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mirror_ubuntu-kernels/include/linux/uprobes.h
Jiri Olsa ff474a78ce uprobe: Add uretprobe syscall to speed up return probe 
Adding uretprobe syscall instead of trap to speed up return probe.

At the moment the uretprobe setup/path is:

  - install entry uprobe

  - when the uprobe is hit, it overwrites probed function's return address
    on stack with address of the trampoline that contains breakpoint
    instruction

  - the breakpoint trap code handles the uretprobe consumers execution and
    jumps back to original return address

This patch replaces the above trampoline's breakpoint instruction with new
ureprobe syscall call. This syscall does exactly the same job as the trap
with some more extra work:

  - syscall trampoline must save original value for rax/r11/rcx registers
    on stack - rax is set to syscall number and r11/rcx are changed and
    used by syscall instruction

  - the syscall code reads the original values of those registers and
    restore those values in task's pt_regs area

  - only caller from trampoline exposed in '[uprobes]' is allowed,
    the process will receive SIGILL signal otherwise

Even with some extra work, using the uretprobes syscall shows speed
improvement (compared to using standard breakpoint):

  On Intel (11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz)

  current:
    uretprobe-nop  :    1.498 ± 0.000M/s
    uretprobe-push :    1.448 ± 0.001M/s
    uretprobe-ret  :    0.816 ± 0.001M/s

  with the fix:
    uretprobe-nop  :    1.969 ± 0.002M/s  < 31% speed up
    uretprobe-push :    1.910 ± 0.000M/s  < 31% speed up
    uretprobe-ret  :    0.934 ± 0.000M/s  < 14% speed up

  On Amd (AMD Ryzen 7 5700U)

  current:
    uretprobe-nop  :    0.778 ± 0.001M/s
    uretprobe-push :    0.744 ± 0.001M/s
    uretprobe-ret  :    0.540 ± 0.001M/s

  with the fix:
    uretprobe-nop  :    0.860 ± 0.001M/s  < 10% speed up
    uretprobe-push :    0.818 ± 0.001M/s  < 10% speed up
    uretprobe-ret  :    0.578 ± 0.000M/s  <  7% speed up

The performance test spawns a thread that runs loop which triggers
uprobe with attached bpf program that increments the counter that
gets printed in results above.

The uprobe (and uretprobe) kind is determined by which instruction
is being patched with breakpoint instruction. That's also important
for uretprobes, because uprobe is installed for each uretprobe.

The performance test is part of bpf selftests:
  tools/testing/selftests/bpf/run_bench_uprobes.sh

Note at the moment uretprobe syscall is supported only for native
64-bit process, compat process still uses standard breakpoint.

Note that when shadow stack is enabled the uretprobe syscall returns
via iret, which is slower than return via sysret, but won't cause the
shadow stack violation.

Link: https://lore.kernel.org/all/20240611112158.40795-4-jolsa@kernel.org/

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2024-06-12 08:44:28 +09:00

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/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef _LINUX_UPROBES_H
#define _LINUX_UPROBES_H
/*
* User-space Probes (UProbes)
*
* Copyright (C) IBM Corporation, 2008-2012
* Authors:
* Srikar Dronamraju
* Jim Keniston
* Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra
*/
#include <linux/errno.h>
#include <linux/rbtree.h>
#include <linux/types.h>
#include <linux/wait.h>
struct vm_area_struct;
struct mm_struct;
struct inode;
struct notifier_block;
struct page;
#define UPROBE_HANDLER_REMOVE 1
#define UPROBE_HANDLER_MASK 1
#define MAX_URETPROBE_DEPTH 64
enum uprobe_filter_ctx {
UPROBE_FILTER_REGISTER,
UPROBE_FILTER_UNREGISTER,
UPROBE_FILTER_MMAP,
};
struct uprobe_consumer {
int (*handler)(struct uprobe_consumer *self, struct pt_regs *regs);
int (*ret_handler)(struct uprobe_consumer *self,
unsigned long func,
struct pt_regs *regs);
bool (*filter)(struct uprobe_consumer *self,
enum uprobe_filter_ctx ctx,
struct mm_struct *mm);
struct uprobe_consumer *next;
};
#ifdef CONFIG_UPROBES
#include <asm/uprobes.h>
enum uprobe_task_state {
UTASK_RUNNING,
UTASK_SSTEP,
UTASK_SSTEP_ACK,
UTASK_SSTEP_TRAPPED,
};
/*
* uprobe_task: Metadata of a task while it singlesteps.
*/
struct uprobe_task {
enum uprobe_task_state state;
union {
struct {
struct arch_uprobe_task autask;
unsigned long vaddr;
};
struct {
struct callback_head dup_xol_work;
unsigned long dup_xol_addr;
};
};
struct uprobe *active_uprobe;
unsigned long xol_vaddr;
struct return_instance *return_instances;
unsigned int depth;
};
struct return_instance {
struct uprobe *uprobe;
unsigned long func;
unsigned long stack; /* stack pointer */
unsigned long orig_ret_vaddr; /* original return address */
bool chained; /* true, if instance is nested */
struct return_instance *next; /* keep as stack */
};
enum rp_check {
RP_CHECK_CALL,
RP_CHECK_CHAIN_CALL,
RP_CHECK_RET,
};
struct xol_area;
struct uprobes_state {
struct xol_area *xol_area;
};
extern void __init uprobes_init(void);
extern int set_swbp(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr);
extern int set_orig_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long vaddr);
extern bool is_swbp_insn(uprobe_opcode_t *insn);
extern bool is_trap_insn(uprobe_opcode_t *insn);
extern unsigned long uprobe_get_swbp_addr(struct pt_regs *regs);
extern unsigned long uprobe_get_trap_addr(struct pt_regs *regs);
extern int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t);
extern int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc);
extern int uprobe_register_refctr(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc);
extern int uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool);
extern void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc);
extern int uprobe_mmap(struct vm_area_struct *vma);
extern void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end);
extern void uprobe_start_dup_mmap(void);
extern void uprobe_end_dup_mmap(void);
extern void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm);
extern void uprobe_free_utask(struct task_struct *t);
extern void uprobe_copy_process(struct task_struct *t, unsigned long flags);
extern int uprobe_post_sstep_notifier(struct pt_regs *regs);
extern int uprobe_pre_sstep_notifier(struct pt_regs *regs);
extern void uprobe_notify_resume(struct pt_regs *regs);
extern bool uprobe_deny_signal(void);
extern bool arch_uprobe_skip_sstep(struct arch_uprobe *aup, struct pt_regs *regs);
extern void uprobe_clear_state(struct mm_struct *mm);
extern int arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm, unsigned long addr);
extern int arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs);
extern int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs);
extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk);
extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data);
extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs);
extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs);
extern bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, struct pt_regs *regs);
extern bool arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs);
extern void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
void *src, unsigned long len);
extern void uprobe_handle_trampoline(struct pt_regs *regs);
extern void *arch_uprobe_trampoline(unsigned long *psize);
extern unsigned long uprobe_get_trampoline_vaddr(void);
#else /* !CONFIG_UPROBES */
struct uprobes_state {
};
static inline void uprobes_init(void)
{
}
#define uprobe_get_trap_addr(regs) instruction_pointer(regs)
static inline int
uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
{
return -ENOSYS;
}
static inline int uprobe_register_refctr(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc)
{
return -ENOSYS;
}
static inline int
uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool add)
{
return -ENOSYS;
}
static inline void
uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
{
}
static inline int uprobe_mmap(struct vm_area_struct *vma)
{
return 0;
}
static inline void
uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
{
}
static inline void uprobe_start_dup_mmap(void)
{
}
static inline void uprobe_end_dup_mmap(void)
{
}
static inline void
uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm)
{
}
static inline void uprobe_notify_resume(struct pt_regs *regs)
{
}
static inline bool uprobe_deny_signal(void)
{
return false;
}
static inline void uprobe_free_utask(struct task_struct *t)
{
}
static inline void uprobe_copy_process(struct task_struct *t, unsigned long flags)
{
}
static inline void uprobe_clear_state(struct mm_struct *mm)
{
}
#endif /* !CONFIG_UPROBES */
#endif /* _LINUX_UPROBES_H */
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