extern struct cpuinfo_x86 boot_cpu_data;
extern struct cpuinfo_x86 new_cpu_data;
-extern struct tss_struct doublefault_tss;
-extern __u32 cpu_caps_cleared[NCAPINTS];
-extern __u32 cpu_caps_set[NCAPINTS];
+extern struct x86_hw_tss doublefault_tss;
+extern __u32 cpu_caps_cleared[NCAPINTS + NBUGINTS];
+extern __u32 cpu_caps_set[NCAPINTS + NBUGINTS];
#ifdef CONFIG_SMP
DECLARE_PER_CPU_READ_MOSTLY(struct cpuinfo_x86, cpu_info);
write_cr3(__sme_pa(pgdir));
}
+/*
+ * Note that while the legacy 'TSS' name comes from 'Task State Segment',
+ * on modern x86 CPUs the TSS also holds information important to 64-bit mode,
+ * unrelated to the task-switch mechanism:
+ */
#ifdef CONFIG_X86_32
/* This is the TSS defined by the hardware. */
struct x86_hw_tss {
struct x86_hw_tss {
u32 reserved1;
u64 sp0;
+
+ /*
+ * We store cpu_current_top_of_stack in sp1 so it's always accessible.
+ * Linux does not use ring 1, so sp1 is not otherwise needed.
+ */
u64 sp1;
+
u64 sp2;
u64 reserved2;
u64 ist[7];
#define IO_BITMAP_BITS 65536
#define IO_BITMAP_BYTES (IO_BITMAP_BITS/8)
#define IO_BITMAP_LONGS (IO_BITMAP_BYTES/sizeof(long))
-#define IO_BITMAP_OFFSET offsetof(struct tss_struct, io_bitmap)
+#define IO_BITMAP_OFFSET (offsetof(struct tss_struct, io_bitmap) - offsetof(struct tss_struct, x86_tss))
#define INVALID_IO_BITMAP_OFFSET 0x8000
+struct entry_stack {
+ unsigned long words[64];
+};
+
+struct entry_stack_page {
+ struct entry_stack stack;
+} __aligned(PAGE_SIZE);
+
struct tss_struct {
/*
- * The hardware state:
+ * The fixed hardware portion. This must not cross a page boundary
+ * at risk of violating the SDM's advice and potentially triggering
+ * errata.
*/
struct x86_hw_tss x86_tss;
* be within the limit.
*/
unsigned long io_bitmap[IO_BITMAP_LONGS + 1];
+} __aligned(PAGE_SIZE);
-#ifdef CONFIG_X86_32
- /*
- * Space for the temporary SYSENTER stack.
- */
- unsigned long SYSENTER_stack_canary;
- unsigned long SYSENTER_stack[64];
-#endif
-
-} ____cacheline_aligned;
-
-DECLARE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss);
+DECLARE_PER_CPU_PAGE_ALIGNED(struct tss_struct, cpu_tss_rw);
/*
* sizeof(unsigned long) coming from an extra "long" at the end
#ifdef CONFIG_X86_32
DECLARE_PER_CPU(unsigned long, cpu_current_top_of_stack);
+#else
+/* The RO copy can't be accessed with this_cpu_xyz(), so use the RW copy. */
+#define cpu_current_top_of_stack cpu_tss_rw.x86_tss.sp1
#endif
/*
static inline void
native_load_sp0(unsigned long sp0)
{
- this_cpu_write(cpu_tss.x86_tss.sp0, sp0);
+ this_cpu_write(cpu_tss_rw.x86_tss.sp0, sp0);
}
static inline void native_swapgs(void)
static inline unsigned long current_top_of_stack(void)
{
-#ifdef CONFIG_X86_64
- return this_cpu_read_stable(cpu_tss.x86_tss.sp0);
-#else
- /* sp0 on x86_32 is special in and around vm86 mode. */
+ /*
+ * We can't read directly from tss.sp0: sp0 on x86_32 is special in
+ * and around vm86 mode and sp0 on x86_64 is special because of the
+ * entry trampoline.
+ */
return this_cpu_read_stable(cpu_current_top_of_stack);
-#endif
}
static inline bool on_thread_stack(void)
#else
/*
- * User space process size. 47bits minus one guard page. The guard
- * page is necessary on Intel CPUs: if a SYSCALL instruction is at
- * the highest possible canonical userspace address, then that
- * syscall will enter the kernel with a non-canonical return
- * address, and SYSRET will explode dangerously. We avoid this
- * particular problem by preventing anything from being mapped
- * at the maximum canonical address.
+ * User space process size. This is the first address outside the user range.
+ * There are a few constraints that determine this:
+ *
+ * On Intel CPUs, if a SYSCALL instruction is at the highest canonical
+ * address, then that syscall will enter the kernel with a
+ * non-canonical return address, and SYSRET will explode dangerously.
+ * We avoid this particular problem by preventing anything executable
+ * from being mapped at the maximum canonical address.
+ *
+ * On AMD CPUs in the Ryzen family, there's a nasty bug in which the
+ * CPUs malfunction if they execute code from the highest canonical page.
+ * They'll speculate right off the end of the canonical space, and
+ * bad things happen. This is worked around in the same way as the
+ * Intel problem.
+ *
+ * With page table isolation enabled, we map the LDT in ... [stay tuned]
*/
#define TASK_SIZE_MAX ((1UL << __VIRTUAL_MASK_SHIFT) - PAGE_SIZE)
void stop_this_cpu(void *dummy);
void df_debug(struct pt_regs *regs, long error_code);
+
+void __ibp_barrier(void);
+
#endif /* _ASM_X86_PROCESSOR_H */
projects / linux-2.6-block.git / blobdiff