From 2f7c68cb55ecb7331f2381deb497c27155f32faf Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Wed, 03 Jan 2024 09:43:39 +0000
Subject: [PATCH] update kernel to 5.10.198

---
 kernel/arch/x86/kernel/kprobes/core.c |  670 ++++++++++++++++++++++++++++++++++---------------------
 1 files changed, 410 insertions(+), 260 deletions(-)

diff --git a/kernel/arch/x86/kernel/kprobes/core.c b/kernel/arch/x86/kernel/kprobes/core.c
index ee85f1b..c78b494 100644
--- a/kernel/arch/x86/kernel/kprobes/core.c
+++ b/kernel/arch/x86/kernel/kprobes/core.c
@@ -37,6 +37,7 @@
 #include <linux/extable.h>
 #include <linux/kdebug.h>
 #include <linux/kallsyms.h>
+#include <linux/kgdb.h>
 #include <linux/ftrace.h>
 #include <linux/kasan.h>
 #include <linux/moduleloader.h>
@@ -133,26 +134,6 @@
 NOKPROBE_SYMBOL(synthesize_relcall);
 
 /*
- * Skip the prefixes of the instruction.
- */
-static kprobe_opcode_t *skip_prefixes(kprobe_opcode_t *insn)
-{
-	insn_attr_t attr;
-
-	attr = inat_get_opcode_attribute((insn_byte_t)*insn);
-	while (inat_is_legacy_prefix(attr)) {
-		insn++;
-		attr = inat_get_opcode_attribute((insn_byte_t)*insn);
-	}
-#ifdef CONFIG_X86_64
-	if (inat_is_rex_prefix(attr))
-		insn++;
-#endif
-	return insn;
-}
-NOKPROBE_SYMBOL(skip_prefixes);
-
-/*
  * Returns non-zero if INSN is boostable.
  * RIP relative instructions are adjusted at copying time in 64 bits mode
  */
@@ -184,29 +165,28 @@
 
 	opcode = insn->opcode.bytes[0];
 
-	switch (opcode & 0xf0) {
-	case 0x60:
-		/* can't boost "bound" */
-		return (opcode != 0x62);
-	case 0x70:
-		return 0; /* can't boost conditional jump */
-	case 0x90:
-		return opcode != 0x9a;	/* can't boost call far */
-	case 0xc0:
-		/* can't boost software-interruptions */
-		return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf;
-	case 0xd0:
-		/* can boost AA* and XLAT */
-		return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7);
-	case 0xe0:
-		/* can boost in/out and absolute jmps */
-		return ((opcode & 0x04) || opcode == 0xea);
-	case 0xf0:
-		/* clear and set flags are boostable */
-		return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
+	switch (opcode) {
+	case 0x62:		/* bound */
+	case 0x70 ... 0x7f:	/* Conditional jumps */
+	case 0x9a:		/* Call far */
+	case 0xc0 ... 0xc1:	/* Grp2 */
+	case 0xcc ... 0xce:	/* software exceptions */
+	case 0xd0 ... 0xd3:	/* Grp2 */
+	case 0xd6:		/* (UD) */
+	case 0xd8 ... 0xdf:	/* ESC */
+	case 0xe0 ... 0xe3:	/* LOOP*, JCXZ */
+	case 0xe8 ... 0xe9:	/* near Call, JMP */
+	case 0xeb:		/* Short JMP */
+	case 0xf0 ... 0xf4:	/* LOCK/REP, HLT */
+	case 0xf6 ... 0xf7:	/* Grp3 */
+	case 0xfe:		/* Grp4 */
+		/* ... are not boostable */
+		return 0;
+	case 0xff:		/* Grp5 */
+		/* Only indirect jmp is boostable */
+		return X86_MODRM_REG(insn->modrm.bytes[0]) == 4;
 	default:
-		/* call is not boostable */
-		return opcode != 0x9a;
+		return 1;
 	}
 }
 
@@ -292,6 +272,8 @@
 	/* Decode instructions */
 	addr = paddr - offset;
 	while (addr < paddr) {
+		int ret;
+
 		/*
 		 * Check if the instruction has been modified by another
 		 * kprobe, in which case we replace the breakpoint by the
@@ -303,38 +285,24 @@
 		__addr = recover_probed_instruction(buf, addr);
 		if (!__addr)
 			return 0;
-		kernel_insn_init(&insn, (void *)__addr, MAX_INSN_SIZE);
-		insn_get_length(&insn);
 
-		/*
-		 * Another debugging subsystem might insert this breakpoint.
-		 * In that case, we can't recover it.
-		 */
-		if (insn.opcode.bytes[0] == INT3_INSN_OPCODE)
+		ret = insn_decode(&insn, (void *)__addr, MAX_INSN_SIZE, INSN_MODE_KERN);
+		if (ret < 0)
 			return 0;
+
+#ifdef CONFIG_KGDB
+		/*
+		 * If there is a dynamically installed kgdb sw breakpoint,
+		 * this function should not be probed.
+		 */
+		if (insn.opcode.bytes[0] == INT3_INSN_OPCODE &&
+		    kgdb_has_hit_break(addr))
+			return 0;
+#endif
 		addr += insn.length;
 	}
 
 	return (addr == paddr);
-}
-
-/*
- * Returns non-zero if opcode modifies the interrupt flag.
- */
-static int is_IF_modifier(kprobe_opcode_t *insn)
-{
-	/* Skip prefixes */
-	insn = skip_prefixes(insn);
-
-	switch (*insn) {
-	case 0xfa:		/* cli */
-	case 0xfb:		/* sti */
-	case 0xcf:		/* iret/iretd */
-	case 0x9d:		/* popf/popfd */
-		return 1;
-	}
-
-	return 0;
 }
 
 /*
@@ -347,8 +315,8 @@
 int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
 {
 	kprobe_opcode_t buf[MAX_INSN_SIZE];
-	unsigned long recovered_insn =
-		recover_probed_instruction(buf, (unsigned long)src);
+	unsigned long recovered_insn = recover_probed_instruction(buf, (unsigned long)src);
+	int ret;
 
 	if (!recovered_insn || !insn)
 		return 0;
@@ -358,8 +326,9 @@
 			MAX_INSN_SIZE))
 		return 0;
 
-	kernel_insn_init(insn, dest, MAX_INSN_SIZE);
-	insn_get_length(insn);
+	ret = insn_decode(insn, dest, MAX_INSN_SIZE, INSN_MODE_KERN);
+	if (ret < 0)
+		return 0;
 
 	/* We can not probe force emulate prefixed instruction */
 	if (insn_has_emulate_prefix(insn))
@@ -403,13 +372,14 @@
 	return insn->length;
 }
 
-/* Prepare reljump right after instruction to boost */
-static int prepare_boost(kprobe_opcode_t *buf, struct kprobe *p,
-			  struct insn *insn)
+/* Prepare reljump or int3 right after instruction */
+static int prepare_singlestep(kprobe_opcode_t *buf, struct kprobe *p,
+			      struct insn *insn)
 {
 	int len = insn->length;
 
-	if (can_boost(insn, p->addr) &&
+	if (!IS_ENABLED(CONFIG_PREEMPTION) &&
+	    !p->post_handler && can_boost(insn, p->addr) &&
 	    MAX_INSN_SIZE - len >= JMP32_INSN_SIZE) {
 		/*
 		 * These instructions can be executed directly if it
@@ -418,9 +388,14 @@
 		synthesize_reljump(buf + len, p->ainsn.insn + len,
 				   p->addr + insn->length);
 		len += JMP32_INSN_SIZE;
-		p->ainsn.boostable = true;
+		p->ainsn.boostable = 1;
 	} else {
-		p->ainsn.boostable = false;
+		/* Otherwise, put an int3 for trapping singlestep */
+		if (MAX_INSN_SIZE - len < INT3_INSN_SIZE)
+			return -ENOSPC;
+
+		buf[len] = INT3_INSN_OPCODE;
+		len += INT3_INSN_SIZE;
 	}
 
 	return len;
@@ -457,25 +432,290 @@
 	module_memfree(page);
 }
 
+/* Kprobe x86 instruction emulation - only regs->ip or IF flag modifiers */
+
+static void kprobe_emulate_ifmodifiers(struct kprobe *p, struct pt_regs *regs)
+{
+	switch (p->ainsn.opcode) {
+	case 0xfa:	/* cli */
+		regs->flags &= ~(X86_EFLAGS_IF);
+		break;
+	case 0xfb:	/* sti */
+		regs->flags |= X86_EFLAGS_IF;
+		break;
+	case 0x9c:	/* pushf */
+		int3_emulate_push(regs, regs->flags);
+		break;
+	case 0x9d:	/* popf */
+		regs->flags = int3_emulate_pop(regs);
+		break;
+	}
+	regs->ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size;
+}
+NOKPROBE_SYMBOL(kprobe_emulate_ifmodifiers);
+
+static void kprobe_emulate_ret(struct kprobe *p, struct pt_regs *regs)
+{
+	int3_emulate_ret(regs);
+}
+NOKPROBE_SYMBOL(kprobe_emulate_ret);
+
+static void kprobe_emulate_call(struct kprobe *p, struct pt_regs *regs)
+{
+	unsigned long func = regs->ip - INT3_INSN_SIZE + p->ainsn.size;
+
+	func += p->ainsn.rel32;
+	int3_emulate_call(regs, func);
+}
+NOKPROBE_SYMBOL(kprobe_emulate_call);
+
+static nokprobe_inline
+void __kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs, bool cond)
+{
+	unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size;
+
+	if (cond)
+		ip += p->ainsn.rel32;
+	int3_emulate_jmp(regs, ip);
+}
+
+static void kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs)
+{
+	__kprobe_emulate_jmp(p, regs, true);
+}
+NOKPROBE_SYMBOL(kprobe_emulate_jmp);
+
+static const unsigned long jcc_mask[6] = {
+	[0] = X86_EFLAGS_OF,
+	[1] = X86_EFLAGS_CF,
+	[2] = X86_EFLAGS_ZF,
+	[3] = X86_EFLAGS_CF | X86_EFLAGS_ZF,
+	[4] = X86_EFLAGS_SF,
+	[5] = X86_EFLAGS_PF,
+};
+
+static void kprobe_emulate_jcc(struct kprobe *p, struct pt_regs *regs)
+{
+	bool invert = p->ainsn.jcc.type & 1;
+	bool match;
+
+	if (p->ainsn.jcc.type < 0xc) {
+		match = regs->flags & jcc_mask[p->ainsn.jcc.type >> 1];
+	} else {
+		match = ((regs->flags & X86_EFLAGS_SF) >> X86_EFLAGS_SF_BIT) ^
+			((regs->flags & X86_EFLAGS_OF) >> X86_EFLAGS_OF_BIT);
+		if (p->ainsn.jcc.type >= 0xe)
+			match = match || (regs->flags & X86_EFLAGS_ZF);
+	}
+	__kprobe_emulate_jmp(p, regs, (match && !invert) || (!match && invert));
+}
+NOKPROBE_SYMBOL(kprobe_emulate_jcc);
+
+static void kprobe_emulate_loop(struct kprobe *p, struct pt_regs *regs)
+{
+	bool match;
+
+	if (p->ainsn.loop.type != 3) {	/* LOOP* */
+		if (p->ainsn.loop.asize == 32)
+			match = ((*(u32 *)&regs->cx)--) != 0;
+#ifdef CONFIG_X86_64
+		else if (p->ainsn.loop.asize == 64)
+			match = ((*(u64 *)&regs->cx)--) != 0;
+#endif
+		else
+			match = ((*(u16 *)&regs->cx)--) != 0;
+	} else {			/* JCXZ */
+		if (p->ainsn.loop.asize == 32)
+			match = *(u32 *)(&regs->cx) == 0;
+#ifdef CONFIG_X86_64
+		else if (p->ainsn.loop.asize == 64)
+			match = *(u64 *)(&regs->cx) == 0;
+#endif
+		else
+			match = *(u16 *)(&regs->cx) == 0;
+	}
+
+	if (p->ainsn.loop.type == 0)	/* LOOPNE */
+		match = match && !(regs->flags & X86_EFLAGS_ZF);
+	else if (p->ainsn.loop.type == 1)	/* LOOPE */
+		match = match && (regs->flags & X86_EFLAGS_ZF);
+
+	__kprobe_emulate_jmp(p, regs, match);
+}
+NOKPROBE_SYMBOL(kprobe_emulate_loop);
+
+static const int addrmode_regoffs[] = {
+	offsetof(struct pt_regs, ax),
+	offsetof(struct pt_regs, cx),
+	offsetof(struct pt_regs, dx),
+	offsetof(struct pt_regs, bx),
+	offsetof(struct pt_regs, sp),
+	offsetof(struct pt_regs, bp),
+	offsetof(struct pt_regs, si),
+	offsetof(struct pt_regs, di),
+#ifdef CONFIG_X86_64
+	offsetof(struct pt_regs, r8),
+	offsetof(struct pt_regs, r9),
+	offsetof(struct pt_regs, r10),
+	offsetof(struct pt_regs, r11),
+	offsetof(struct pt_regs, r12),
+	offsetof(struct pt_regs, r13),
+	offsetof(struct pt_regs, r14),
+	offsetof(struct pt_regs, r15),
+#endif
+};
+
+static void kprobe_emulate_call_indirect(struct kprobe *p, struct pt_regs *regs)
+{
+	unsigned long offs = addrmode_regoffs[p->ainsn.indirect.reg];
+
+	int3_emulate_call(regs, regs_get_register(regs, offs));
+}
+NOKPROBE_SYMBOL(kprobe_emulate_call_indirect);
+
+static void kprobe_emulate_jmp_indirect(struct kprobe *p, struct pt_regs *regs)
+{
+	unsigned long offs = addrmode_regoffs[p->ainsn.indirect.reg];
+
+	int3_emulate_jmp(regs, regs_get_register(regs, offs));
+}
+NOKPROBE_SYMBOL(kprobe_emulate_jmp_indirect);
+
+static int prepare_emulation(struct kprobe *p, struct insn *insn)
+{
+	insn_byte_t opcode = insn->opcode.bytes[0];
+
+	switch (opcode) {
+	case 0xfa:		/* cli */
+	case 0xfb:		/* sti */
+	case 0x9c:		/* pushfl */
+	case 0x9d:		/* popf/popfd */
+		/*
+		 * IF modifiers must be emulated since it will enable interrupt while
+		 * int3 single stepping.
+		 */
+		p->ainsn.emulate_op = kprobe_emulate_ifmodifiers;
+		p->ainsn.opcode = opcode;
+		break;
+	case 0xc2:	/* ret/lret */
+	case 0xc3:
+	case 0xca:
+	case 0xcb:
+		p->ainsn.emulate_op = kprobe_emulate_ret;
+		break;
+	case 0x9a:	/* far call absolute -- segment is not supported */
+	case 0xea:	/* far jmp absolute -- segment is not supported */
+	case 0xcc:	/* int3 */
+	case 0xcf:	/* iret -- in-kernel IRET is not supported */
+		return -EOPNOTSUPP;
+		break;
+	case 0xe8:	/* near call relative */
+		p->ainsn.emulate_op = kprobe_emulate_call;
+		if (insn->immediate.nbytes == 2)
+			p->ainsn.rel32 = *(s16 *)&insn->immediate.value;
+		else
+			p->ainsn.rel32 = *(s32 *)&insn->immediate.value;
+		break;
+	case 0xeb:	/* short jump relative */
+	case 0xe9:	/* near jump relative */
+		p->ainsn.emulate_op = kprobe_emulate_jmp;
+		if (insn->immediate.nbytes == 1)
+			p->ainsn.rel32 = *(s8 *)&insn->immediate.value;
+		else if (insn->immediate.nbytes == 2)
+			p->ainsn.rel32 = *(s16 *)&insn->immediate.value;
+		else
+			p->ainsn.rel32 = *(s32 *)&insn->immediate.value;
+		break;
+	case 0x70 ... 0x7f:
+		/* 1 byte conditional jump */
+		p->ainsn.emulate_op = kprobe_emulate_jcc;
+		p->ainsn.jcc.type = opcode & 0xf;
+		p->ainsn.rel32 = *(char *)insn->immediate.bytes;
+		break;
+	case 0x0f:
+		opcode = insn->opcode.bytes[1];
+		if ((opcode & 0xf0) == 0x80) {
+			/* 2 bytes Conditional Jump */
+			p->ainsn.emulate_op = kprobe_emulate_jcc;
+			p->ainsn.jcc.type = opcode & 0xf;
+			if (insn->immediate.nbytes == 2)
+				p->ainsn.rel32 = *(s16 *)&insn->immediate.value;
+			else
+				p->ainsn.rel32 = *(s32 *)&insn->immediate.value;
+		} else if (opcode == 0x01 &&
+			   X86_MODRM_REG(insn->modrm.bytes[0]) == 0 &&
+			   X86_MODRM_MOD(insn->modrm.bytes[0]) == 3) {
+			/* VM extensions - not supported */
+			return -EOPNOTSUPP;
+		}
+		break;
+	case 0xe0:	/* Loop NZ */
+	case 0xe1:	/* Loop */
+	case 0xe2:	/* Loop */
+	case 0xe3:	/* J*CXZ */
+		p->ainsn.emulate_op = kprobe_emulate_loop;
+		p->ainsn.loop.type = opcode & 0x3;
+		p->ainsn.loop.asize = insn->addr_bytes * 8;
+		p->ainsn.rel32 = *(s8 *)&insn->immediate.value;
+		break;
+	case 0xff:
+		/*
+		 * Since the 0xff is an extended group opcode, the instruction
+		 * is determined by the MOD/RM byte.
+		 */
+		opcode = insn->modrm.bytes[0];
+		if ((opcode & 0x30) == 0x10) {
+			if ((opcode & 0x8) == 0x8)
+				return -EOPNOTSUPP;	/* far call */
+			/* call absolute, indirect */
+			p->ainsn.emulate_op = kprobe_emulate_call_indirect;
+		} else if ((opcode & 0x30) == 0x20) {
+			if ((opcode & 0x8) == 0x8)
+				return -EOPNOTSUPP;	/* far jmp */
+			/* jmp near absolute indirect */
+			p->ainsn.emulate_op = kprobe_emulate_jmp_indirect;
+		} else
+			break;
+
+		if (insn->addr_bytes != sizeof(unsigned long))
+			return -EOPNOTSUPP;	/* Don't support differnt size */
+		if (X86_MODRM_MOD(opcode) != 3)
+			return -EOPNOTSUPP;	/* TODO: support memory addressing */
+
+		p->ainsn.indirect.reg = X86_MODRM_RM(opcode);
+#ifdef CONFIG_X86_64
+		if (X86_REX_B(insn->rex_prefix.value))
+			p->ainsn.indirect.reg += 8;
+#endif
+		break;
+	default:
+		break;
+	}
+	p->ainsn.size = insn->length;
+
+	return 0;
+}
+
 static int arch_copy_kprobe(struct kprobe *p)
 {
 	struct insn insn;
 	kprobe_opcode_t buf[MAX_INSN_SIZE];
-	int len;
+	int ret, len;
 
 	/* Copy an instruction with recovering if other optprobe modifies it.*/
 	len = __copy_instruction(buf, p->addr, p->ainsn.insn, &insn);
 	if (!len)
 		return -EINVAL;
 
-	/*
-	 * __copy_instruction can modify the displacement of the instruction,
-	 * but it doesn't affect boostable check.
-	 */
-	len = prepare_boost(buf, p, &insn);
+	/* Analyze the opcode and setup emulate functions */
+	ret = prepare_emulation(p, &insn);
+	if (ret < 0)
+		return ret;
 
-	/* Check whether the instruction modifies Interrupt Flag or not */
-	p->ainsn.if_modifier = is_IF_modifier(buf);
+	/* Add int3 for single-step or booster jmp */
+	len = prepare_singlestep(buf, p, &insn);
+	if (len < 0)
+		return len;
 
 	/* Also, displacement change doesn't affect the first byte */
 	p->opcode = buf[0];
@@ -498,6 +738,9 @@
 
 	if (!can_probe((unsigned long)p->addr))
 		return -EILSEQ;
+
+	memset(&p->ainsn, 0, sizeof(p->ainsn));
+
 	/* insn: must be on special executable page on x86. */
 	p->ainsn.insn = get_insn_slot();
 	if (!p->ainsn.insn)
@@ -565,29 +808,7 @@
 {
 	__this_cpu_write(current_kprobe, p);
 	kcb->kprobe_saved_flags = kcb->kprobe_old_flags
-		= (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF));
-	if (p->ainsn.if_modifier)
-		kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF;
-}
-
-static nokprobe_inline void clear_btf(void)
-{
-	if (test_thread_flag(TIF_BLOCKSTEP)) {
-		unsigned long debugctl = get_debugctlmsr();
-
-		debugctl &= ~DEBUGCTLMSR_BTF;
-		update_debugctlmsr(debugctl);
-	}
-}
-
-static nokprobe_inline void restore_btf(void)
-{
-	if (test_thread_flag(TIF_BLOCKSTEP)) {
-		unsigned long debugctl = get_debugctlmsr();
-
-		debugctl |= DEBUGCTLMSR_BTF;
-		update_debugctlmsr(debugctl);
-	}
+		= (regs->flags & X86_EFLAGS_IF);
 }
 
 void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
@@ -602,6 +823,26 @@
 }
 NOKPROBE_SYMBOL(arch_prepare_kretprobe);
 
+static void kprobe_post_process(struct kprobe *cur, struct pt_regs *regs,
+			       struct kprobe_ctlblk *kcb)
+{
+	/* Restore back the original saved kprobes variables and continue. */
+	if (kcb->kprobe_status == KPROBE_REENTER) {
+		/* This will restore both kcb and current_kprobe */
+		restore_previous_kprobe(kcb);
+	} else {
+		/*
+		 * Always update the kcb status because
+		 * reset_curent_kprobe() doesn't update kcb.
+		 */
+		kcb->kprobe_status = KPROBE_HIT_SSDONE;
+		if (cur->post_handler)
+			cur->post_handler(cur, regs, 0);
+		reset_current_kprobe();
+	}
+}
+NOKPROBE_SYMBOL(kprobe_post_process);
+
 static void setup_singlestep(struct kprobe *p, struct pt_regs *regs,
 			     struct kprobe_ctlblk *kcb, int reenter)
 {
@@ -609,7 +850,7 @@
 		return;
 
 #if !defined(CONFIG_PREEMPTION)
-	if (p->ainsn.boostable && !p->post_handler) {
+	if (p->ainsn.boostable) {
 		/* Boost up -- we can execute copied instructions directly */
 		if (!reenter)
 			reset_current_kprobe();
@@ -628,17 +869,49 @@
 		kcb->kprobe_status = KPROBE_REENTER;
 	} else
 		kcb->kprobe_status = KPROBE_HIT_SS;
-	/* Prepare real single stepping */
-	clear_btf();
-	regs->flags |= X86_EFLAGS_TF;
+
+	if (p->ainsn.emulate_op) {
+		p->ainsn.emulate_op(p, regs);
+		kprobe_post_process(p, regs, kcb);
+		return;
+	}
+
+	/* Disable interrupt, and set ip register on trampoline */
 	regs->flags &= ~X86_EFLAGS_IF;
-	/* single step inline if the instruction is an int3 */
-	if (p->opcode == INT3_INSN_OPCODE)
-		regs->ip = (unsigned long)p->addr;
-	else
-		regs->ip = (unsigned long)p->ainsn.insn;
+	regs->ip = (unsigned long)p->ainsn.insn;
 }
 NOKPROBE_SYMBOL(setup_singlestep);
+
+/*
+ * Called after single-stepping.  p->addr is the address of the
+ * instruction whose first byte has been replaced by the "int3"
+ * instruction.  To avoid the SMP problems that can occur when we
+ * temporarily put back the original opcode to single-step, we
+ * single-stepped a copy of the instruction.  The address of this
+ * copy is p->ainsn.insn. We also doesn't use trap, but "int3" again
+ * right after the copied instruction.
+ * Different from the trap single-step, "int3" single-step can not
+ * handle the instruction which changes the ip register, e.g. jmp,
+ * call, conditional jmp, and the instructions which changes the IF
+ * flags because interrupt must be disabled around the single-stepping.
+ * Such instructions are software emulated, but others are single-stepped
+ * using "int3".
+ *
+ * When the 2nd "int3" handled, the regs->ip and regs->flags needs to
+ * be adjusted, so that we can resume execution on correct code.
+ */
+static void resume_singlestep(struct kprobe *p, struct pt_regs *regs,
+			      struct kprobe_ctlblk *kcb)
+{
+	unsigned long copy_ip = (unsigned long)p->ainsn.insn;
+	unsigned long orig_ip = (unsigned long)p->addr;
+
+	/* Restore saved interrupt flag and ip register */
+	regs->flags |= kcb->kprobe_saved_flags;
+	/* Note that regs->ip is executed int3 so must be a step back */
+	regs->ip += (orig_ip - copy_ip) - INT3_INSN_SIZE;
+}
+NOKPROBE_SYMBOL(resume_singlestep);
 
 /*
  * We have reentered the kprobe_handler(), since another probe was hit while
@@ -674,6 +947,12 @@
 	return 1;
 }
 NOKPROBE_SYMBOL(reenter_kprobe);
+
+static nokprobe_inline int kprobe_is_ss(struct kprobe_ctlblk *kcb)
+{
+	return (kcb->kprobe_status == KPROBE_HIT_SS ||
+		kcb->kprobe_status == KPROBE_REENTER);
+}
 
 /*
  * Interrupts are disabled on entry as trap3 is an interrupt gate and they
@@ -719,7 +998,18 @@
 				reset_current_kprobe();
 			return 1;
 		}
-	} else if (*addr != INT3_INSN_OPCODE) {
+	} else if (kprobe_is_ss(kcb)) {
+		p = kprobe_running();
+		if ((unsigned long)p->ainsn.insn < regs->ip &&
+		    (unsigned long)p->ainsn.insn + MAX_INSN_SIZE > regs->ip) {
+			/* Most provably this is the second int3 for singlestep */
+			resume_singlestep(p, regs, kcb);
+			kprobe_post_process(p, regs, kcb);
+			return 1;
+		}
+	}
+
+	if (*addr != INT3_INSN_OPCODE) {
 		/*
 		 * The breakpoint instruction was removed right
 		 * after we hit it.  Another cpu has removed
@@ -792,135 +1082,6 @@
 }
 NOKPROBE_SYMBOL(trampoline_handler);
 
-/*
- * Called after single-stepping.  p->addr is the address of the
- * instruction whose first byte has been replaced by the "int 3"
- * instruction.  To avoid the SMP problems that can occur when we
- * temporarily put back the original opcode to single-step, we
- * single-stepped a copy of the instruction.  The address of this
- * copy is p->ainsn.insn.
- *
- * This function prepares to return from the post-single-step
- * interrupt.  We have to fix up the stack as follows:
- *
- * 0) Except in the case of absolute or indirect jump or call instructions,
- * the new ip is relative to the copied instruction.  We need to make
- * it relative to the original instruction.
- *
- * 1) If the single-stepped instruction was pushfl, then the TF and IF
- * flags are set in the just-pushed flags, and may need to be cleared.
- *
- * 2) If the single-stepped instruction was a call, the return address
- * that is atop the stack is the address following the copied instruction.
- * We need to make it the address following the original instruction.
- *
- * If this is the first time we've single-stepped the instruction at
- * this probepoint, and the instruction is boostable, boost it: add a
- * jump instruction after the copied instruction, that jumps to the next
- * instruction after the probepoint.
- */
-static void resume_execution(struct kprobe *p, struct pt_regs *regs,
-			     struct kprobe_ctlblk *kcb)
-{
-	unsigned long *tos = stack_addr(regs);
-	unsigned long copy_ip = (unsigned long)p->ainsn.insn;
-	unsigned long orig_ip = (unsigned long)p->addr;
-	kprobe_opcode_t *insn = p->ainsn.insn;
-
-	/* Skip prefixes */
-	insn = skip_prefixes(insn);
-
-	regs->flags &= ~X86_EFLAGS_TF;
-	switch (*insn) {
-	case 0x9c:	/* pushfl */
-		*tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF);
-		*tos |= kcb->kprobe_old_flags;
-		break;
-	case 0xc2:	/* iret/ret/lret */
-	case 0xc3:
-	case 0xca:
-	case 0xcb:
-	case 0xcf:
-	case 0xea:	/* jmp absolute -- ip is correct */
-		/* ip is already adjusted, no more changes required */
-		p->ainsn.boostable = true;
-		goto no_change;
-	case 0xe8:	/* call relative - Fix return addr */
-		*tos = orig_ip + (*tos - copy_ip);
-		break;
-#ifdef CONFIG_X86_32
-	case 0x9a:	/* call absolute -- same as call absolute, indirect */
-		*tos = orig_ip + (*tos - copy_ip);
-		goto no_change;
-#endif
-	case 0xff:
-		if ((insn[1] & 0x30) == 0x10) {
-			/*
-			 * call absolute, indirect
-			 * Fix return addr; ip is correct.
-			 * But this is not boostable
-			 */
-			*tos = orig_ip + (*tos - copy_ip);
-			goto no_change;
-		} else if (((insn[1] & 0x31) == 0x20) ||
-			   ((insn[1] & 0x31) == 0x21)) {
-			/*
-			 * jmp near and far, absolute indirect
-			 * ip is correct. And this is boostable
-			 */
-			p->ainsn.boostable = true;
-			goto no_change;
-		}
-	default:
-		break;
-	}
-
-	regs->ip += orig_ip - copy_ip;
-
-no_change:
-	restore_btf();
-}
-NOKPROBE_SYMBOL(resume_execution);
-
-/*
- * Interrupts are disabled on entry as trap1 is an interrupt gate and they
- * remain disabled throughout this function.
- */
-int kprobe_debug_handler(struct pt_regs *regs)
-{
-	struct kprobe *cur = kprobe_running();
-	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
-
-	if (!cur)
-		return 0;
-
-	resume_execution(cur, regs, kcb);
-	regs->flags |= kcb->kprobe_saved_flags;
-
-	if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
-		kcb->kprobe_status = KPROBE_HIT_SSDONE;
-		cur->post_handler(cur, regs, 0);
-	}
-
-	/* Restore back the original saved kprobes variables and continue. */
-	if (kcb->kprobe_status == KPROBE_REENTER) {
-		restore_previous_kprobe(kcb);
-		goto out;
-	}
-	reset_current_kprobe();
-out:
-	/*
-	 * if somebody else is singlestepping across a probe point, flags
-	 * will have TF set, in which case, continue the remaining processing
-	 * of do_debug, as if this is not a probe hit.
-	 */
-	if (regs->flags & X86_EFLAGS_TF)
-		return 0;
-
-	return 1;
-}
-NOKPROBE_SYMBOL(kprobe_debug_handler);
-
 int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 {
 	struct kprobe *cur = kprobe_running();
@@ -938,20 +1099,9 @@
 		 * normal page fault.
 		 */
 		regs->ip = (unsigned long)cur->addr;
-		/*
-		 * Trap flag (TF) has been set here because this fault
-		 * happened where the single stepping will be done.
-		 * So clear it by resetting the current kprobe:
-		 */
-		regs->flags &= ~X86_EFLAGS_TF;
-		/*
-		 * Since the single step (trap) has been cancelled,
-		 * we need to restore BTF here.
-		 */
-		restore_btf();
 
 		/*
-		 * If the TF flag was set before the kprobe hit,
+		 * If the IF flag was set before the kprobe hit,
 		 * don't touch it:
 		 */
 		regs->flags |= kcb->kprobe_old_flags;

--
Gitblit v1.6.2