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    Subject[PATCH 4.14 095/159] x86/entry: Clean up the SYSENTER_stack code
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Andy Lutomirski <luto@kernel.org>

    commit 0f9a48100fba3f189724ae88a450c2261bf91c80 upstream.

    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>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/entry/entry_32.S | 4 ++--
    arch/x86/entry/entry_64.S | 2 +-
    arch/x86/include/asm/fixmap.h | 5 +++++
    arch/x86/include/asm/processor.h | 6 +++++-
    arch/x86/kernel/asm-offsets.c | 6 ++----
    arch/x86/kernel/cpu/common.c | 14 +++-----------
    arch/x86/kernel/dumpstack.c | 7 +++----
    7 files changed, 21 insertions(+), 23 deletions(-)

    --- 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
    --- 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)
    --- 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
    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 */
    --- 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
    --- 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);
    --- 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);

    --- a/arch/x86/kernel/dumpstack.c
    +++ b/arch/x86/kernel/dumpstack.c
    @@ -45,11 +45,10 @@ bool in_task_stack(unsigned long *stack,

    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;

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