Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) // SPDX-License-Identifier: GPL-2.0-or-later
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3)  *  Kernel Probes Jump Optimization (Optprobes)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5)  * Copyright (C) IBM Corporation, 2002, 2004
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6)  * Copyright (C) Hitachi Ltd., 2012
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7)  * Copyright (C) Huawei Inc., 2014
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10) #include <linux/kprobes.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11) #include <linux/jump_label.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12) #include <asm/kprobes.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13) #include <asm/cacheflush.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14) /* for arm_gen_branch */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15) #include <asm/insn.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16) /* for patch_text */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17) #include <asm/patch.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19) #include "core.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22)  * See register_usage_flags. If the probed instruction doesn't use PC,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23)  * we can copy it into template and have it executed directly without
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24)  * simulation or emulation.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26) #define ARM_REG_PC	15
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27) #define can_kprobe_direct_exec(m)	(!test_bit(ARM_REG_PC, &(m)))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30)  * NOTE: the first sub and add instruction will be modified according
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31)  * to the stack cost of the instruction.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33) asm (
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) 			".global optprobe_template_entry\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) 			"optprobe_template_entry:\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) 			".global optprobe_template_sub_sp\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) 			"optprobe_template_sub_sp:"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) 			"	sub	sp, sp, #0xff\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) 			"	stmia	sp, {r0 - r14} \n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) 			".global optprobe_template_add_sp\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) 			"optprobe_template_add_sp:"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) 			"	add	r3, sp, #0xff\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43) 			"	str	r3, [sp, #52]\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44) 			"	mrs	r4, cpsr\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45) 			"	str	r4, [sp, #64]\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46) 			"	mov	r1, sp\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47) 			"	ldr	r0, 1f\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48) 			"	ldr	r2, 2f\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49) 			/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50) 			 * AEABI requires an 8-bytes alignment stack. If
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51) 			 * SP % 8 != 0 (SP % 4 == 0 should be ensured),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52) 			 * alloc more bytes here.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53) 			 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54) 			"	and	r4, sp, #4\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55) 			"	sub	sp, sp, r4\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56) #if __LINUX_ARM_ARCH__ >= 5
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57) 			"	blx	r2\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58) #else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59) 			"	mov     lr, pc\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60) 			"	mov	pc, r2\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61) #endif
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62) 			"	add	sp, sp, r4\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63) 			"	ldr	r1, [sp, #64]\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64) 			"	tst	r1, #"__stringify(PSR_T_BIT)"\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65) 			"	ldrne	r2, [sp, #60]\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66) 			"	orrne	r2, #1\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) 			"	strne	r2, [sp, #60] @ set bit0 of PC for thumb\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) 			"	msr	cpsr_cxsf, r1\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) 			".global optprobe_template_restore_begin\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70) 			"optprobe_template_restore_begin:\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71) 			"	ldmia	sp, {r0 - r15}\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72) 			".global optprobe_template_restore_orig_insn\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73) 			"optprobe_template_restore_orig_insn:\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74) 			"	nop\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75) 			".global optprobe_template_restore_end\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76) 			"optprobe_template_restore_end:\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77) 			"	nop\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78) 			".global optprobe_template_val\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79) 			"optprobe_template_val:\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80) 			"1:	.long 0\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81) 			".global optprobe_template_call\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82) 			"optprobe_template_call:\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83) 			"2:	.long 0\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84) 			".global optprobe_template_end\n"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85) 			"optprobe_template_end:\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87) #define TMPL_VAL_IDX \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88) 	((unsigned long *)optprobe_template_val - (unsigned long *)optprobe_template_entry)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) #define TMPL_CALL_IDX \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) 	((unsigned long *)optprobe_template_call - (unsigned long *)optprobe_template_entry)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) #define TMPL_END_IDX \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) 	((unsigned long *)optprobe_template_end - (unsigned long *)optprobe_template_entry)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) #define TMPL_ADD_SP \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) 	((unsigned long *)optprobe_template_add_sp - (unsigned long *)optprobe_template_entry)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95) #define TMPL_SUB_SP \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96) 	((unsigned long *)optprobe_template_sub_sp - (unsigned long *)optprobe_template_entry)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97) #define TMPL_RESTORE_BEGIN \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98) 	((unsigned long *)optprobe_template_restore_begin - (unsigned long *)optprobe_template_entry)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99) #define TMPL_RESTORE_ORIGN_INSN \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) 	((unsigned long *)optprobe_template_restore_orig_insn - (unsigned long *)optprobe_template_entry)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) #define TMPL_RESTORE_END \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) 	((unsigned long *)optprobe_template_restore_end - (unsigned long *)optprobe_template_entry)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105)  * ARM can always optimize an instruction when using ARM ISA, except
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106)  * instructions like 'str r0, [sp, r1]' which store to stack and unable
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107)  * to determine stack space consumption statically.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) int arch_prepared_optinsn(struct arch_optimized_insn *optinsn)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) 	return optinsn->insn != NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115)  * In ARM ISA, kprobe opt always replace one instruction (4 bytes
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116)  * aligned and 4 bytes long). It is impossible to encounter another
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117)  * kprobe in the address range. So always return 0.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) int arch_check_optimized_kprobe(struct optimized_kprobe *op)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) 	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) /* Caller must ensure addr & 3 == 0 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) static int can_optimize(struct kprobe *kp)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) 	if (kp->ainsn.stack_space < 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) 		return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) 	 * 255 is the biggest imm can be used in 'sub r0, r0, #<imm>'.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) 	 * Number larger than 255 needs special encoding.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) 	if (kp->ainsn.stack_space > 255 - sizeof(struct pt_regs))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) 		return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) 	return 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) /* Free optimized instruction slot */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) static void
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) __arch_remove_optimized_kprobe(struct optimized_kprobe *op, int dirty)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) 	if (op->optinsn.insn) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) 		free_optinsn_slot(op->optinsn.insn, dirty);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) 		op->optinsn.insn = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) extern void kprobe_handler(struct pt_regs *regs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) static void
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) 	unsigned long flags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) 	struct kprobe *p = &op->kp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) 	struct kprobe_ctlblk *kcb;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) 	/* Save skipped registers */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) 	regs->ARM_pc = (unsigned long)op->kp.addr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) 	regs->ARM_ORIG_r0 = ~0UL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) 	local_irq_save(flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) 	kcb = get_kprobe_ctlblk();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) 	if (kprobe_running()) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) 		kprobes_inc_nmissed_count(&op->kp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) 	} else {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) 		__this_cpu_write(current_kprobe, &op->kp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) 		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) 		opt_pre_handler(&op->kp, regs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) 		__this_cpu_write(current_kprobe, NULL);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) 	 * We singlestep the replaced instruction only when it can't be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) 	 * executed directly during restore.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) 	if (!p->ainsn.kprobe_direct_exec)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) 		op->kp.ainsn.insn_singlestep(p->opcode, &p->ainsn, regs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) 	local_irq_restore(flags);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) NOKPROBE_SYMBOL(optimized_callback)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *orig)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) 	kprobe_opcode_t *code;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) 	unsigned long rel_chk;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) 	unsigned long val;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) 	unsigned long stack_protect = sizeof(struct pt_regs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) 	if (!can_optimize(orig))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) 		return -EILSEQ;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) 	code = get_optinsn_slot();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) 	if (!code)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) 		return -ENOMEM;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) 	 * Verify if the address gap is in 32MiB range, because this uses
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) 	 * a relative jump.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) 	 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) 	 * kprobe opt use a 'b' instruction to branch to optinsn.insn.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) 	 * According to ARM manual, branch instruction is:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) 	 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) 	 *   31  28 27           24 23             0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) 	 *  +------+---+---+---+---+----------------+
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) 	 *  | cond | 1 | 0 | 1 | 0 |      imm24     |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) 	 *  +------+---+---+---+---+----------------+
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) 	 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) 	 * imm24 is a signed 24 bits integer. The real branch offset is computed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) 	 * by: imm32 = SignExtend(imm24:'00', 32);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) 	 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) 	 * So the maximum forward branch should be:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) 	 *   (0x007fffff << 2) = 0x01fffffc =  0x1fffffc
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) 	 * The maximum backword branch should be:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) 	 *   (0xff800000 << 2) = 0xfe000000 = -0x2000000
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) 	 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) 	 * We can simply check (rel & 0xfe000003):
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) 	 *  if rel is positive, (rel & 0xfe000000) shoule be 0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) 	 *  if rel is negitive, (rel & 0xfe000000) should be 0xfe000000
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) 	 *  the last '3' is used for alignment checking.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) 	rel_chk = (unsigned long)((long)code -
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) 			(long)orig->addr + 8) & 0xfe000003;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) 	if ((rel_chk != 0) && (rel_chk != 0xfe000000)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) 		/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) 		 * Different from x86, we free code buf directly instead of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) 		 * calling __arch_remove_optimized_kprobe() because
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) 		 * we have not fill any field in op.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) 		free_optinsn_slot(code, 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) 		return -ERANGE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) 	/* Copy arch-dep-instance from template. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) 	memcpy(code, (unsigned long *)optprobe_template_entry,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) 			TMPL_END_IDX * sizeof(kprobe_opcode_t));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) 	/* Adjust buffer according to instruction. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) 	BUG_ON(orig->ainsn.stack_space < 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) 	stack_protect += orig->ainsn.stack_space;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) 	/* Should have been filtered by can_optimize(). */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) 	BUG_ON(stack_protect > 255);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) 	/* Create a 'sub sp, sp, #<stack_protect>' */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) 	code[TMPL_SUB_SP] = __opcode_to_mem_arm(0xe24dd000 | stack_protect);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) 	/* Create a 'add r3, sp, #<stack_protect>' */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) 	code[TMPL_ADD_SP] = __opcode_to_mem_arm(0xe28d3000 | stack_protect);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) 	/* Set probe information */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254) 	val = (unsigned long)op;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255) 	code[TMPL_VAL_IDX] = val;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) 	/* Set probe function call */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258) 	val = (unsigned long)optimized_callback;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) 	code[TMPL_CALL_IDX] = val;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261) 	/* If possible, copy insn and have it executed during restore */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) 	orig->ainsn.kprobe_direct_exec = false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) 	if (can_kprobe_direct_exec(orig->ainsn.register_usage_flags)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264) 		kprobe_opcode_t final_branch = arm_gen_branch(
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265) 				(unsigned long)(&code[TMPL_RESTORE_END]),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) 				(unsigned long)(op->kp.addr) + 4);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267) 		if (final_branch != 0) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268) 			/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269) 			 * Replace original 'ldmia sp, {r0 - r15}' with
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270) 			 * 'ldmia {r0 - r14}', restore all registers except pc.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271) 			 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272) 			code[TMPL_RESTORE_BEGIN] = __opcode_to_mem_arm(0xe89d7fff);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) 			/* The original probed instruction */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275) 			code[TMPL_RESTORE_ORIGN_INSN] = __opcode_to_mem_arm(orig->opcode);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277) 			/* Jump back to next instruction */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278) 			code[TMPL_RESTORE_END] = __opcode_to_mem_arm(final_branch);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) 			orig->ainsn.kprobe_direct_exec = true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283) 	flush_icache_range((unsigned long)code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284) 			   (unsigned long)(&code[TMPL_END_IDX]));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286) 	/* Set op->optinsn.insn means prepared. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287) 	op->optinsn.insn = code;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288) 	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291) void __kprobes arch_optimize_kprobes(struct list_head *oplist)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293) 	struct optimized_kprobe *op, *tmp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295) 	list_for_each_entry_safe(op, tmp, oplist, list) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) 		unsigned long insn;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297) 		WARN_ON(kprobe_disabled(&op->kp));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) 		/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300) 		 * Backup instructions which will be replaced
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) 		 * by jump address
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 302) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 303) 		memcpy(op->optinsn.copied_insn, op->kp.addr,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 304) 				RELATIVEJUMP_SIZE);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 305) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 306) 		insn = arm_gen_branch((unsigned long)op->kp.addr,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 307) 				(unsigned long)op->optinsn.insn);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 308) 		BUG_ON(insn == 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 309) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 310) 		/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 311) 		 * Make it a conditional branch if replaced insn
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 312) 		 * is consitional
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 313) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 314) 		insn = (__mem_to_opcode_arm(
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 315) 			  op->optinsn.copied_insn[0]) & 0xf0000000) |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 316) 			(insn & 0x0fffffff);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 317) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 318) 		/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 319) 		 * Similar to __arch_disarm_kprobe, operations which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 320) 		 * removing breakpoints must be wrapped by stop_machine
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 321) 		 * to avoid racing.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 322) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 323) 		kprobes_remove_breakpoint(op->kp.addr, insn);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 324) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 325) 		list_del_init(&op->list);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 326) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 327) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 328) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 329) void arch_unoptimize_kprobe(struct optimized_kprobe *op)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 330) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 331) 	arch_arm_kprobe(&op->kp);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 332) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 333) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 334) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 335)  * Recover original instructions and breakpoints from relative jumps.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 336)  * Caller must call with locking kprobe_mutex.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 337)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 338) void arch_unoptimize_kprobes(struct list_head *oplist,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 339) 			    struct list_head *done_list)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 340) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 341) 	struct optimized_kprobe *op, *tmp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 342) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 343) 	list_for_each_entry_safe(op, tmp, oplist, list) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 344) 		arch_unoptimize_kprobe(op);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 345) 		list_move(&op->list, done_list);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 346) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 347) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 348) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 349) int arch_within_optimized_kprobe(struct optimized_kprobe *op,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 350) 				unsigned long addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 351) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 352) 	return ((unsigned long)op->kp.addr <= addr &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 353) 		(unsigned long)op->kp.addr + RELATIVEJUMP_SIZE > addr);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 354) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 355) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 356) void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 357) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 358) 	__arch_remove_optimized_kprobe(op, 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 359) }