Revert "arm64: rethook: Add arm64 rethook implementation"

This reverts commit 83acdce6.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

arch/arm64/Kconfig

@@ -201,7 +201,6 @@ config ARM64
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
-	select HAVE_RETHOOK
 	select HAVE_GENERIC_VDSO
 	select IOMMU_DMA if IOMMU_SUPPORT
 	select IRQ_DOMAIN

arch/arm64/include/asm/stacktrace.h

@@ -58,7 +58,7 @@ struct stackframe {
 	DECLARE_BITMAP(stacks_done, __NR_STACK_TYPES);
 	unsigned long prev_fp;
 	enum stack_type prev_type;
-#if defined(CONFIG_KRETPROBES) || defined(CONFIG_RETHOOK)
+#ifdef CONFIG_KRETPROBES
 	struct llist_node *kr_cur;
 #endif
 };

arch/arm64/kernel/probes/Makefile

@@ -4,4 +4,3 @@ obj-$(CONFIG_KPROBES)		+= kprobes.o decode-insn.o	\
 				   simulate-insn.o
 obj-$(CONFIG_UPROBES)		+= uprobes.o decode-insn.o	\
 				   simulate-insn.o
-obj-$(CONFIG_RETHOOK)		+= rethook.o rethook_trampoline.o

arch/arm64/kernel/probes/rethook.c

-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Generic return hook for arm64.
- * Most of the code is copied from arch/arm64/kernel/probes/kprobes.c
- */
-
-#include <linux/kprobes.h>
-#include <linux/rethook.h>
-
-/* This is called from arch_rethook_trampoline() */
-unsigned long __used arch_rethook_trampoline_callback(struct pt_regs *regs)
-{
-	return rethook_trampoline_handler(regs, regs->regs[29]);
-}
-NOKPROBE_SYMBOL(arch_rethook_trampoline_callback);
-
-void arch_rethook_prepare(struct rethook_node *rhn, struct pt_regs *regs, bool mcount)
-{
-	rhn->ret_addr = regs->regs[30];
-	rhn->frame = regs->regs[29];
-
-	/* replace return addr (x30) with trampoline */
-	regs->regs[30] = (u64)arch_rethook_trampoline;
-}
-NOKPROBE_SYMBOL(arch_rethook_prepare);

arch/arm64/kernel/probes/rethook_trampoline.S

-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * trampoline entry and return code for rethook.
- * Copied from arch/arm64/kernel/probes/kprobes_trampoline.S
- */
-
-#include <linux/linkage.h>
-#include <asm/asm-offsets.h>
-#include <asm/assembler.h>
-
-	.text
-
-	.macro	save_all_base_regs
-	stp x0, x1, [sp, #S_X0]
-	stp x2, x3, [sp, #S_X2]
-	stp x4, x5, [sp, #S_X4]
-	stp x6, x7, [sp, #S_X6]
-	stp x8, x9, [sp, #S_X8]
-	stp x10, x11, [sp, #S_X10]
-	stp x12, x13, [sp, #S_X12]
-	stp x14, x15, [sp, #S_X14]
-	stp x16, x17, [sp, #S_X16]
-	stp x18, x19, [sp, #S_X18]
-	stp x20, x21, [sp, #S_X20]
-	stp x22, x23, [sp, #S_X22]
-	stp x24, x25, [sp, #S_X24]
-	stp x26, x27, [sp, #S_X26]
-	stp x28, x29, [sp, #S_X28]
-	add x0, sp, #PT_REGS_SIZE
-	stp lr, x0, [sp, #S_LR]
-	/*
-	 * Construct a useful saved PSTATE
-	 */
-	mrs x0, nzcv
-	mrs x1, daif
-	orr x0, x0, x1
-	mrs x1, CurrentEL
-	orr x0, x0, x1
-	mrs x1, SPSel
-	orr x0, x0, x1
-	stp xzr, x0, [sp, #S_PC]
-	.endm
-
-	.macro	restore_all_base_regs
-	ldr x0, [sp, #S_PSTATE]
-	and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT)
-	msr nzcv, x0
-	ldp x0, x1, [sp, #S_X0]
-	ldp x2, x3, [sp, #S_X2]
-	ldp x4, x5, [sp, #S_X4]
-	ldp x6, x7, [sp, #S_X6]
-	ldp x8, x9, [sp, #S_X8]
-	ldp x10, x11, [sp, #S_X10]
-	ldp x12, x13, [sp, #S_X12]
-	ldp x14, x15, [sp, #S_X14]
-	ldp x16, x17, [sp, #S_X16]
-	ldp x18, x19, [sp, #S_X18]
-	ldp x20, x21, [sp, #S_X20]
-	ldp x22, x23, [sp, #S_X22]
-	ldp x24, x25, [sp, #S_X24]
-	ldp x26, x27, [sp, #S_X26]
-	ldp x28, x29, [sp, #S_X28]
-	.endm
-
-SYM_CODE_START(arch_rethook_trampoline)
-	sub sp, sp, #PT_REGS_SIZE
-
-	save_all_base_regs
-
-	/* Setup a frame pointer. */
-	add x29, sp, #S_FP
-
-	mov x0, sp
-	bl arch_rethook_trampoline_callback
-	/*
-	 * Replace trampoline address in lr with actual orig_ret_addr return
-	 * address.
-	 */
-	mov lr, x0
-
-	/* The frame pointer (x29) is restored with other registers. */
-	restore_all_base_regs
-
-	add sp, sp, #PT_REGS_SIZE
-	ret
-
-SYM_CODE_END(arch_rethook_trampoline)

arch/arm64/kernel/stacktrace.c

@@ -8,7 +8,6 @@
 #include <linux/export.h>
 #include <linux/ftrace.h>
 #include <linux/kprobes.h>
-#include <linux/rethook.h>
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/task_stack.h>
@@ -39,7 +38,7 @@ static notrace void start_backtrace(struct stackframe *frame, unsigned long fp,
 {
 	frame->fp = fp;
 	frame->pc = pc;
-#if defined(CONFIG_KRETPROBES) || defined(CONFIG_RETHOOK)
+#ifdef CONFIG_KRETPROBES
 	frame->kr_cur = NULL;
 #endif
 
@@ -139,10 +138,6 @@ static int notrace unwind_frame(struct task_struct *tsk,
 	if (is_kretprobe_trampoline(frame->pc))
 		frame->pc = kretprobe_find_ret_addr(tsk, (void *)frame->fp, &frame->kr_cur);
 #endif
-#ifdef CONFIG_RETHOOK
-	if (is_rethook_trampoline(frame->pc))
-		frame->pc = rethook_find_ret_addr(tsk, frame->fp, &frame->kr_cur);
-#endif
 
 	return 0;
 }