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x86,rethook,kprobes: Replace kretprobe with rethook on x86

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Replaces the kretprobe code with rethook on x86. With this patch,
kretprobe on x86 uses the rethook instead of kretprobe specific
trampoline code.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/164826163692.2455864.13745421016848209527.stgit@devnote2
This commit is contained in:
Masami Hiramatsu 2022-03-26 11:27:17 +09:00 committed by Alexei Starovoitov
parent 73f9b911fa
commit f3a112c0c4
7 changed files with 144 additions and 124 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

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();

125
arch/x86/kernel/rethook.c Normal file
View File

@ -0,0 +1,125 @@
// 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
/* Save the 'sp - 8', 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->sp'. */
" addq $8, %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
/* Save the 'sp - 4', 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->sp'. */
" addl $4, %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 += sizeof(long);
frame_pointer = &regs->sp + 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::sp' so that arch_rethook_trapmoline()
* can do RET right after POPF.
*/
regs->sp = 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 = &regs->sp + 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)