Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) // SPDX-License-Identifier: GPL-2.0-only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) #include <linux/extable.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3) #include <linux/uaccess.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4) #include <linux/sched/debug.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5) #include <xen/xen.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7) #include <asm/fpu/internal.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8) #include <asm/sev-es.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9) #include <asm/traps.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10) #include <asm/kdebug.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12) typedef bool (*ex_handler_t)(const struct exception_table_entry *,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13) 			    struct pt_regs *, int, unsigned long,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14) 			    unsigned long);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16) static inline unsigned long
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17) ex_fixup_addr(const struct exception_table_entry *x)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19) 	return (unsigned long)&x->fixup + x->fixup;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21) static inline ex_handler_t
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22) ex_fixup_handler(const struct exception_table_entry *x)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24) 	return (ex_handler_t)((unsigned long)&x->handler + x->handler);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27) __visible bool ex_handler_default(const struct exception_table_entry *fixup,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28) 				  struct pt_regs *regs, int trapnr,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29) 				  unsigned long error_code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30) 				  unsigned long fault_addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32) 	regs->ip = ex_fixup_addr(fixup);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33) 	return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) EXPORT_SYMBOL(ex_handler_default);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) __visible bool ex_handler_fault(const struct exception_table_entry *fixup,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) 				struct pt_regs *regs, int trapnr,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) 				unsigned long error_code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) 				unsigned long fault_addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) 	regs->ip = ex_fixup_addr(fixup);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43) 	regs->ax = trapnr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44) 	return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46) EXPORT_SYMBOL_GPL(ex_handler_fault);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49)  * Handler for when we fail to restore a task's FPU state.  We should never get
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50)  * here because the FPU state of a task using the FPU (task->thread.fpu.state)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51)  * should always be valid.  However, past bugs have allowed userspace to set
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52)  * reserved bits in the XSAVE area using PTRACE_SETREGSET or sys_rt_sigreturn().
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53)  * These caused XRSTOR to fail when switching to the task, leaking the FPU
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54)  * registers of the task previously executing on the CPU.  Mitigate this class
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55)  * of vulnerability by restoring from the initial state (essentially, zeroing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56)  * out all the FPU registers) if we can't restore from the task's FPU state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58) __visible bool ex_handler_fprestore(const struct exception_table_entry *fixup,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59) 				    struct pt_regs *regs, int trapnr,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60) 				    unsigned long error_code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61) 				    unsigned long fault_addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63) 	regs->ip = ex_fixup_addr(fixup);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65) 	WARN_ONCE(1, "Bad FPU state detected at %pB, reinitializing FPU registers.",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66) 		  (void *)instruction_pointer(regs));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) 	__copy_kernel_to_fpregs(&init_fpstate, -1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) 	return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71) EXPORT_SYMBOL_GPL(ex_handler_fprestore);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73) __visible bool ex_handler_uaccess(const struct exception_table_entry *fixup,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74) 				  struct pt_regs *regs, int trapnr,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75) 				  unsigned long error_code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76) 				  unsigned long fault_addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78) 	WARN_ONCE(trapnr == X86_TRAP_GP, "General protection fault in user access. Non-canonical address?");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79) 	regs->ip = ex_fixup_addr(fixup);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80) 	return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82) EXPORT_SYMBOL(ex_handler_uaccess);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84) __visible bool ex_handler_copy(const struct exception_table_entry *fixup,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85) 			       struct pt_regs *regs, int trapnr,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) 			       unsigned long error_code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87) 			       unsigned long fault_addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) 	WARN_ONCE(trapnr == X86_TRAP_GP, "General protection fault in user access. Non-canonical address?");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) 	regs->ip = ex_fixup_addr(fixup);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) 	regs->ax = trapnr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) 	return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) EXPORT_SYMBOL(ex_handler_copy);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96) __visible bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97) 				       struct pt_regs *regs, int trapnr,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98) 				       unsigned long error_code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99) 				       unsigned long fault_addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) 	if (pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pS)\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) 			 (unsigned int)regs->cx, regs->ip, (void *)regs->ip))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) 		show_stack_regs(regs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) 	/* Pretend that the read succeeded and returned 0. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) 	regs->ip = ex_fixup_addr(fixup);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) 	regs->ax = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) 	regs->dx = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) 	return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) EXPORT_SYMBOL(ex_handler_rdmsr_unsafe);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) __visible bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) 				       struct pt_regs *regs, int trapnr,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) 				       unsigned long error_code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) 				       unsigned long fault_addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 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",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) 			 (unsigned int)regs->cx, (unsigned int)regs->dx,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) 			 (unsigned int)regs->ax,  regs->ip, (void *)regs->ip))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) 		show_stack_regs(regs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) 	/* Pretend that the write succeeded. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) 	regs->ip = ex_fixup_addr(fixup);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) 	return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) EXPORT_SYMBOL(ex_handler_wrmsr_unsafe);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) __visible bool ex_handler_clear_fs(const struct exception_table_entry *fixup,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) 				   struct pt_regs *regs, int trapnr,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) 				   unsigned long error_code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) 				   unsigned long fault_addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) 	if (static_cpu_has(X86_BUG_NULL_SEG))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) 		asm volatile ("mov %0, %%fs" : : "rm" (__USER_DS));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) 	asm volatile ("mov %0, %%fs" : : "rm" (0));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) 	return ex_handler_default(fixup, regs, trapnr, error_code, fault_addr);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) EXPORT_SYMBOL(ex_handler_clear_fs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) enum handler_type ex_get_fault_handler_type(unsigned long ip)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) 	const struct exception_table_entry *e;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) 	ex_handler_t handler;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) 	e = search_exception_tables(ip);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) 	if (!e)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) 		return EX_HANDLER_NONE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) 	handler = ex_fixup_handler(e);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) 	if (handler == ex_handler_fault)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) 		return EX_HANDLER_FAULT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) 	else if (handler == ex_handler_uaccess || handler == ex_handler_copy)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) 		return EX_HANDLER_UACCESS;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) 	else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) 		return EX_HANDLER_OTHER;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) __nocfi
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) int fixup_exception(struct pt_regs *regs, int trapnr, unsigned long error_code,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) 		    unsigned long fault_addr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) 	const struct exception_table_entry *e;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) 	ex_handler_t handler;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) #ifdef CONFIG_PNPBIOS
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) 	if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) 		extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) 		extern u32 pnp_bios_is_utter_crap;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) 		pnp_bios_is_utter_crap = 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) 		printk(KERN_CRIT "PNPBIOS fault.. attempting recovery.\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) 		__asm__ volatile(
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) 			"movl %0, %%esp\n\t"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) 			"jmp *%1\n\t"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) 			: : "g" (pnp_bios_fault_esp), "g" (pnp_bios_fault_eip));
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) 		panic("do_trap: can't hit this");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) #endif
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) 	e = search_exception_tables(regs->ip);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) 	if (!e)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) 		return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) 	handler = ex_fixup_handler(e);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) 	return handler(e, regs, trapnr, error_code, fault_addr);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) extern unsigned int early_recursion_flag;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) /* Restricted version used during very early boot */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) void __init early_fixup_exception(struct pt_regs *regs, int trapnr)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) 	/* Ignore early NMIs. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) 	if (trapnr == X86_TRAP_NMI)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) 	if (early_recursion_flag > 2)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) 		goto halt_loop;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) 	 * Old CPUs leave the high bits of CS on the stack
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) 	 * undefined.  I'm not sure which CPUs do this, but at least
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) 	 * the 486 DX works this way.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) 	 * Xen pv domains are not using the default __KERNEL_CS.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) 	if (!xen_pv_domain() && regs->cs != __KERNEL_CS)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) 		goto fail;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) 	 * The full exception fixup machinery is available as soon as
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) 	 * the early IDT is loaded.  This means that it is the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) 	 * responsibility of extable users to either function correctly
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) 	 * when handlers are invoked early or to simply avoid causing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) 	 * exceptions before they're ready to handle them.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) 	 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) 	 * This is better than filtering which handlers can be used,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) 	 * because refusing to call a handler here is guaranteed to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) 	 * result in a hard-to-debug panic.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) 	 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) 	 * Keep in mind that not all vectors actually get here.  Early
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) 	 * page faults, for example, are special.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) 	if (fixup_exception(regs, trapnr, regs->orig_ax, 0))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) 		return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) 	if (trapnr == X86_TRAP_UD) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) 		if (report_bug(regs->ip, regs) == BUG_TRAP_TYPE_WARN) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) 			/* Skip the ud2. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) 			regs->ip += LEN_UD2;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) 			return;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) 		/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) 		 * If this was a BUG and report_bug returns or if this
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) 		 * was just a normal #UD, we want to continue onward and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) 		 * crash.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) fail:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) 	early_printk("PANIC: early exception 0x%02x IP %lx:%lx error %lx cr2 0x%lx\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) 		     (unsigned)trapnr, (unsigned long)regs->cs, regs->ip,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) 		     regs->orig_ax, read_cr2());
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) 	show_regs(regs);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) halt_loop:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) 	while (true)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) 		halt();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) }