Revert "rethook: x86: Add rethook x86 implementation"

This reverts commit 75caf33e.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

arch/x86/Kconfig

@@ -221,7 +221,6 @@ 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

arch/x86/include/asm/unwind.h

@@ -5,7 +5,6 @@
 #include <linux/sched.h>
 #include <linux/ftrace.h>
 #include <linux/kprobes.h>
-#include <linux/rethook.h>
 #include <asm/ptrace.h>
 #include <asm/stacktrace.h>
 
@@ -17,7 +16,7 @@ struct unwind_state {
 	unsigned long stack_mask;
 	struct task_struct *task;
 	int graph_idx;
-#if defined(CONFIG_KRETPROBES) || defined(CONFIG_RETHOOK)
+#ifdef CONFIG_KRETPROBES
 	struct llist_node *kr_cur;
 #endif
 	bool error;
@@ -108,11 +107,6 @@ static inline
 unsigned long unwind_recover_kretprobe(struct unwind_state *state,
 				       unsigned long addr, unsigned long *addr_p)
 {
-#ifdef CONFIG_RETHOOK
-	if (is_rethook_trampoline(addr))
-		return rethook_find_ret_addr(state->task, (unsigned long)addr_p,
-					     &state->kr_cur);
-#endif
 #ifdef CONFIG_KRETPROBES
 	return is_kretprobe_trampoline(addr) ?
 		kretprobe_find_ret_addr(state->task, addr_p, &state->kr_cur) :

arch/x86/kernel/Makefile

@@ -106,7 +106,6 @@ 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

arch/x86/kernel/kprobes/common.h

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

arch/x86/kernel/rethook.c

-// 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 "kprobes/common.h"
-
-__visible void arch_rethook_trampoline_callback(struct pt_regs *regs);
-
-/*
- * 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
-	/* Push a fake return address to tell the unwinder it's a kretprobe. */
-	"	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 kretprobe. */
-	"	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
-	"	ret\n"
-	".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);