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>

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 0ab316c468067357663529ce5c53c31a32b35f46..3629bcbf85a2dc440b213ab5456ed36ac86a7e62 100644 (file)
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -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

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 2582984ffb4b23f541d43c7a82e5c8907bb1fccf..575b184f377fe5504f2bd330ef6a852c5dd99ceb 100644 (file)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -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)

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index 451da7d9a5026829e060845b6962700b3bb8f8b8..cc5d98bdca37f101356aebe0b059372d4942438d 100644 (file)
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -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 */

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index d34ac13c586652a195774dd7957ded83574c6f5b..f933869470b89bd3dfc1f12f84fd3142509f427a 100644 (file)
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -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

diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 61b1af88ac0707fda38e86627be42a35c6e5bddf..46c0995344aaad688c326e7d664c5cee737918a2 100644 (file)
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -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);

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index fb01a8e5e9b7dfbbf880555c1db83984db51df06..3de7480e4f326720fe76586a57ec9914d1ebe66e 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -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);
 

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index ae1ce2e3f132603f0d638c6880dd63f62769a1a1..bbd6d986e2d0fc22b5b3c23c794ade410b9f9973 100644 (file)
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -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;