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hc
2023-12-11 072de836f53be56a70cecf70b43ae43b7ce17376 
 kernel/arch/x86/mm/extable.c
....@@ -1,14 +1,17 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 #include <linux/extable.h>
23 #include <linux/uaccess.h>
34 #include <linux/sched/debug.h>
45 #include <xen/xen.h>
56 
67 #include <asm/fpu/internal.h>
8
+#include <asm/sev-es.h>
79 #include <asm/traps.h>
810 #include <asm/kdebug.h>
911 
1012 typedef bool (*ex_handler_t)(const struct exception_table_entry *,
11
-			    struct pt_regs *, int);
13
+			    struct pt_regs *, int, unsigned long,
14
+			    unsigned long);
1215 
1316 static inline unsigned long
1417 ex_fixup_addr(const struct exception_table_entry *x)
....@@ -22,7 +25,9 @@
2225 }
2326 
2427 __visible bool ex_handler_default(const struct exception_table_entry *fixup,
25
-				  struct pt_regs *regs, int trapnr)
28
+				  struct pt_regs *regs, int trapnr,
29
+				  unsigned long error_code,
30
+				  unsigned long fault_addr)
2631 {
2732 	regs->ip = ex_fixup_addr(fixup);
2833 	return true;
....@@ -30,60 +35,15 @@
3035 EXPORT_SYMBOL(ex_handler_default);
3136 
3237 __visible bool ex_handler_fault(const struct exception_table_entry *fixup,
33
-				struct pt_regs *regs, int trapnr)
38
+				struct pt_regs *regs, int trapnr,
39
+				unsigned long error_code,
40
+				unsigned long fault_addr)
3441 {
3542 	regs->ip = ex_fixup_addr(fixup);
3643 	regs->ax = trapnr;
3744 	return true;
3845 }
3946 EXPORT_SYMBOL_GPL(ex_handler_fault);
40
-
41
-/*
42
- * Handler for UD0 exception following a failed test against the
43
- * result of a refcount inc/dec/add/sub.
44
- */
45
-__visible bool ex_handler_refcount(const struct exception_table_entry *fixup,
46
-				   struct pt_regs *regs, int trapnr)
47
-{
48
-	/* First unconditionally saturate the refcount. */
49
-	*(int *)regs->cx = INT_MIN / 2;
50
-
51
-	/*
52
-	 * Strictly speaking, this reports the fixup destination, not
53
-	 * the fault location, and not the actually overflowing
54
-	 * instruction, which is the instruction before the "js", but
55
-	 * since that instruction could be a variety of lengths, just
56
-	 * report the location after the overflow, which should be close
57
-	 * enough for finding the overflow, as it's at least back in
58
-	 * the function, having returned from .text.unlikely.
59
-	 */
60
-	regs->ip = ex_fixup_addr(fixup);
61
-
62
-	/*
63
-	 * This function has been called because either a negative refcount
64
-	 * value was seen by any of the refcount functions, or a zero
65
-	 * refcount value was seen by refcount_dec().
66
-	 *
67
-	 * If we crossed from INT_MAX to INT_MIN, OF (Overflow Flag: result
68
-	 * wrapped around) will be set. Additionally, seeing the refcount
69
-	 * reach 0 will set ZF (Zero Flag: result was zero). In each of
70
-	 * these cases we want a report, since it's a boundary condition.
71
-	 * The SF case is not reported since it indicates post-boundary
72
-	 * manipulations below zero or above INT_MAX. And if none of the
73
-	 * flags are set, something has gone very wrong, so report it.
74
-	 */
75
-	if (regs->flags & (X86_EFLAGS_OF | X86_EFLAGS_ZF)) {
76
-		bool zero = regs->flags & X86_EFLAGS_ZF;
77
-
78
-		refcount_error_report(regs, zero ? "hit zero" : "overflow");
79
-	} else if ((regs->flags & X86_EFLAGS_SF) == 0) {
80
-		/* Report if none of OF, ZF, nor SF are set. */
81
-		refcount_error_report(regs, "unexpected saturation");
82
-	}
83
-
84
-	return true;
85
-}
86
-EXPORT_SYMBOL(ex_handler_refcount);
8747 
8848 /*
8949  * Handler for when we fail to restore a task's FPU state.  We should never get
....@@ -96,7 +56,9 @@
9656  * out all the FPU registers) if we can't restore from the task's FPU state.
9757  */
9858 __visible bool ex_handler_fprestore(const struct exception_table_entry *fixup,
99
-				    struct pt_regs *regs, int trapnr)
59
+				    struct pt_regs *regs, int trapnr,
60
+				    unsigned long error_code,
61
+				    unsigned long fault_addr)
10062 {
10163 	regs->ip = ex_fixup_addr(fixup);
10264 
....@@ -108,20 +70,35 @@
10870 }
10971 EXPORT_SYMBOL_GPL(ex_handler_fprestore);
11072 
111
-__visible bool ex_handler_ext(const struct exception_table_entry *fixup,
112
-			      struct pt_regs *regs, int trapnr)
73
+__visible bool ex_handler_uaccess(const struct exception_table_entry *fixup,
74
+				  struct pt_regs *regs, int trapnr,
75
+				  unsigned long error_code,
76
+				  unsigned long fault_addr)
11377 {
114
-	/* Special hack for uaccess_err */
115
-	current->thread.uaccess_err = 1;
78
+	WARN_ONCE(trapnr == X86_TRAP_GP, "General protection fault in user access. Non-canonical address?");
11679 	regs->ip = ex_fixup_addr(fixup);
11780 	return true;
11881 }
119
-EXPORT_SYMBOL(ex_handler_ext);
82
+EXPORT_SYMBOL(ex_handler_uaccess);
83
+
84
+__visible bool ex_handler_copy(const struct exception_table_entry *fixup,
85
+			       struct pt_regs *regs, int trapnr,
86
+			       unsigned long error_code,
87
+			       unsigned long fault_addr)
88
+{
89
+	WARN_ONCE(trapnr == X86_TRAP_GP, "General protection fault in user access. Non-canonical address?");
90
+	regs->ip = ex_fixup_addr(fixup);
91
+	regs->ax = trapnr;
92
+	return true;
93
+}
94
+EXPORT_SYMBOL(ex_handler_copy);
12095 
12196 __visible bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup,
122
-				       struct pt_regs *regs, int trapnr)
97
+				       struct pt_regs *regs, int trapnr,
98
+				       unsigned long error_code,
99
+				       unsigned long fault_addr)
123100 {
124
-	if (pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pF)\n",
101
+	if (pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pS)\n",
125102 			 (unsigned int)regs->cx, regs->ip, (void *)regs->ip))
126103 		show_stack_regs(regs);
127104 
....@@ -134,9 +111,11 @@
134111 EXPORT_SYMBOL(ex_handler_rdmsr_unsafe);
135112 
136113 __visible bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup,
137
-				       struct pt_regs *regs, int trapnr)
114
+				       struct pt_regs *regs, int trapnr,
115
+				       unsigned long error_code,
116
+				       unsigned long fault_addr)
138117 {
139
-	if (pr_warn_once("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pF)\n",
118
+	if (pr_warn_once("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pS)\n",
140119 			 (unsigned int)regs->cx, (unsigned int)regs->dx,
141120 			 (unsigned int)regs->ax,  regs->ip, (void *)regs->ip))
142121 		show_stack_regs(regs);
....@@ -148,30 +127,37 @@
148127 EXPORT_SYMBOL(ex_handler_wrmsr_unsafe);
149128 
150129 __visible bool ex_handler_clear_fs(const struct exception_table_entry *fixup,
151
-				   struct pt_regs *regs, int trapnr)
130
+				   struct pt_regs *regs, int trapnr,
131
+				   unsigned long error_code,
132
+				   unsigned long fault_addr)
152133 {
153134 	if (static_cpu_has(X86_BUG_NULL_SEG))
154135 		asm volatile ("mov %0, %%fs" : : "rm" (__USER_DS));
155136 	asm volatile ("mov %0, %%fs" : : "rm" (0));
156
-	return ex_handler_default(fixup, regs, trapnr);
137
+	return ex_handler_default(fixup, regs, trapnr, error_code, fault_addr);
157138 }
158139 EXPORT_SYMBOL(ex_handler_clear_fs);
159140 
160
-__visible bool ex_has_fault_handler(unsigned long ip)
141
+enum handler_type ex_get_fault_handler_type(unsigned long ip)
161142 {
162143 	const struct exception_table_entry *e;
163144 	ex_handler_t handler;
164145 
165146 	e = search_exception_tables(ip);
166147 	if (!e)
167
-		return false;
148
+		return EX_HANDLER_NONE;
168149 	handler = ex_fixup_handler(e);
169
-
170
-	return handler == ex_handler_fault;
150
+	if (handler == ex_handler_fault)
151
+		return EX_HANDLER_FAULT;
152
+	else if (handler == ex_handler_uaccess || handler == ex_handler_copy)
153
+		return EX_HANDLER_UACCESS;
154
+	else
155
+		return EX_HANDLER_OTHER;
171156 }
172157 
173158 __nocfi
174
-int fixup_exception(struct pt_regs *regs, int trapnr)
159
+int fixup_exception(struct pt_regs *regs, int trapnr, unsigned long error_code,
160
+		    unsigned long fault_addr)
175161 {
176162 	const struct exception_table_entry *e;
177163 	ex_handler_t handler;
....@@ -195,7 +181,7 @@
195181 		return 0;
196182 
197183 	handler = ex_fixup_handler(e);
198
-	return handler(e, regs, trapnr);
184
+	return handler(e, regs, trapnr, error_code, fault_addr);
199185 }
200186 
201187 extern unsigned int early_recursion_flag;
....@@ -231,13 +217,24 @@
231217 	 * result in a hard-to-debug panic.
232218 	 *
233219 	 * Keep in mind that not all vectors actually get here.  Early
234
-	 * fage faults, for example, are special.
220
+	 * page faults, for example, are special.
235221 	 */
236
-	if (fixup_exception(regs, trapnr))
222
+	if (fixup_exception(regs, trapnr, regs->orig_ax, 0))
237223 		return;
238224 
239
-	if (fixup_bug(regs, trapnr))
240
-		return;
225
+	if (trapnr == X86_TRAP_UD) {
226
+		if (report_bug(regs->ip, regs) == BUG_TRAP_TYPE_WARN) {
227
+			/* Skip the ud2. */
228
+			regs->ip += LEN_UD2;
229
+			return;
230
+		}
231
+
232
+		/*
233
+		 * If this was a BUG and report_bug returns or if this
234
+		 * was just a normal #UD, we want to continue onward and
235
+		 * crash.
236
+		 */
237
+	}
241238 
242239 fail:
243240 	early_printk("PANIC: early exception 0x%02x IP %lx:%lx error %lx cr2 0x%lx\n",