Re: [Xen-devel] [PATCH 03/13] x86/paravirt: Convert native patch assembly code strings to macros

[Juergen Gross <jgross@xxxxxxxx>]

On 04/10/17 17:58, Josh Poimboeuf wrote:
> Convert the hard-coded native patch assembly code strings to macros to
> facilitate sharing common code between 32-bit and 64-bit.
> 
> These macros will also be used by a future patch which requires the GCC
> extended asm syntax of two '%' characters instead of one when specifying
> a register name.
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>

Mind adding another patch to merge the now nearly identical
paravirt_patch_32.c and paravirt_patch_64.c either into paravirt.c
or paravirt_patch.c? This would require only very few #ifdef.


Juergen

> ---
>  arch/x86/include/asm/special_insns.h | 24 ++++++++++++++++++++++++
>  arch/x86/kernel/paravirt_patch_32.c  | 21 +++++++++++----------
>  arch/x86/kernel/paravirt_patch_64.c  | 29 +++++++++++++++--------------
>  3 files changed, 50 insertions(+), 24 deletions(-)
> 
> diff --git a/arch/x86/include/asm/special_insns.h 
> b/arch/x86/include/asm/special_insns.h
> index ac402c6fc24b..0549c5f2c1b3 100644
> --- a/arch/x86/include/asm/special_insns.h
> +++ b/arch/x86/include/asm/special_insns.h
> @@ -6,6 +6,30 @@
>  
>  #include <asm/nops.h>
>  
> +#ifdef CONFIG_X86_64
> +# define _REG_ARG1                   "%rdi"
> +# define NATIVE_IDENTITY_32          "mov %edi, %eax"
> +# define NATIVE_USERGS_SYSRET64              "swapgs; sysretq"
> +#else
> +# define _REG_ARG1                   "%eax"
> +#endif
> +
> +#define _REG_RET                     "%" _ASM_AX
> +
> +#define NATIVE_ZERO                  "xor " _REG_ARG1 ", " _REG_ARG1
> +#define NATIVE_IDENTITY                      "mov " _REG_ARG1 ", " _REG_RET
> +#define NATIVE_SAVE_FL                       "pushf; pop " _REG_RET
> +#define NATIVE_RESTORE_FL            "push " _REG_ARG1 "; popf"
> +#define NATIVE_IRQ_DISABLE           "cli"
> +#define NATIVE_IRQ_ENABLE            "sti"
> +#define NATIVE_READ_CR2                      "mov %cr2, " _REG_RET
> +#define NATIVE_READ_CR3                      "mov %cr3, " _REG_RET
> +#define NATIVE_WRITE_CR3             "mov " _REG_ARG1 ", %cr3"
> +#define NATIVE_FLUSH_TLB_SINGLE              "invlpg (" _REG_ARG1 ")"
> +#define NATIVE_SWAPGS                        "swapgs"
> +#define NATIVE_IRET                  "iret"
> +#define NATIVE_QUEUED_SPIN_UNLOCK    "movb $0, (" _REG_ARG1 ")"
> +
>  /*
>   * Volatile isn't enough to prevent the compiler from reordering the
>   * read/write functions for the control registers and messing everything up.
> diff --git a/arch/x86/kernel/paravirt_patch_32.c 
> b/arch/x86/kernel/paravirt_patch_32.c
> index 553acbbb4d32..c9c6106ae714 100644
> --- a/arch/x86/kernel/paravirt_patch_32.c
> +++ b/arch/x86/kernel/paravirt_patch_32.c
> @@ -1,17 +1,18 @@
>  #include <asm/paravirt.h>
> +#include <asm/special_insns.h>
>  
> -DEF_NATIVE(pv_irq_ops, irq_disable, "cli");
> -DEF_NATIVE(pv_irq_ops, irq_enable, "sti");
> -DEF_NATIVE(pv_irq_ops, restore_fl, "push %eax; popf");
> -DEF_NATIVE(pv_irq_ops, save_fl, "pushf; pop %eax");
> -DEF_NATIVE(pv_cpu_ops, iret, "iret");
> -DEF_NATIVE(pv_mmu_ops, read_cr2, "mov %cr2, %eax");
> -DEF_NATIVE(pv_mmu_ops, write_cr3, "mov %eax, %cr3");
> -DEF_NATIVE(pv_mmu_ops, read_cr3, "mov %cr3, %eax");
> +DEF_NATIVE(pv_irq_ops,       save_fl,                NATIVE_SAVE_FL);
> +DEF_NATIVE(pv_irq_ops,       restore_fl,             NATIVE_RESTORE_FL);
> +DEF_NATIVE(pv_irq_ops,       irq_disable,            NATIVE_IRQ_DISABLE);
> +DEF_NATIVE(pv_irq_ops,       irq_enable,             NATIVE_IRQ_ENABLE);
> +DEF_NATIVE(pv_cpu_ops,       iret,                   NATIVE_IRET);
> +DEF_NATIVE(pv_mmu_ops,       read_cr2,               NATIVE_READ_CR2);
> +DEF_NATIVE(pv_mmu_ops,       read_cr3,               NATIVE_READ_CR3);
> +DEF_NATIVE(pv_mmu_ops,       write_cr3,              NATIVE_WRITE_CR3);
>  
>  #if defined(CONFIG_PARAVIRT_SPINLOCKS)
> -DEF_NATIVE(pv_lock_ops, queued_spin_unlock, "movb $0, (%eax)");
> -DEF_NATIVE(pv_lock_ops, vcpu_is_preempted, "xor %eax, %eax");
> +DEF_NATIVE(pv_lock_ops,      queued_spin_unlock,     
> NATIVE_QUEUED_SPIN_UNLOCK);
> +DEF_NATIVE(pv_lock_ops,      vcpu_is_preempted,      NATIVE_ZERO);
>  #endif
>  
>  unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len)
> diff --git a/arch/x86/kernel/paravirt_patch_64.c 
> b/arch/x86/kernel/paravirt_patch_64.c
> index 0a1ba3f80cbf..0aa232edd670 100644
> --- a/arch/x86/kernel/paravirt_patch_64.c
> +++ b/arch/x86/kernel/paravirt_patch_64.c
> @@ -1,25 +1,26 @@
>  #include <asm/paravirt.h>
>  #include <asm/asm-offsets.h>
> +#include <asm/special_insns.h>
>  #include <linux/stringify.h>
>  
> -DEF_NATIVE(pv_irq_ops, irq_disable, "cli");
> -DEF_NATIVE(pv_irq_ops, irq_enable, "sti");
> -DEF_NATIVE(pv_irq_ops, restore_fl, "pushq %rdi; popfq");
> -DEF_NATIVE(pv_irq_ops, save_fl, "pushfq; popq %rax");
> -DEF_NATIVE(pv_mmu_ops, read_cr2, "movq %cr2, %rax");
> -DEF_NATIVE(pv_mmu_ops, read_cr3, "movq %cr3, %rax");
> -DEF_NATIVE(pv_mmu_ops, write_cr3, "movq %rdi, %cr3");
> -DEF_NATIVE(pv_mmu_ops, flush_tlb_single, "invlpg (%rdi)");
> +DEF_NATIVE(pv_irq_ops,       save_fl,                NATIVE_SAVE_FL);
> +DEF_NATIVE(pv_irq_ops,       restore_fl,             NATIVE_RESTORE_FL);
> +DEF_NATIVE(pv_irq_ops,       irq_disable,            NATIVE_IRQ_DISABLE);
> +DEF_NATIVE(pv_irq_ops,       irq_enable,             NATIVE_IRQ_ENABLE);
> +DEF_NATIVE(pv_mmu_ops,       read_cr2,               NATIVE_READ_CR2);
> +DEF_NATIVE(pv_mmu_ops,       read_cr3,               NATIVE_READ_CR3);
> +DEF_NATIVE(pv_mmu_ops,       write_cr3,              NATIVE_WRITE_CR3);
> +DEF_NATIVE(pv_mmu_ops,       flush_tlb_single,       
> NATIVE_FLUSH_TLB_SINGLE);
>  
> -DEF_NATIVE(pv_cpu_ops, usergs_sysret64, "swapgs; sysretq");
> -DEF_NATIVE(pv_cpu_ops, swapgs, "swapgs");
> +DEF_NATIVE(pv_cpu_ops,       usergs_sysret64,        NATIVE_USERGS_SYSRET64);
> +DEF_NATIVE(pv_cpu_ops,       swapgs,                 NATIVE_SWAPGS);
>  
> -DEF_NATIVE(, mov32, "mov %edi, %eax");
> -DEF_NATIVE(, mov64, "mov %rdi, %rax");
> +DEF_NATIVE(,         mov32,                  NATIVE_IDENTITY_32);
> +DEF_NATIVE(,         mov64,                  NATIVE_IDENTITY);
>  
>  #if defined(CONFIG_PARAVIRT_SPINLOCKS)
> -DEF_NATIVE(pv_lock_ops, queued_spin_unlock, "movb $0, (%rdi)");
> -DEF_NATIVE(pv_lock_ops, vcpu_is_preempted, "xor %rax, %rax");
> +DEF_NATIVE(pv_lock_ops,      queued_spin_unlock,     
> NATIVE_QUEUED_SPIN_UNLOCK);
> +DEF_NATIVE(pv_lock_ops,      vcpu_is_preempted,      NATIVE_ZERO);
>  #endif
>  
>  unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len)
> 


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