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x86/entry: Clean up the SYSENTER_stack code 

The existing code was a mess, mainly because C arrays are nasty.  Turn
SYSENTER_stack into a struct, add a helper to find it, and do all the
obvious cleanups this enables.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bpetkov@suse.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Link: https://lkml.kernel.org/r/20171204150606.653244723@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2017-12-04 15:07:28 +01:00 committed by Ingo Molnar
parent 7fbbd5cbeb
commit 0f9a48100f
7 changed files with 21 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/x86/entry/entry_32.S
View File

@ -942,7 +942,7 @@ ENTRY(debug)
/* Are we currently on the SYSENTER stack? */
movl PER_CPU_VAR(cpu_entry_area), %ecx
addl $CPU_ENTRY_AREA_tss + CPU_TSS_SYSENTER_stack + SIZEOF_SYSENTER_stack, %ecx
addl $CPU_ENTRY_AREA_tss + TSS_STRUCT_SYSENTER_stack + SIZEOF_SYSENTER_stack, %ecx
subl %eax, %ecx /* ecx = (end of SYSENTER_stack) - esp */
cmpl $SIZEOF_SYSENTER_stack, %ecx
jb .Ldebug_from_sysenter_stack
@ -986,7 +986,7 @@ ENTRY(nmi)
/* Are we currently on the SYSENTER stack? */
movl PER_CPU_VAR(cpu_entry_area), %ecx
addl $CPU_ENTRY_AREA_tss + CPU_TSS_SYSENTER_stack + SIZEOF_SYSENTER_stack, %ecx
addl $CPU_ENTRY_AREA_tss + TSS_STRUCT_SYSENTER_stack + SIZEOF_SYSENTER_stack, %ecx
subl %eax, %ecx /* ecx = (end of SYSENTER_stack) - esp */
cmpl $SIZEOF_SYSENTER_stack, %ecx
jb .Lnmi_from_sysenter_stack

2
arch/x86/entry/entry_64.S
View File

@ -154,7 +154,7 @@ END(native_usergs_sysret64)
_entry_trampoline - CPU_ENTRY_AREA_entry_trampoline(%rip)
/* The top word of the SYSENTER stack is hot and is usable as scratch space. */
#define RSP_SCRATCH CPU_ENTRY_AREA_tss + CPU_TSS_SYSENTER_stack + \
#define RSP_SCRATCH CPU_ENTRY_AREA_tss + TSS_STRUCT_SYSENTER_stack + \
SIZEOF_SYSENTER_stack - 8 + CPU_ENTRY_AREA
ENTRY(entry_SYSCALL_64_trampoline)

5
arch/x86/include/asm/fixmap.h
View File

@ -245,5 +245,10 @@ static inline struct cpu_entry_area *get_cpu_entry_area(int cpu)
return (struct cpu_entry_area *)__fix_to_virt(__get_cpu_entry_area_page_index(cpu, 0));
}
static inline struct SYSENTER_stack *cpu_SYSENTER_stack(int cpu)
{
return &get_cpu_entry_area(cpu)->tss.SYSENTER_stack;
}
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_X86_FIXMAP_H */

6
arch/x86/include/asm/processor.h
View File

@ -336,12 +336,16 @@ struct x86_hw_tss {
#define IO_BITMAP_OFFSET (offsetof(struct tss_struct, io_bitmap) - offsetof(struct tss_struct, x86_tss))
#define INVALID_IO_BITMAP_OFFSET 0x8000
struct SYSENTER_stack {
unsigned long words[64];
};
struct tss_struct {
/*
* Space for the temporary SYSENTER stack, used for SYSENTER
* and the entry trampoline as well.
*/
unsigned long SYSENTER_stack[64];
struct SYSENTER_stack SYSENTER_stack;
/*
* The fixed hardware portion. This must not cross a page boundary

6
arch/x86/kernel/asm-offsets.c
View File

@ -94,10 +94,8 @@ void common(void) {
BLANK();
DEFINE(PTREGS_SIZE, sizeof(struct pt_regs));
/* Offset from cpu_tss to SYSENTER_stack */
OFFSET(CPU_TSS_SYSENTER_stack, tss_struct, SYSENTER_stack);
/* Size of SYSENTER_stack */
DEFINE(SIZEOF_SYSENTER_stack, sizeof(((struct tss_struct *)0)->SYSENTER_stack));
OFFSET(TSS_STRUCT_SYSENTER_stack, tss_struct, SYSENTER_stack);
DEFINE(SIZEOF_SYSENTER_stack, sizeof(struct SYSENTER_stack));
/* Layout info for cpu_entry_area */
OFFSET(CPU_ENTRY_AREA_tss, cpu_entry_area, tss);

14
arch/x86/kernel/cpu/common.c
View File

@ -1314,12 +1314,7 @@ void enable_sep_cpu(void)
tss->x86_tss.ss1 = __KERNEL_CS;
wrmsr(MSR_IA32_SYSENTER_CS, tss->x86_tss.ss1, 0);
wrmsr(MSR_IA32_SYSENTER_ESP,
(unsigned long)&get_cpu_entry_area(cpu)->tss +
offsetofend(struct tss_struct, SYSENTER_stack),
0);
wrmsr(MSR_IA32_SYSENTER_ESP, (unsigned long)(cpu_SYSENTER_stack(cpu) + 1), 0);
wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long)entry_SYSENTER_32, 0);
put_cpu();
@ -1436,9 +1431,7 @@ void syscall_init(void)
* AMD doesn't allow SYSENTER in long mode (either 32- or 64-bit).
*/
wrmsrl_safe(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);
wrmsrl_safe(MSR_IA32_SYSENTER_ESP,
(unsigned long)&get_cpu_entry_area(cpu)->tss +
offsetofend(struct tss_struct, SYSENTER_stack));
wrmsrl_safe(MSR_IA32_SYSENTER_ESP, (unsigned long)(cpu_SYSENTER_stack(cpu) + 1));
wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (u64)entry_SYSENTER_compat);
#else
wrmsrl(MSR_CSTAR, (unsigned long)ignore_sysret);
@ -1653,8 +1646,7 @@ void cpu_init(void)
*/
set_tss_desc(cpu, &get_cpu_entry_area(cpu)->tss.x86_tss);
load_TR_desc();
load_sp0((unsigned long)&get_cpu_entry_area(cpu)->tss +
offsetofend(struct tss_struct, SYSENTER_stack));
load_sp0((unsigned long)(cpu_SYSENTER_stack(cpu) + 1));
load_mm_ldt(&init_mm);

7
arch/x86/kernel/dumpstack.c
View File

@ -45,11 +45,10 @@ bool in_task_stack(unsigned long *stack, struct task_struct *task,
bool in_sysenter_stack(unsigned long *stack, struct stack_info *info)
{
int cpu = smp_processor_id();
struct tss_struct *tss = &get_cpu_entry_area(cpu)->tss;
struct SYSENTER_stack *ss = cpu_SYSENTER_stack(smp_processor_id());
void *begin = &tss->SYSENTER_stack;
void *end = (void *)&tss->SYSENTER_stack + sizeof(tss->SYSENTER_stack);
void *begin = ss;
void *end = ss + 1;
if ((void *)stack < begin || (void *)stack >= end)
return false;