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Message-ID: <20070721033813.GP3672@sequoia.sous-sol.org>
Date: Fri, 20 Jul 2007 20:38:13 -0700
From: Chris Wright <chrisw@...s-sol.org>
To: Glauber de Oliveira Costa <gcosta@...hat.com>
Cc: linux-kernel@...r.kernel.org, ak@...e.de,
akpm@...ux-foundation.org, rostedt@...dmis.org, chrisw@...s-sol.org
Subject: Re: [PATCH] Use descriptor's functions instead of inline assembly
* Glauber de Oliveira Costa (gcosta@...hat.com) wrote:
> This patch provides a new set of functions for managing the descriptor
> tables that can be used instead of putting the raw assembly in .c files.
Looks alright, some cleanups below
> Remodeling of store_tr() suggested by Frederik Deweerdt.
>
> Signed-off-by: Glauber de Oliveira Costa <gcosta@...hat.com>
>
> diff --git a/arch/x86_64/kernel/head64.c b/arch/x86_64/kernel/head64.c
> index 6c34bdd..dde41d7 100644
> --- a/arch/x86_64/kernel/head64.c
> +++ b/arch/x86_64/kernel/head64.c
> @@ -70,7 +70,7 @@ void __init x86_64_start_kernel(char * real_mode_data)
>
> for (i = 0; i < IDT_ENTRIES; i++)
> set_intr_gate(i, early_idt_handler);
> - asm volatile("lidt %0" :: "m" (idt_descr));
> + load_idt((const struct desc_ptr *)&idt_descr);
No need for extra casting
> early_printk("Kernel alive\n");
>
> diff --git a/arch/x86_64/kernel/reboot.c b/arch/x86_64/kernel/reboot.c
> index 7503068..7c50a12 100644
> --- a/arch/x86_64/kernel/reboot.c
> +++ b/arch/x86_64/kernel/reboot.c
> @@ -11,6 +11,7 @@
> #include <linux/sched.h>
> #include <asm/io.h>
> #include <asm/delay.h>
> +#include <asm/desc.h>
> #include <asm/hw_irq.h>
> #include <asm/system.h>
> #include <asm/pgtable.h>
> @@ -132,7 +133,7 @@ void machine_emergency_restart(void)
> }
>
> case BOOT_TRIPLE:
> - __asm__ __volatile__("lidt (%0)": :"r" (&no_idt));
> + load_idt((const struct desc_ptr *)&no_idt);
same here, plus opportunity for cleanup
> __asm__ __volatile__("int3");
>
> reboot_type = BOOT_KBD;
> diff --git a/arch/x86_64/kernel/setup64.c b/arch/x86_64/kernel/setup64.c
> index 1200aaa..fef7290 100644
> --- a/arch/x86_64/kernel/setup64.c
> +++ b/arch/x86_64/kernel/setup64.c
> @@ -224,8 +224,8 @@ void __cpuinit cpu_init (void)
> memcpy(cpu_gdt(cpu), cpu_gdt_table, GDT_SIZE);
>
> cpu_gdt_descr[cpu].size = GDT_SIZE;
> - asm volatile("lgdt %0" :: "m" (cpu_gdt_descr[cpu]));
> - asm volatile("lidt %0" :: "m" (idt_descr));
> + load_gdt((const struct desc_ptr *)&cpu_gdt_descr[cpu]);
> + load_idt((const struct desc_ptr *)&idt_descr);
same here
> memset(me->thread.tls_array, 0, GDT_ENTRY_TLS_ENTRIES * 8);
> syscall_init();
> diff --git a/arch/x86_64/kernel/suspend.c b/arch/x86_64/kernel/suspend.c
> index b39d478..ddedadf 100644
> --- a/arch/x86_64/kernel/suspend.c
> +++ b/arch/x86_64/kernel/suspend.c
> @@ -32,9 +32,9 @@ void __save_processor_state(struct saved_context *ctxt)
> /*
> * descriptor tables
> */
> - asm volatile ("sgdt %0" : "=m" (ctxt->gdt_limit));
> - asm volatile ("sidt %0" : "=m" (ctxt->idt_limit));
> - asm volatile ("str %0" : "=m" (ctxt->tr));
> + store_gdt((struct desc_ptr *)&ctxt->gdt_limit);
> + store_idt((struct desc_ptr *)&ctxt->idt_limit);
same here, opportunity for cleanup
> + store_tr(ctxt->tr);
>
> /* XMM0..XMM15 should be handled by kernel_fpu_begin(). */
> /*
> @@ -91,8 +91,9 @@ void __restore_processor_state(struct saved_context *ctxt)
> * now restore the descriptor tables to their proper values
> * ltr is done i fix_processor_context().
> */
> - asm volatile ("lgdt %0" :: "m" (ctxt->gdt_limit));
> - asm volatile ("lidt %0" :: "m" (ctxt->idt_limit));
> + load_gdt((const struct desc_ptr *)&ctxt->gdt_limit);
> + load_idt((const struct desc_ptr *)&ctxt->idt_limit);
> +
>
> /*
> * segment registers
> diff --git a/include/asm-x86_64/desc.h b/include/asm-x86_64/desc.h
> index ac991b5..f2b0a6f 100644
> --- a/include/asm-x86_64/desc.h
> +++ b/include/asm-x86_64/desc.h
> @@ -20,6 +20,15 @@ extern struct desc_struct cpu_gdt_table[GDT_ENTRIES];
> #define load_LDT_desc() asm volatile("lldt %w0"::"r" (GDT_ENTRY_LDT*8))
> #define clear_LDT() asm volatile("lldt %w0"::"r" (0))
>
> +static inline unsigned long __store_tr(void)
> +{
> + unsigned long tr;
> + asm volatile ("str %w0":"=r" (tr));
> + return tr;
> +}
native_store_tr (although I've no objection to just fixing the interface)
Index: linus-2.6/arch/x86_64/kernel/head64.c
===================================================================
--- linus-2.6.orig/arch/x86_64/kernel/head64.c
+++ linus-2.6/arch/x86_64/kernel/head64.c
@@ -70,7 +70,7 @@ void __init x86_64_start_kernel(char * r
for (i = 0; i < IDT_ENTRIES; i++)
set_intr_gate(i, early_idt_handler);
- load_idt((const struct desc_ptr *)&idt_descr);
+ load_idt(&idt_descr);
early_printk("Kernel alive\n");
Index: linus-2.6/arch/x86_64/kernel/reboot.c
===================================================================
--- linus-2.6.orig/arch/x86_64/kernel/reboot.c
+++ linus-2.6/arch/x86_64/kernel/reboot.c
@@ -24,7 +24,7 @@
void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);
-static long no_idt[3];
+static struct desc_ptr no_idt;
static enum {
BOOT_TRIPLE = 't',
BOOT_KBD = 'k'
@@ -133,7 +133,7 @@ void machine_emergency_restart(void)
}
case BOOT_TRIPLE:
- load_idt((const struct desc_ptr *)&no_idt);
+ load_idt(&no_idt);
__asm__ __volatile__("int3");
reboot_type = BOOT_KBD;
Index: linus-2.6/arch/x86_64/kernel/setup64.c
===================================================================
--- linus-2.6.orig/arch/x86_64/kernel/setup64.c
+++ linus-2.6/arch/x86_64/kernel/setup64.c
@@ -224,8 +224,8 @@ void __cpuinit cpu_init (void)
memcpy(cpu_gdt(cpu), cpu_gdt_table, GDT_SIZE);
cpu_gdt_descr[cpu].size = GDT_SIZE;
- load_gdt((const struct desc_ptr *)&cpu_gdt_descr[cpu]);
- load_idt((const struct desc_ptr *)&idt_descr);
+ load_gdt(&cpu_gdt_descr[cpu]);
+ load_idt(&idt_descr);
memset(me->thread.tls_array, 0, GDT_ENTRY_TLS_ENTRIES * 8);
syscall_init();
Index: linus-2.6/arch/x86_64/kernel/suspend.c
===================================================================
--- linus-2.6.orig/arch/x86_64/kernel/suspend.c
+++ linus-2.6/arch/x86_64/kernel/suspend.c
@@ -32,8 +32,8 @@ void __save_processor_state(struct saved
/*
* descriptor tables
*/
- store_gdt((struct desc_ptr *)&ctxt->gdt_limit);
- store_idt((struct desc_ptr *)&ctxt->idt_limit);
+ store_gdt(&ctxt->gdt);
+ store_idt(&ctxt->idt);
store_tr(ctxt->tr);
/* XMM0..XMM15 should be handled by kernel_fpu_begin(). */
@@ -91,8 +91,8 @@ void __restore_processor_state(struct sa
* now restore the descriptor tables to their proper values
* ltr is done i fix_processor_context().
*/
- load_gdt((const struct desc_ptr *)&ctxt->gdt_limit);
- load_idt((const struct desc_ptr *)&ctxt->idt_limit);
+ load_gdt(&ctxt->gdt);
+ load_idt(&ctxt->idt);
/*
Index: linus-2.6/include/asm-x86_64/desc.h
===================================================================
--- linus-2.6.orig/include/asm-x86_64/desc.h
+++ linus-2.6/include/asm-x86_64/desc.h
@@ -20,14 +20,14 @@ extern struct desc_struct cpu_gdt_table[
#define load_LDT_desc() asm volatile("lldt %w0"::"r" (GDT_ENTRY_LDT*8))
#define clear_LDT() asm volatile("lldt %w0"::"r" (0))
-static inline unsigned long __store_tr(void)
+static inline unsigned long native_store_tr(void)
{
unsigned long tr;
asm volatile ("str %w0":"=r" (tr));
return tr;
}
-#define store_tr(tr) (tr) = __store_tr()
+#define store_tr(tr) (tr) = native_store_tr()
/*
* This is the ldt that every process will get unless we need
Index: linus-2.6/arch/x86_64/kernel/machine_kexec.c
===================================================================
--- linus-2.6.orig/arch/x86_64/kernel/machine_kexec.c
+++ linus-2.6/arch/x86_64/kernel/machine_kexec.c
@@ -119,11 +119,8 @@ static void set_idt(void *newidt, u16 li
/* x86-64 supports unaliged loads & stores */
curidt.size = limit;
curidt.address = (unsigned long)newidt;
-
- __asm__ __volatile__ (
- "lidtq %0\n"
- : : "m" (curidt)
- );
+
+ load_idt(&curidt);
};
@@ -135,10 +132,7 @@ static void set_gdt(void *newgdt, u16 li
curgdt.size = limit;
curgdt.address = (unsigned long)newgdt;
- __asm__ __volatile__ (
- "lgdtq %0\n"
- : : "m" (curgdt)
- );
+ load_gdt(&curgdt);
};
static void load_segments(void)
Index: linus-2.6/include/asm-x86_64/suspend.h
===================================================================
--- linus-2.6.orig/include/asm-x86_64/suspend.h
+++ linus-2.6/include/asm-x86_64/suspend.h
@@ -18,12 +18,8 @@ struct saved_context {
unsigned long gs_base, gs_kernel_base, fs_base;
unsigned long cr0, cr2, cr3, cr4, cr8;
unsigned long efer;
- u16 gdt_pad;
- u16 gdt_limit;
- unsigned long gdt_base;
- u16 idt_pad;
- u16 idt_limit;
- unsigned long idt_base;
+ struct desc_ptr gdt;
+ struct desc_ptr idt;
u16 ldt;
u16 tss;
unsigned long tr;
-
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