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rethook: x86: Add rethook x86 implementation
Add rethook for x86 implementation. Most of the code has been copied from kretprobes on x86. Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Tested-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/164735286243.1084943.7477055110527046644.stgit@devnote2
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5 changed files with 129 additions and 1 deletions
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@ -221,6 +221,7 @@ config X86
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select HAVE_KPROBES_ON_FTRACE
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select HAVE_FUNCTION_ERROR_INJECTION
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select HAVE_KRETPROBES
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select HAVE_RETHOOK
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select HAVE_KVM
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select HAVE_LIVEPATCH if X86_64
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select HAVE_MIXED_BREAKPOINTS_REGS
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@ -5,6 +5,7 @@
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#include <linux/sched.h>
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#include <linux/ftrace.h>
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#include <linux/kprobes.h>
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#include <linux/rethook.h>
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#include <asm/ptrace.h>
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#include <asm/stacktrace.h>
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@ -16,7 +17,7 @@ struct unwind_state {
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unsigned long stack_mask;
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struct task_struct *task;
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int graph_idx;
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#ifdef CONFIG_KRETPROBES
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#if defined(CONFIG_KRETPROBES) || defined(CONFIG_RETHOOK)
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struct llist_node *kr_cur;
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#endif
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bool error;
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@ -107,6 +108,11 @@ static inline
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unsigned long unwind_recover_kretprobe(struct unwind_state *state,
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unsigned long addr, unsigned long *addr_p)
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{
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#ifdef CONFIG_RETHOOK
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if (is_rethook_trampoline(addr))
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return rethook_find_ret_addr(state->task, (unsigned long)addr_p,
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&state->kr_cur);
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#endif
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#ifdef CONFIG_KRETPROBES
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return is_kretprobe_trampoline(addr) ?
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kretprobe_find_ret_addr(state->task, addr_p, &state->kr_cur) :
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@ -106,6 +106,7 @@ obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
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obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o
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obj-$(CONFIG_X86_TSC) += trace_clock.o
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obj-$(CONFIG_TRACING) += trace.o
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obj-$(CONFIG_RETHOOK) += rethook.o
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obj-$(CONFIG_CRASH_CORE) += crash_core_$(BITS).o
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obj-$(CONFIG_KEXEC_CORE) += machine_kexec_$(BITS).o
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obj-$(CONFIG_KEXEC_CORE) += relocate_kernel_$(BITS).o crash.o
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@ -6,6 +6,7 @@
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#include <asm/asm.h>
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#include <asm/frame.h>
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#include <asm/insn.h>
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#ifdef CONFIG_X86_64
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119
arch/x86/kernel/rethook.c
Normal file
119
arch/x86/kernel/rethook.c
Normal file
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@ -0,0 +1,119 @@
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* x86 implementation of rethook. Mostly copied from arch/x86/kernel/kprobes/core.c.
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*/
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#include <linux/bug.h>
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#include <linux/rethook.h>
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#include <linux/kprobes.h>
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#include "kprobes/common.h"
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__visible void arch_rethook_trampoline_callback(struct pt_regs *regs);
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/*
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* When a target function returns, this code saves registers and calls
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* arch_rethook_trampoline_callback(), which calls the rethook handler.
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*/
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asm(
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".text\n"
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".global arch_rethook_trampoline\n"
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".type arch_rethook_trampoline, @function\n"
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"arch_rethook_trampoline:\n"
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#ifdef CONFIG_X86_64
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/* Push a fake return address to tell the unwinder it's a kretprobe. */
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" pushq $arch_rethook_trampoline\n"
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UNWIND_HINT_FUNC
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/* Save the 'sp - 8', this will be fixed later. */
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" pushq %rsp\n"
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" pushfq\n"
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SAVE_REGS_STRING
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" movq %rsp, %rdi\n"
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" call arch_rethook_trampoline_callback\n"
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RESTORE_REGS_STRING
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/* In the callback function, 'regs->flags' is copied to 'regs->sp'. */
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" addq $8, %rsp\n"
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" popfq\n"
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#else
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/* Push a fake return address to tell the unwinder it's a kretprobe. */
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" pushl $arch_rethook_trampoline\n"
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UNWIND_HINT_FUNC
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/* Save the 'sp - 4', this will be fixed later. */
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" pushl %esp\n"
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" pushfl\n"
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SAVE_REGS_STRING
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" movl %esp, %eax\n"
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" call arch_rethook_trampoline_callback\n"
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RESTORE_REGS_STRING
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/* In the callback function, 'regs->flags' is copied to 'regs->sp'. */
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" addl $4, %esp\n"
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" popfl\n"
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#endif
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" ret\n"
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".size arch_rethook_trampoline, .-arch_rethook_trampoline\n"
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);
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NOKPROBE_SYMBOL(arch_rethook_trampoline);
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/*
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* Called from arch_rethook_trampoline
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*/
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__used __visible void arch_rethook_trampoline_callback(struct pt_regs *regs)
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{
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unsigned long *frame_pointer;
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/* fixup registers */
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regs->cs = __KERNEL_CS;
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#ifdef CONFIG_X86_32
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regs->gs = 0;
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#endif
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regs->ip = (unsigned long)&arch_rethook_trampoline;
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regs->orig_ax = ~0UL;
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regs->sp += sizeof(long);
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frame_pointer = ®s->sp + 1;
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/*
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* The return address at 'frame_pointer' is recovered by the
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* arch_rethook_fixup_return() which called from this
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* rethook_trampoline_handler().
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*/
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rethook_trampoline_handler(regs, (unsigned long)frame_pointer);
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/*
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* Copy FLAGS to 'pt_regs::sp' so that arch_rethook_trapmoline()
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* can do RET right after POPF.
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*/
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regs->sp = regs->flags;
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}
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NOKPROBE_SYMBOL(arch_rethook_trampoline_callback);
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/*
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* arch_rethook_trampoline() skips updating frame pointer. The frame pointer
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* saved in arch_rethook_trampoline_callback() points to the real caller
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* function's frame pointer. Thus the arch_rethook_trampoline() doesn't have
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* a standard stack frame with CONFIG_FRAME_POINTER=y.
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* Let's mark it non-standard function. Anyway, FP unwinder can correctly
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* unwind without the hint.
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*/
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STACK_FRAME_NON_STANDARD_FP(arch_rethook_trampoline);
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/* This is called from rethook_trampoline_handler(). */
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void arch_rethook_fixup_return(struct pt_regs *regs,
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unsigned long correct_ret_addr)
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{
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unsigned long *frame_pointer = ®s->sp + 1;
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/* Replace fake return address with real one. */
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*frame_pointer = correct_ret_addr;
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}
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NOKPROBE_SYMBOL(arch_rethook_fixup_return);
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void arch_rethook_prepare(struct rethook_node *rh, struct pt_regs *regs, bool mcount)
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{
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unsigned long *stack = (unsigned long *)regs->sp;
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rh->ret_addr = stack[0];
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rh->frame = regs->sp;
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/* Replace the return addr with trampoline addr */
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stack[0] = (unsigned long) arch_rethook_trampoline;
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}
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NOKPROBE_SYMBOL(arch_rethook_prepare);
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