder *rph;
kprobe_opcode_t *ret_addr;
void *fp;
#endif
char data[];
};
@ -186,10 +195,24 @@ extern void kprobe_busy_begin(void);
extern void kprobe_busy_end(void);
#ifdef CONFIG_KRETPROBES
extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs);
/* Check whether @p is used for implementing a trampoline. */
extern int arch_trampoline_kprobe(struct kprobe *p);
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance *ri)
{
RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
"Kretprobe is accessed from instance under preemptive context");
return (struct kretprobe *)READ_ONCE(ri->node.rethook->data);
}
static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri)
{
return ri->node.ret_addr;
}
#else
extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs);
void arch_kretprobe_fixup_return(struct pt_regs *regs,
kprobe_opcode_t *correct_ret_addr);
@ -232,6 +255,12 @@ static nokprobe_inline struct kretprobe *get_kretprobe(struct kretprobe_instance
return READ_ONCE(ri->rph->rp);
}
static nokprobe_inline unsigned long get_kretprobe_retaddr(struct kretprobe_instance *ri)
{
return (unsigned long)ri->ret_addr;
}
#endif /* CONFIG_KRETPROBE_ON_RETHOOK */
#else /* !CONFIG_KRETPROBES */
static inline void arch_prepare_kretprobe(struct kretprobe *rp,
struct pt_regs *regs)
@ -395,7 +424,11 @@ void unregister_kretprobe(struct kretprobe *rp);
int register_kretprobes(struct kretprobe **rps, int num);
void unregister_kretprobes(struct kretprobe **rps, int num);
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
#define kprobe_flush_task(tk) do {} while (0)
#else
void kprobe_flush_task(struct task_struct *tk);
#endif
void kprobe_free_init_mem(void);
@ -509,6 +542,19 @@ static inline bool is_kprobe_optinsn_slot(unsigned long addr)
#endif /* !CONFIG_OPTPROBES */
#ifdef CONFIG_KRETPROBES
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
{
return is_rethook_trampoline(addr);
}
static nokprobe_inline
unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
struct llist_node **cur)
{
return rethook_find_ret_addr(tsk, (unsigned long)fp, cur);
}
#else
static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
{
return (void *)addr == kretprobe_trampoline_addr();
@ -516,6 +562,7 @@ static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
struct llist_node **cur);
#endif
#else
static nokprobe_inline bool is_kretprobe_trampoline(unsigned long addr)
{

1
kernel/Makefile
View File

@ -108,6 +108,7 @@ obj-$(CONFIG_TRACING) += trace/
obj-$(CONFIG_TRACE_CLOCK) += trace/
obj-$(CONFIG_RING_BUFFER) += trace/
obj-$(CONFIG_TRACEPOINTS) += trace/
obj-$(CONFIG_RETHOOK) += trace/
obj-$(CONFIG_IRQ_WORK) += irq_work.o
obj-$(CONFIG_CPU_PM) += cpu_pm.o
obj-$(CONFIG_BPF) += bpf/

124
kernel/kprobes.c
View File

@ -1237,6 +1237,27 @@ void kprobes_inc_nmissed_count(struct kprobe *p)
}
NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
static struct kprobe kprobe_busy = {
.addr = (void *) get_kprobe,
};
void kprobe_busy_begin(void)
{
struct kprobe_ctlblk *kcb;
preempt_disable();
__this_cpu_write(current_kprobe, &kprobe_busy);
kcb = get_kprobe_ctlblk();
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
}
void kprobe_busy_end(void)
{
__this_cpu_write(current_kprobe, NULL);
preempt_enable();
}
#if !defined(CONFIG_KRETPROBE_ON_RETHOOK)
static void free_rp_inst_rcu(struct rcu_head *head)
{
struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu);
@ -1258,26 +1279,6 @@ static void recycle_rp_inst(struct kretprobe_instance *ri)
}
NOKPROBE_SYMBOL(recycle_rp_inst);
static struct kprobe kprobe_busy = {
.addr = (void *) get_kprobe,
};
void kprobe_busy_begin(void)
{
struct kprobe_ctlblk *kcb;
preempt_disable();
__this_cpu_write(current_kprobe, &kprobe_busy);
kcb = get_kprobe_ctlblk();
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
}
void kprobe_busy_end(void)
{
__this_cpu_write(current_kprobe, NULL);
preempt_enable();
}
/*
* This function is called from delayed_put_task_struct() when a task is
* dead and cleaned up to recycle any kretprobe instances associated with
@ -1327,6 +1328,7 @@ static inline void free_rp_inst(struct kretprobe *rp)
rp->rph = NULL;
}
}
#endif /* !CONFIG_KRETPROBE_ON_RETHOOK */
/* Add the new probe to 'ap->list'. */
static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
@ -1925,6 +1927,7 @@ static struct notifier_block kprobe_exceptions_nb = {
#ifdef CONFIG_KRETPROBES
#if !defined(CONFIG_KRETPROBE_ON_RETHOOK)
/* This assumes the 'tsk' is the current task or the is not running. */
static kprobe_opcode_t *__kretprobe_find_ret_addr(struct task_struct *tsk,
struct llist_node **cur)
@ -2087,6 +2090,57 @@ static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
return 0;
}
NOKPROBE_SYMBOL(pre_handler_kretprobe);
#else /* CONFIG_KRETPROBE_ON_RETHOOK */
/*
* This kprobe pre_handler is registered with every kretprobe. When probe
* hits it will set up the return probe.
*/
static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
{
struct kretprobe *rp = container_of(p, struct kretprobe, kp);
struct kretprobe_instance *ri;
struct rethook_node *rhn;
rhn = rethook_try_get(rp->rh);
if (!rhn) {
rp->nmissed++;
return 0;
}
ri = container_of(rhn, struct kretprobe_instance, node);
if (rp->entry_handler && rp->entry_handler(ri, regs))
rethook_recycle(rhn);
else
rethook_hook(rhn, regs, kprobe_ftrace(p));
return 0;
}
NOKPROBE_SYMBOL(pre_handler_kretprobe);
static void kretprobe_rethook_handler(struct rethook_node *rh, void *data,
struct pt_regs *regs)
{
struct kretprobe *rp = (struct kretprobe *)data;
struct kretprobe_instance *ri;
struct kprobe_ctlblk *kcb;
/* The data must NOT be null. This means rethook data structure is broken. */
if (WARN_ON_ONCE(!data))
return;
__this_cpu_write(current_kprobe, &rp->kp);
kcb = get_kprobe_ctlblk();
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
ri = container_of(rh, struct kretprobe_instance, node);
rp->handler(ri, regs);
__this_cpu_write(current_kprobe, NULL);
}
NOKPROBE_SYMBOL(kretprobe_rethook_handler);
#endif /* !CONFIG_KRETPROBE_ON_RETHOOK */
/**
* kprobe_on_func_entry() -- check whether given address is function entry
@ -2155,6 +2209,29 @@ int register_kretprobe(struct kretprobe *rp)
rp->maxactive = num_possible_cpus();
#endif
}
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
rp->rh = rethook_alloc((void *)rp, kretprobe_rethook_handler);
if (!rp->rh)
return -ENOMEM;
for (i = 0; i < rp->maxactive; i++) {
inst = kzalloc(sizeof(struct kretprobe_instance) +
rp->data_size, GFP_KERNEL);
if (inst == NULL) {
rethook_free(rp->rh);
rp->rh = NULL;
return -ENOMEM;
}
rethook_add_node(rp->rh, &inst->node);
}
rp->nmissed = 0;
/* Establish function entry probe point */
ret = register_kprobe(&rp->kp);
if (ret != 0) {
rethook_free(rp->rh);
rp->rh = NULL;
}
#else /* !CONFIG_KRETPROBE_ON_RETHOOK */
rp->freelist.head = NULL;
rp->rph = kzalloc(sizeof(struct kretprobe_holder), GFP_KERNEL);
if (!rp->rph)
@ -2179,6 +2256,7 @@ int register_kretprobe(struct kretprobe *rp)
ret = register_kprobe(&rp->kp);
if (ret != 0)
free_rp_inst(rp);
#endif
return ret;
}
EXPORT_SYMBOL_GPL(register_kretprobe);
@ -2217,7 +2295,11 @@ void unregister_kretprobes(struct kretprobe **rps, int num)
for (i = 0; i < num; i++) {
if (__unregister_kprobe_top(&rps[i]->kp) < 0)
rps[i]->kp.addr = NULL;
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
rethook_free(rps[i]->rh);
#else
rps[i]->rph->rp = NULL;
#endif
}
mutex_unlock(&kprobe_mutex);
@ -2225,7 +2307,9 @@ void unregister_kretprobes(struct kretprobe **rps, int num)
for (i = 0; i < num; i++) {
if (rps[i]->kp.addr) {
__unregister_kprobe_bottom(&rps[i]->kp);
#ifndef CONFIG_KRETPROBE_ON_RETHOOK
free_rp_inst(rps[i]);
#endif
}
}
}

4
kernel/trace/trace_kprobe.c
View File

@ -1433,7 +1433,7 @@ __kretprobe_trace_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
fbuffer.regs = regs;
entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
entry->func = (unsigned long)tk->rp.kp.addr;
entry->ret_ip = (unsigned long)ri->ret_addr;
entry->ret_ip = get_kretprobe_retaddr(ri);
store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
trace_event_buffer_commit(&fbuffer);
@ -1628,7 +1628,7 @@ kretprobe_perf_func(struct trace_kprobe *tk, struct kretprobe_instance *ri,
return;
entry->func = (unsigned long)tk->rp.kp.addr;
entry->ret_ip = (unsigned long)ri->ret_addr;
entry->ret_ip = get_kretprobe_retaddr(ri);
store_trace_args(&entry[1], &tk->tp, regs, sizeof(*entry), dsize);
perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
head, NULL);