diff options
| -rw-r--r-- | arch/i386/kernel/entry.S | 9 | ||||
| -rw-r--r-- | arch/i386/kernel/process.c | 2 | ||||
| -rw-r--r-- | arch/i386/mm/extable.c | 2 | ||||
| -rw-r--r-- | arch/i386/mm/fault.c | 11 | ||||
| -rw-r--r-- | include/asm-i386/ptrace.h | 5 | ||||
| -rw-r--r-- | include/asm-i386/segment.h | 17 |
6 files changed, 31 insertions, 15 deletions
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S index 3872fca5c74..284f2e908ad 100644 --- a/arch/i386/kernel/entry.S +++ b/arch/i386/kernel/entry.S @@ -240,8 +240,9 @@ ret_from_intr: check_userspace: movl EFLAGS(%esp), %eax # mix EFLAGS and CS movb CS(%esp), %al - testl $(VM_MASK | 3), %eax - jz resume_kernel + andl $(VM_MASK | SEGMENT_RPL_MASK), %eax + cmpl $USER_RPL, %eax + jb resume_kernel # not returning to v8086 or userspace ENTRY(resume_userspace) DISABLE_INTERRUPTS # make sure we don't miss an interrupt # setting need_resched or sigpending @@ -377,8 +378,8 @@ restore_all: # See comments in process.c:copy_thread() for details. movb OLDSS(%esp), %ah movb CS(%esp), %al - andl $(VM_MASK | (4 << 8) | 3), %eax - cmpl $((4 << 8) | 3), %eax + andl $(VM_MASK | (SEGMENT_TI_MASK << 8) | SEGMENT_RPL_MASK), %eax + cmpl $((SEGMENT_LDT << 8) | USER_RPL), %eax CFI_REMEMBER_STATE je ldt_ss # returning to user-space with LDT SS restore_nocheck: diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c index 220aeca59c3..8c190ca7ae4 100644 --- a/arch/i386/kernel/process.c +++ b/arch/i386/kernel/process.c @@ -338,7 +338,7 @@ int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) regs.xes = __USER_DS; regs.orig_eax = -1; regs.eip = (unsigned long) kernel_thread_helper; - regs.xcs = __KERNEL_CS; + regs.xcs = __KERNEL_CS | get_kernel_rpl(); regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2; /* Ok, create the new process.. */ diff --git a/arch/i386/mm/extable.c b/arch/i386/mm/extable.c index de03c5430ab..0ce4f22a263 100644 --- a/arch/i386/mm/extable.c +++ b/arch/i386/mm/extable.c @@ -11,7 +11,7 @@ int fixup_exception(struct pt_regs *regs) const struct exception_table_entry *fixup; #ifdef CONFIG_PNPBIOS - if (unlikely((regs->xcs & ~15) == (GDT_ENTRY_PNPBIOS_BASE << 3))) + if (unlikely(SEGMENT_IS_PNP_CODE(regs->xcs))) { extern u32 pnp_bios_fault_eip, pnp_bios_fault_esp; extern u32 pnp_bios_is_utter_crap; diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c index 0ce86168a0b..5e17a3f43b4 100644 --- a/arch/i386/mm/fault.c +++ b/arch/i386/mm/fault.c @@ -27,6 +27,7 @@ #include <asm/uaccess.h> #include <asm/desc.h> #include <asm/kdebug.h> +#include <asm/segment.h> extern void die(const char *,struct pt_regs *,long); @@ -113,10 +114,10 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs, } /* The standard kernel/user address space limit. */ - *eip_limit = (seg & 3) ? USER_DS.seg : KERNEL_DS.seg; + *eip_limit = user_mode(regs) ? USER_DS.seg : KERNEL_DS.seg; /* By far the most common cases. */ - if (likely(seg == __USER_CS || seg == __KERNEL_CS)) + if (likely(SEGMENT_IS_FLAT_CODE(seg))) return eip; /* Check the segment exists, is within the current LDT/GDT size, @@ -430,11 +431,7 @@ good_area: write = 0; switch (error_code & 3) { default: /* 3: write, present */ -#ifdef TEST_VERIFY_AREA - if (regs->cs == KERNEL_CS) - printk("WP fault at %08lx\n", regs->eip); -#endif - /* fall through */ + /* fall through */ case 2: /* write, not present */ if (!(vma->vm_flags & VM_WRITE)) goto bad_area; diff --git a/include/asm-i386/ptrace.h b/include/asm-i386/ptrace.h index 30a442ec205..21bb91679c8 100644 --- a/include/asm-i386/ptrace.h +++ b/include/asm-i386/ptrace.h @@ -60,6 +60,7 @@ struct pt_regs { #ifdef __KERNEL__ #include <asm/vm86.h> +#include <asm/segment.h> struct task_struct; extern void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code); @@ -73,11 +74,11 @@ extern void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int erro */ static inline int user_mode(struct pt_regs *regs) { - return (regs->xcs & 3) != 0; + return (regs->xcs & SEGMENT_RPL_MASK) == USER_RPL; } static inline int user_mode_vm(struct pt_regs *regs) { - return ((regs->xcs & 3) | (regs->eflags & VM_MASK)) != 0; + return ((regs->xcs & SEGMENT_RPL_MASK) | (regs->eflags & VM_MASK)) >= USER_RPL; } #define instruction_pointer(regs) ((regs)->eip) extern unsigned long profile_pc(struct pt_regs *regs); diff --git a/include/asm-i386/segment.h b/include/asm-i386/segment.h index faf995307b9..b7ab59685ba 100644 --- a/include/asm-i386/segment.h +++ b/include/asm-i386/segment.h @@ -83,6 +83,11 @@ #define GDT_SIZE (GDT_ENTRIES * 8) +/* Matches __KERNEL_CS and __USER_CS (they must be 2 entries apart) */ +#define SEGMENT_IS_FLAT_CODE(x) (((x) & 0xec) == GDT_ENTRY_KERNEL_CS * 8) +/* Matches PNP_CS32 and PNP_CS16 (they must be consecutive) */ +#define SEGMENT_IS_PNP_CODE(x) (((x) & 0xf4) == GDT_ENTRY_PNPBIOS_BASE * 8) + /* Simple and small GDT entries for booting only */ #define GDT_ENTRY_BOOT_CS 2 @@ -112,4 +117,16 @@ */ #define IDT_ENTRIES 256 +/* Bottom two bits of selector give the ring privilege level */ +#define SEGMENT_RPL_MASK 0x3 +/* Bit 2 is table indicator (LDT/GDT) */ +#define SEGMENT_TI_MASK 0x4 + +/* User mode is privilege level 3 */ +#define USER_RPL 0x3 +/* LDT segment has TI set, GDT has it cleared */ +#define SEGMENT_LDT 0x4 +#define SEGMENT_GDT 0x0 + +#define get_kernel_rpl() 0 #endif |