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From: Aaron Lewis <aaronlewis@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, jmattson@google.com, zxwang42@gmail.com,
	marcorr@google.com, seanjc@google.com, jroedel@suse.de,
	varad.gautam@suse.com
Subject: Re: [PATCH kvm-unit-tests 7/9] x86: get rid of ring0stacktop
Date: Thu, 21 Oct 2021 23:08:01 +0000	[thread overview]
Message-ID: <CAAAPnDHGEJP8Ss2M3KxVHT=MnHrbb-3=RAdpQVXzKyx9KWpRvw@mail.gmail.com> (raw)
In-Reply-To: <20211021114910.1347278-8-pbonzini@redhat.com>

> --- a/lib/x86/usermode.c
> +++ b/lib/x86/usermode.c
> @@ -47,8 +47,8 @@ uint64_t run_in_user(usermode_func func, unsigned int fault_vector,
>         }
>
>         asm volatile (
> -                       /* Backing Up Stack in rdi */
> -                       "mov %%rsp, %%rdi\n\t"
> +                       /* Prepare kernel SP for exception handlers */
> +                       "mov %%rsp, %[rsp0]\n\t"
>                         /* Load user_ds to DS and ES */
>                         "mov %[user_ds], %%ax\n\t"
>                         "mov %%ax, %%ds\n\t"
> @@ -92,9 +92,10 @@ uint64_t run_in_user(usermode_func func, unsigned int fault_vector,
>                         "int %[kernel_entry_vector]\n\t"
>                         /* Kernel Mode */
>                         "ret_to_kernel:\n\t"
> -                       "mov %%rdi, %%rsp\n\t"
> +                       "mov %[rsp0], %%rsp\n\t"
>                         :
> -                       "+a"(rax)
> +                       "+a"(rax),
> +                       [rsp0]"=m"(tss.rsp0),
>                         :

The compiler didn't like the comma:
-                       [rsp0]"=m"(tss.rsp0),
+                       [rsp0]"=m"(tss.rsp0)

>                         [arg1]"m"(arg1),
>                         [arg2]"m"(arg2),

> --- a/x86/umip.c
> +++ b/x86/umip.c
> @@ -124,7 +124,7 @@ static noinline int do_ring3(void (*fn)(const char *), const char *arg)
>                   "mov %%dx, %%es\n\t"
>                   "mov %%dx, %%fs\n\t"
>                   "mov %%dx, %%gs\n\t"
> -                 "mov %%" R "sp, %%" R "cx\n\t"
> +                 "mov %%" R "sp, %[sp0]\n\t" /* kernel sp for exception handlers */
>                   "push" W " %%" R "dx \n\t"
>                   "lea %[user_stack_top], %%" R "dx \n\t"
>                   "push" W " %%" R "dx \n\t"
> @@ -133,8 +133,6 @@ static noinline int do_ring3(void (*fn)(const char *), const char *arg)
>                   "push" W " $1f \n\t"
>                   "iret" W "\n"
>                   "1: \n\t"
> -                 "push %%" R "cx\n\t"   /* save kernel SP */
> -
>  #ifndef __x86_64__
>                   "push %[arg]\n\t"
>  #endif
> @@ -142,13 +140,15 @@ static noinline int do_ring3(void (*fn)(const char *), const char *arg)
>  #ifndef __x86_64__
>                   "pop %%ecx\n\t"
>  #endif
> -
> -                 "pop %%" R "cx\n\t"
>                   "mov $1f, %%" R "dx\n\t"
>                   "int %[kernel_entry_vector]\n\t"
>                   ".section .text.entry \n\t"
>                   "kernel_entry: \n\t"
> -                 "mov %%" R "cx, %%" R "sp \n\t"
> +#ifdef __x86_64__
> +                 "mov %[sp0], %%" R "sp\n\t"
> +#else
> +                 "add $(5 * " S "), %%esp\n\t"
> +#endif
>                   "mov %[kernel_ds], %%cx\n\t"
>                   "mov %%cx, %%ds\n\t"
>                   "mov %%cx, %%es\n\t"
> @@ -157,7 +157,12 @@ static noinline int do_ring3(void (*fn)(const char *), const char *arg)
>                   "jmp *%%" R "dx \n\t"
>                   ".section .text\n\t"
>                   "1:\n\t"
> -                 : [ret] "=&a" (ret)
> +                 : [ret] "=&a" (ret),
> +#ifdef __x86_64__
> +                   [sp0] "=m" (tss.rsp0),
> +#else
> +                   [sp0] "=m" (tss.esp0),
> +#endif
>                   : [user_ds] "i" (USER_DS),

Same here:
-                   [sp0] "=m" (tss.rsp0),
-                   [sp0] "=m" (tss.esp0),
+                   [sp0] "=m" (tss.rsp0)
+                   [sp0] "=m" (tss.esp0)

>                     [user_cs] "i" (USER_CS),
>                     [user_stack_top]"m"(user_stack[sizeof(user_stack) -
> --
> 2.27.0
>
>

  reply	other threads:[~2021-10-21 23:08 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-21 11:49 [PATCH v3 kvm-unit-tests 0/8] x86: Move IDT, GDT and TSS to C code Paolo Bonzini
2021-10-21 11:49 ` [PATCH kvm-unit-tests 1/9] x86: cleanup handling of 16-byte GDT descriptors Paolo Bonzini
2021-11-29 21:46   ` Marc Orr
2021-11-30 10:55     ` Paolo Bonzini
2021-11-30 17:22       ` Marc Orr
2021-11-30 17:26         ` Paolo Bonzini
2021-10-21 11:49 ` [PATCH kvm-unit-tests 2/9] x86: fix call to set_gdt_entry Paolo Bonzini
2021-10-21 11:49 ` [PATCH kvm-unit-tests 3/9] unify field names and definitions for GDT descriptors Paolo Bonzini
2021-10-21 11:49 ` [PATCH kvm-unit-tests 4/9] replace tss_descr global with a function Paolo Bonzini
2021-10-21 11:49 ` [PATCH kvm-unit-tests 5/9] x86: Move IDT to desc.c Paolo Bonzini
2021-10-21 11:49 ` [PATCH kvm-unit-tests 6/9] x86: unify name of 32-bit and 64-bit GDT Paolo Bonzini
2021-10-21 11:49 ` [PATCH kvm-unit-tests 7/9] x86: get rid of ring0stacktop Paolo Bonzini
2021-10-21 23:08   ` Aaron Lewis [this message]
2021-10-21 11:49 ` [PATCH kvm-unit-tests 8/9] x86: Move 64-bit GDT and TSS to desc.c Paolo Bonzini
2021-10-21 11:49 ` [PATCH kvm-unit-tests 9/9] x86: Move 32-bit " Paolo Bonzini
2021-10-21 14:37 ` [PATCH v3 kvm-unit-tests 0/8] x86: Move IDT, GDT and TSS to C code Paolo Bonzini

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