diff options
Diffstat (limited to 'arch/x86/mm/extable.c')
-rw-r--r-- | arch/x86/mm/extable.c | 197 |
1 files changed, 108 insertions, 89 deletions
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index e1664e9f969c..a9c7efd4b794 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -2,48 +2,50 @@ #include <linux/extable.h> #include <linux/uaccess.h> #include <linux/sched/debug.h> +#include <linux/bitfield.h> #include <xen/xen.h> #include <asm/fpu/internal.h> #include <asm/sev.h> #include <asm/traps.h> #include <asm/kdebug.h> +#include <asm/insn-eval.h> -typedef bool (*ex_handler_t)(const struct exception_table_entry *, - struct pt_regs *, int, unsigned long, - unsigned long); +static inline unsigned long *pt_regs_nr(struct pt_regs *regs, int nr) +{ + int reg_offset = pt_regs_offset(regs, nr); + static unsigned long __dummy; + + if (WARN_ON_ONCE(reg_offset < 0)) + return &__dummy; + + return (unsigned long *)((unsigned long)regs + reg_offset); +} static inline unsigned long ex_fixup_addr(const struct exception_table_entry *x) { return (unsigned long)&x->fixup + x->fixup; } -static inline ex_handler_t -ex_fixup_handler(const struct exception_table_entry *x) -{ - return (ex_handler_t)((unsigned long)&x->handler + x->handler); -} -__visible bool ex_handler_default(const struct exception_table_entry *fixup, - struct pt_regs *regs, int trapnr, - unsigned long error_code, - unsigned long fault_addr) +static bool ex_handler_default(const struct exception_table_entry *e, + struct pt_regs *regs) { - regs->ip = ex_fixup_addr(fixup); + if (e->data & EX_FLAG_CLEAR_AX) + regs->ax = 0; + if (e->data & EX_FLAG_CLEAR_DX) + regs->dx = 0; + + regs->ip = ex_fixup_addr(e); return true; } -EXPORT_SYMBOL(ex_handler_default); -__visible bool ex_handler_fault(const struct exception_table_entry *fixup, - struct pt_regs *regs, int trapnr, - unsigned long error_code, - unsigned long fault_addr) +static bool ex_handler_fault(const struct exception_table_entry *fixup, + struct pt_regs *regs, int trapnr) { - regs->ip = ex_fixup_addr(fixup); regs->ax = trapnr; - return true; + return ex_handler_default(fixup, regs); } -EXPORT_SYMBOL_GPL(ex_handler_fault); /* * Handler for when we fail to restore a task's FPU state. We should never get @@ -55,10 +57,8 @@ EXPORT_SYMBOL_GPL(ex_handler_fault); * of vulnerability by restoring from the initial state (essentially, zeroing * out all the FPU registers) if we can't restore from the task's FPU state. */ -__visible bool ex_handler_fprestore(const struct exception_table_entry *fixup, - struct pt_regs *regs, int trapnr, - unsigned long error_code, - unsigned long fault_addr) +static bool ex_handler_fprestore(const struct exception_table_entry *fixup, + struct pt_regs *regs) { regs->ip = ex_fixup_addr(fixup); @@ -68,98 +68,77 @@ __visible bool ex_handler_fprestore(const struct exception_table_entry *fixup, __restore_fpregs_from_fpstate(&init_fpstate, xfeatures_mask_fpstate()); return true; } -EXPORT_SYMBOL_GPL(ex_handler_fprestore); -__visible bool ex_handler_uaccess(const struct exception_table_entry *fixup, - struct pt_regs *regs, int trapnr, - unsigned long error_code, - unsigned long fault_addr) +static bool ex_handler_uaccess(const struct exception_table_entry *fixup, + struct pt_regs *regs, int trapnr) { WARN_ONCE(trapnr == X86_TRAP_GP, "General protection fault in user access. Non-canonical address?"); - regs->ip = ex_fixup_addr(fixup); - return true; + return ex_handler_default(fixup, regs); } -EXPORT_SYMBOL(ex_handler_uaccess); -__visible bool ex_handler_copy(const struct exception_table_entry *fixup, - struct pt_regs *regs, int trapnr, - unsigned long error_code, - unsigned long fault_addr) +static bool ex_handler_copy(const struct exception_table_entry *fixup, + struct pt_regs *regs, int trapnr) { WARN_ONCE(trapnr == X86_TRAP_GP, "General protection fault in user access. Non-canonical address?"); - regs->ip = ex_fixup_addr(fixup); - regs->ax = trapnr; - return true; + return ex_handler_fault(fixup, regs, trapnr); } -EXPORT_SYMBOL(ex_handler_copy); -__visible bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup, - struct pt_regs *regs, int trapnr, - unsigned long error_code, - unsigned long fault_addr) +static bool ex_handler_msr(const struct exception_table_entry *fixup, + struct pt_regs *regs, bool wrmsr, bool safe, int reg) { - if (pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pS)\n", - (unsigned int)regs->cx, regs->ip, (void *)regs->ip)) + if (__ONCE_LITE_IF(!safe && wrmsr)) { + pr_warn("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pS)\n", + (unsigned int)regs->cx, (unsigned int)regs->dx, + (unsigned int)regs->ax, regs->ip, (void *)regs->ip); show_stack_regs(regs); + } - /* Pretend that the read succeeded and returned 0. */ - regs->ip = ex_fixup_addr(fixup); - regs->ax = 0; - regs->dx = 0; - return true; -} -EXPORT_SYMBOL(ex_handler_rdmsr_unsafe); - -__visible bool ex_handler_wrmsr_unsafe(const struct exception_table_entry *fixup, - struct pt_regs *regs, int trapnr, - unsigned long error_code, - unsigned long fault_addr) -{ - if (pr_warn_once("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pS)\n", - (unsigned int)regs->cx, (unsigned int)regs->dx, - (unsigned int)regs->ax, regs->ip, (void *)regs->ip)) + if (__ONCE_LITE_IF(!safe && !wrmsr)) { + pr_warn("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pS)\n", + (unsigned int)regs->cx, regs->ip, (void *)regs->ip); show_stack_regs(regs); + } - /* Pretend that the write succeeded. */ - regs->ip = ex_fixup_addr(fixup); - return true; + if (!wrmsr) { + /* Pretend that the read succeeded and returned 0. */ + regs->ax = 0; + regs->dx = 0; + } + + if (safe) + *pt_regs_nr(regs, reg) = -EIO; + + return ex_handler_default(fixup, regs); } -EXPORT_SYMBOL(ex_handler_wrmsr_unsafe); -__visible bool ex_handler_clear_fs(const struct exception_table_entry *fixup, - struct pt_regs *regs, int trapnr, - unsigned long error_code, - unsigned long fault_addr) +static bool ex_handler_clear_fs(const struct exception_table_entry *fixup, + struct pt_regs *regs) { if (static_cpu_has(X86_BUG_NULL_SEG)) asm volatile ("mov %0, %%fs" : : "rm" (__USER_DS)); asm volatile ("mov %0, %%fs" : : "rm" (0)); - return ex_handler_default(fixup, regs, trapnr, error_code, fault_addr); + return ex_handler_default(fixup, regs); } -EXPORT_SYMBOL(ex_handler_clear_fs); -enum handler_type ex_get_fault_handler_type(unsigned long ip) +static bool ex_handler_imm_reg(const struct exception_table_entry *fixup, + struct pt_regs *regs, int reg, int imm) { - const struct exception_table_entry *e; - ex_handler_t handler; + *pt_regs_nr(regs, reg) = (long)imm; + return ex_handler_default(fixup, regs); +} - e = search_exception_tables(ip); - if (!e) - return EX_HANDLER_NONE; - handler = ex_fixup_handler(e); - if (handler == ex_handler_fault) - return EX_HANDLER_FAULT; - else if (handler == ex_handler_uaccess || handler == ex_handler_copy) - return EX_HANDLER_UACCESS; - else - return EX_HANDLER_OTHER; +int ex_get_fixup_type(unsigned long ip) +{ + const struct exception_table_entry *e = search_exception_tables(ip); + + return e ? FIELD_GET(EX_DATA_TYPE_MASK, e->data) : EX_TYPE_NONE; } int fixup_exception(struct pt_regs *regs, int trapnr, unsigned long error_code, unsigned long fault_addr) { const struct exception_table_entry *e; - ex_handler_t handler; + int type, reg, imm; #ifdef CONFIG_PNPBIOS if (unlikely(SEGMENT_IS_PNP_CODE(regs->cs))) { @@ -179,8 +158,48 @@ int fixup_exception(struct pt_regs *regs, int trapnr, unsigned long error_code, if (!e) return 0; - handler = ex_fixup_handler(e); - return handler(e, regs, trapnr, error_code, fault_addr); + type = FIELD_GET(EX_DATA_TYPE_MASK, e->data); + reg = FIELD_GET(EX_DATA_REG_MASK, e->data); + imm = FIELD_GET(EX_DATA_IMM_MASK, e->data); + + switch (type) { + case EX_TYPE_DEFAULT: + case EX_TYPE_DEFAULT_MCE_SAFE: + return ex_handler_default(e, regs); + case EX_TYPE_FAULT: + case EX_TYPE_FAULT_MCE_SAFE: + return ex_handler_fault(e, regs, trapnr); + case EX_TYPE_UACCESS: + return ex_handler_uaccess(e, regs, trapnr); + case EX_TYPE_COPY: + return ex_handler_copy(e, regs, trapnr); + case EX_TYPE_CLEAR_FS: + return ex_handler_clear_fs(e, regs); + case EX_TYPE_FPU_RESTORE: + return ex_handler_fprestore(e, regs); + case EX_TYPE_BPF: + return ex_handler_bpf(e, regs); + case EX_TYPE_WRMSR: + return ex_handler_msr(e, regs, true, false, reg); + case EX_TYPE_RDMSR: + return ex_handler_msr(e, regs, false, false, reg); + case EX_TYPE_WRMSR_SAFE: + return ex_handler_msr(e, regs, true, true, reg); + case EX_TYPE_RDMSR_SAFE: + return ex_handler_msr(e, regs, false, true, reg); + case EX_TYPE_WRMSR_IN_MCE: + ex_handler_msr_mce(regs, true); + break; + case EX_TYPE_RDMSR_IN_MCE: + ex_handler_msr_mce(regs, false); + break; + case EX_TYPE_POP_REG: + regs->sp += sizeof(long); + fallthrough; + case EX_TYPE_IMM_REG: + return ex_handler_imm_reg(e, regs, reg, imm); + } + BUG(); } extern unsigned int early_recursion_flag; |