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    Subject[PATCH 08/12] x86-64: Move oldrsp from PDA to per-cpu.
    Date
    From: Brian Gerst <brgerst@gmail.com>

    tj: * in asm-offsets_64.c, pda.h inclusion shouldn't be removed as pda
    is still referenced in the file
    * s/oldrsp/old_rsp/

    Signed-off-by: Brian Gerst <brgerst@gmail.com>
    Signed-off-by: Tejun Heo <tj@kernel.org>
    ---
    arch/x86/include/asm/pda.h | 2 +-
    arch/x86/kernel/asm-offsets_64.c | 1 -
    arch/x86/kernel/entry_64.S | 10 +++++-----
    arch/x86/kernel/process_64.c | 8 +++++---
    arch/x86/xen/xen-asm_64.S | 8 ++++----
    5 files changed, 15 insertions(+), 14 deletions(-)

    diff --git a/arch/x86/include/asm/pda.h b/arch/x86/include/asm/pda.h
    index 4d28ffb..ae23deb 100644
    --- a/arch/x86/include/asm/pda.h
    +++ b/arch/x86/include/asm/pda.h
    @@ -14,7 +14,7 @@ struct x8664_pda {
    unsigned long unused1;
    unsigned long unused2;
    unsigned long unused3;
    - unsigned long oldrsp; /* 24 user rsp for system call */
    + unsigned long unused4;
    int irqcount; /* 32 Irq nesting counter. Starts -1 */
    unsigned int unused6; /* 36 was cpunumber */
    #ifdef CONFIG_CC_STACKPROTECTOR
    diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c
    index cafff5f..afda6de 100644
    --- a/arch/x86/kernel/asm-offsets_64.c
    +++ b/arch/x86/kernel/asm-offsets_64.c
    @@ -49,7 +49,6 @@ int main(void)
    BLANK();
    #undef ENTRY
    #define ENTRY(entry) DEFINE(pda_ ## entry, offsetof(struct x8664_pda, entry))
    - ENTRY(oldrsp);
    ENTRY(irqcount);
    DEFINE(pda_size, sizeof(struct x8664_pda));
    BLANK();
    diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
    index 0dd4585..7c27da4 100644
    --- a/arch/x86/kernel/entry_64.S
    +++ b/arch/x86/kernel/entry_64.S
    @@ -210,7 +210,7 @@ ENTRY(native_usergs_sysret64)

    /* %rsp:at FRAMEEND */
    .macro FIXUP_TOP_OF_STACK tmp offset=0
    - movq %gs:pda_oldrsp,\tmp
    + movq PER_CPU_VAR(old_rsp),\tmp
    movq \tmp,RSP+\offset(%rsp)
    movq $__USER_DS,SS+\offset(%rsp)
    movq $__USER_CS,CS+\offset(%rsp)
    @@ -221,7 +221,7 @@ ENTRY(native_usergs_sysret64)

    .macro RESTORE_TOP_OF_STACK tmp offset=0
    movq RSP+\offset(%rsp),\tmp
    - movq \tmp,%gs:pda_oldrsp
    + movq \tmp,PER_CPU_VAR(old_rsp)
    movq EFLAGS+\offset(%rsp),\tmp
    movq \tmp,R11+\offset(%rsp)
    .endm
    @@ -479,7 +479,7 @@ ENTRY(system_call)
    */
    ENTRY(system_call_after_swapgs)

    - movq %rsp,%gs:pda_oldrsp
    + movq %rsp,PER_CPU_VAR(old_rsp)
    movq PER_CPU_VAR(kernel_stack),%rsp
    /*
    * No need to follow this irqs off/on section - it's straight
    @@ -523,7 +523,7 @@ sysret_check:
    CFI_REGISTER rip,rcx
    RESTORE_ARGS 0,-ARG_SKIP,1
    /*CFI_REGISTER rflags,r11*/
    - movq %gs:pda_oldrsp, %rsp
    + movq PER_CPU_VAR(old_rsp), %rsp
    USERGS_SYSRET64

    CFI_RESTORE_STATE
    @@ -833,7 +833,7 @@ common_interrupt:
    XCPT_FRAME
    addq $-0x80,(%rsp) /* Adjust vector to [-256,-1] range */
    interrupt do_IRQ
    - /* 0(%rsp): oldrsp-ARGOFFSET */
    + /* 0(%rsp): old_rsp-ARGOFFSET */
    ret_from_intr:
    DISABLE_INTERRUPTS(CLBR_NONE)
    TRACE_IRQS_OFF
    diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
    index 6c5f576..4801289 100644
    --- a/arch/x86/kernel/process_64.c
    +++ b/arch/x86/kernel/process_64.c
    @@ -60,6 +60,8 @@ asmlinkage extern void ret_from_fork(void);
    DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
    EXPORT_PER_CPU_SYMBOL(current_task);

    +DEFINE_PER_CPU(unsigned long, old_rsp);
    +
    unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;

    static ATOMIC_NOTIFIER_HEAD(idle_notifier);
    @@ -395,7 +397,7 @@ start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
    load_gs_index(0);
    regs->ip = new_ip;
    regs->sp = new_sp;
    - write_pda(oldrsp, new_sp);
    + percpu_write(old_rsp, new_sp);
    regs->cs = __USER_CS;
    regs->ss = __USER_DS;
    regs->flags = 0x200;
    @@ -616,8 +618,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
    /*
    * Switch the PDA and FPU contexts.
    */
    - prev->usersp = read_pda(oldrsp);
    - write_pda(oldrsp, next->usersp);
    + prev->usersp = percpu_read(old_rsp);
    + percpu_write(old_rsp, next->usersp);
    percpu_write(current_task, next_p);

    percpu_write(kernel_stack,
    diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
    index 5a23e89..d6fc51f 100644
    --- a/arch/x86/xen/xen-asm_64.S
    +++ b/arch/x86/xen/xen-asm_64.S
    @@ -194,11 +194,11 @@ RELOC(xen_sysexit, 1b+1)
    ENTRY(xen_sysret64)
    /* We're already on the usermode stack at this point, but still
    with the kernel gs, so we can easily switch back */
    - movq %rsp, %gs:pda_oldrsp
    + movq %rsp, PER_CPU_VAR(old_rsp)
    movq PER_CPU_VAR(kernel_stack),%rsp

    pushq $__USER_DS
    - pushq %gs:pda_oldrsp
    + pushq PER_CPU_VAR(old_rsp)
    pushq %r11
    pushq $__USER_CS
    pushq %rcx
    @@ -211,11 +211,11 @@ RELOC(xen_sysret64, 1b+1)
    ENTRY(xen_sysret32)
    /* We're already on the usermode stack at this point, but still
    with the kernel gs, so we can easily switch back */
    - movq %rsp, %gs:pda_oldrsp
    + movq %rsp, PER_CPU_VAR(old_rsp)
    movq PER_CPU_VAR(kernel_stack), %rsp

    pushq $__USER32_DS
    - pushq %gs:pda_oldrsp
    + pushq PER_CPU_VAR(old_rsp)
    pushq %r11
    pushq $__USER32_CS
    pushq %rcx
    --
    1.6.0.2


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