[PATCH] i386: inline assembler: cleanup and encapsulate descriptor and task register...

i386 inline assembler cleanup.

This change encapsulates descriptor and task register management.  Also,
it is possible to improve assembler generation in two cases; savesegment
may store the value in a register instead of a memory location, which
allows GCC to optimize stack variables into registers, and MOV MEM, SEG
is always a 16-bit write to memory, making the casting in math-emu
unnecessary.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/i386/kernel/cpu/common.c b/arch/i386/kernel/cpu/common.c
index 361f2e7ccb12274385902f12bb9cd7f159ffaee1..46ce9b248f5510088ca7fd1765fcfdd86ea44bd9 100644 (file)
--- a/arch/i386/kernel/cpu/common.c
+++ b/arch/i386/kernel/cpu/common.c
@@ -613,8 +613,8 @@ void __devinit cpu_init(void)
        memcpy(thread->tls_array, &per_cpu(cpu_gdt_table, cpu),
                GDT_ENTRY_TLS_ENTRIES * 8);
 
-       __asm__ __volatile__("lgdt %0" : : "m" (cpu_gdt_descr[cpu]));
-       __asm__ __volatile__("lidt %0" : : "m" (idt_descr));
+       load_gdt(&cpu_gdt_descr[cpu]);
+       load_idt(&idt_descr);
 
        /*
         * Delete NT

diff --git a/arch/i386/kernel/doublefault.c b/arch/i386/kernel/doublefault.c
index 789af3e9fb1fff597529ea62a80fc81a9fa2cc6c..5edb1d379add9d24bd353e2ade6c176d0a3cdca5 100644 (file)
--- a/arch/i386/kernel/doublefault.c
+++ b/arch/i386/kernel/doublefault.c
@@ -20,7 +20,7 @@ static void doublefault_fn(void)
        struct Xgt_desc_struct gdt_desc = {0, 0};
        unsigned long gdt, tss;
 
-       __asm__ __volatile__("sgdt %0": "=m" (gdt_desc): :"memory");
+       store_gdt(&gdt_desc);
        gdt = gdt_desc.address;
 
        printk("double fault, gdt at %08lx [%d bytes]\n", gdt, gdt_desc.size);

diff --git a/arch/i386/kernel/efi.c b/arch/i386/kernel/efi.c
index 921fdb15fc9be234282090e9a3616d084a61217f..ecad519fd395f6a17607c65737713f5aca26c3d3 100644 (file)
--- a/arch/i386/kernel/efi.c
+++ b/arch/i386/kernel/efi.c
@@ -104,8 +104,7 @@ static void efi_call_phys_prelog(void)
        local_flush_tlb();
 
        cpu_gdt_descr[0].address = __pa(cpu_gdt_descr[0].address);
-       __asm__ __volatile__("lgdt %0":"=m"
-                           (*(struct Xgt_desc_struct *) __pa(&cpu_gdt_descr[0])));
+       load_gdt((struct Xgt_desc_struct *) __pa(&cpu_gdt_descr[0]));
 }
 
 static void efi_call_phys_epilog(void)
@@ -114,7 +113,7 @@ static void efi_call_phys_epilog(void)
 
        cpu_gdt_descr[0].address =
                (unsigned long) __va(cpu_gdt_descr[0].address);
-       __asm__ __volatile__("lgdt %0":"=m"(cpu_gdt_descr));
+       load_gdt(&cpu_gdt_descr[0]);
        cr4 = read_cr4();
 
        if (cr4 & X86_CR4_PSE) {

diff --git a/arch/i386/kernel/reboot.c b/arch/i386/kernel/reboot.c
index c71fef31dc4797d891f10c5d8d257bbf11d73df7..1cbb9c0f47040d9eb430e738f81871ff18aeacee 100644 (file)
--- a/arch/i386/kernel/reboot.c
+++ b/arch/i386/kernel/reboot.c
@@ -13,6 +13,7 @@
 #include <linux/dmi.h>
 #include <asm/uaccess.h>
 #include <asm/apic.h>
+#include <asm/desc.h>
 #include "mach_reboot.h"
 #include <linux/reboot_fixups.h>
 
@@ -242,13 +243,13 @@ void machine_real_restart(unsigned char *code, int length)
 
        /* Set up the IDT for real mode. */
 
-       __asm__ __volatile__ ("lidt %0" : : "m" (real_mode_idt));
+       load_idt(&real_mode_idt);
 
        /* Set up a GDT from which we can load segment descriptors for real
           mode.  The GDT is not used in real mode; it is just needed here to
           prepare the descriptors. */
 
-       __asm__ __volatile__ ("lgdt %0" : : "m" (real_mode_gdt));
+       load_gdt(&real_mode_gdt);
 
        /* Load the data segment registers, and thus the descriptors ready for
           real mode.  The base address of each segment is 0x100, 16 times the
@@ -316,7 +317,7 @@ void machine_emergency_restart(void)
        if (!reboot_thru_bios) {
                if (efi_enabled) {
                        efi.reset_system(EFI_RESET_COLD, EFI_SUCCESS, 0, NULL);
-                       __asm__ __volatile__("lidt %0": :"m" (no_idt));
+                       load_idt(&no_idt);
                        __asm__ __volatile__("int3");
                }
                /* rebooting needs to touch the page at absolute addr 0 */
@@ -325,7 +326,7 @@ void machine_emergency_restart(void)
                        mach_reboot_fixups(); /* for board specific fixups */
                        mach_reboot();
                        /* That didn't work - force a triple fault.. */
-                       __asm__ __volatile__("lidt %0": :"m" (no_idt));
+                       load_idt(&no_idt);
                        __asm__ __volatile__("int3");
                }
        }

diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c
index 140e340569c67711fc83f3f54cf4139d64c701aa..7bcda6d69d87389387560ade09ae126dd5968f55 100644 (file)
--- a/arch/i386/kernel/signal.c
+++ b/arch/i386/kernel/signal.c
@@ -278,9 +278,9 @@ setup_sigcontext(struct sigcontext __user *sc, struct _fpstate __user *fpstate,
        int tmp, err = 0;
 
        tmp = 0;
-       __asm__("movl %%gs,%0" : "=r"(tmp): "0"(tmp));
+       savesegment(gs, tmp);
        err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
-       __asm__("movl %%fs,%0" : "=r"(tmp): "0"(tmp));
+       savesegment(fs, tmp);
        err |= __put_user(tmp, (unsigned int __user *)&sc->fs);
 
        err |= __put_user(regs->xes, (unsigned int __user *)&sc->es);

diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index cd2d5d5514fe0ffcdf78cadfbabdf5863ede040c..1144df0c48d695484365709dbad8df1badd34ff5 100644 (file)
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -1008,7 +1008,7 @@ void __init trap_init_f00f_bug(void)
         * it uses the read-only mapped virtual address.
         */
        idt_descr.address = fix_to_virt(FIX_F00F_IDT);
-       __asm__ __volatile__("lidt %0" : : "m" (idt_descr));
+       load_idt(&idt_descr);
 }
 #endif
 

diff --git a/arch/i386/kernel/vm86.c b/arch/i386/kernel/vm86.c
index 2daa06fb4a881575a1685d1cca62c0ef61a5233a..16b485009622a578e274c260cf975b3fd1a77f0e 100644 (file)
--- a/arch/i386/kernel/vm86.c
+++ b/arch/i386/kernel/vm86.c
@@ -294,8 +294,8 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk
  */
        info->regs32->eax = 0;
        tsk->thread.saved_esp0 = tsk->thread.esp0;
-       asm volatile("mov %%fs,%0":"=m" (tsk->thread.saved_fs));
-       asm volatile("mov %%gs,%0":"=m" (tsk->thread.saved_gs));
+       savesegment(fs, tsk->thread.saved_fs);
+       savesegment(gs, tsk->thread.saved_gs);
 
        tss = &per_cpu(init_tss, get_cpu());
        tsk->thread.esp0 = (unsigned long) &info->VM86_TSS_ESP0;

diff --git a/arch/i386/math-emu/get_address.c b/arch/i386/math-emu/get_address.c
index 91175738e94808a8aa5a988f1fe5183211fa58ca..9819b705efa422af8c3f1ee5652fa0649f606811 100644 (file)
--- a/arch/i386/math-emu/get_address.c
+++ b/arch/i386/math-emu/get_address.c
@@ -155,7 +155,6 @@ static long pm_address(u_char FPU_modrm, u_char segment,
 { 
   struct desc_struct descriptor;
   unsigned long base_address, limit, address, seg_top;
-  unsigned short selector;
 
   segment--;
 
@@ -173,17 +172,11 @@ static long pm_address(u_char FPU_modrm, u_char segment,
       /* fs and gs aren't used by the kernel, so they still have their
         user-space values. */
     case PREFIX_FS_-1:
-      /* The cast is needed here to get gcc 2.8.0 to use a 16 bit register
-        in the assembler statement. */
-
-      __asm__("mov %%fs,%0":"=r" (selector));
-      addr->selector = selector;
+      /* N.B. - movl %seg, mem is a 2 byte write regardless of prefix */
+      savesegment(fs, addr->selector);
       break;
     case PREFIX_GS_-1:
-      /* The cast is needed here to get gcc 2.8.0 to use a 16 bit register
-        in the assembler statement. */
-      __asm__("mov %%gs,%0":"=r" (selector));
-      addr->selector = selector;
+      savesegment(gs, addr->selector);
       break;
     default:
       addr->selector = PM_REG_(segment);

diff --git a/arch/i386/power/cpu.c b/arch/i386/power/cpu.c
index 4e19c43e09541bbbb3d429bdcbd1acd0556d3ea2..c7a6436aa938039ec9d4bcbb6b7c49d5bc2ebdcd 100644 (file)
--- a/arch/i386/power/cpu.c
+++ b/arch/i386/power/cpu.c
@@ -42,17 +42,17 @@ 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(&ctxt->gdt_limit);
+       store_idt(&ctxt->idt_limit);
+       store_tr(ctxt->tr);
 
        /*
         * segment registers
         */
-       asm volatile ("movw %%es, %0" : "=m" (ctxt->es));
-       asm volatile ("movw %%fs, %0" : "=m" (ctxt->fs));
-       asm volatile ("movw %%gs, %0" : "=m" (ctxt->gs));
-       asm volatile ("movw %%ss, %0" : "=m" (ctxt->ss));
+       savesegment(es, ctxt->es);
+       savesegment(fs, ctxt->fs);
+       savesegment(gs, ctxt->gs);
+       savesegment(ss, ctxt->ss);
 
        /*
         * control registers 
@@ -118,16 +118,16 @@ 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(&ctxt->gdt_limit);
+       load_idt(&ctxt->idt_limit);
 
        /*
         * segment registers
         */
-       asm volatile ("movw %0, %%es" :: "r" (ctxt->es));
-       asm volatile ("movw %0, %%fs" :: "r" (ctxt->fs));
-       asm volatile ("movw %0, %%gs" :: "r" (ctxt->gs));
-       asm volatile ("movw %0, %%ss" :: "r" (ctxt->ss));
+       loadsegment(es, ctxt->es);
+       loadsegment(fs, ctxt->fs);
+       loadsegment(gs, ctxt->gs);
+       loadsegment(ss, ctxt->ss);
 
        /*
         * sysenter MSRs

diff --git a/include/asm-i386/desc.h b/include/asm-i386/desc.h
index 11e67811a9901b5c6b31ef361dfb6d03667c3ca3..9a0b85a52e7181bc5146cf602695be66f383af03 100644 (file)
--- a/include/asm-i386/desc.h
+++ b/include/asm-i386/desc.h
@@ -30,6 +30,16 @@ extern struct Xgt_desc_struct idt_descr, cpu_gdt_descr[NR_CPUS];
 #define load_TR_desc() __asm__ __volatile__("ltr %%ax"::"a" (GDT_ENTRY_TSS*8))
 #define load_LDT_desc() __asm__ __volatile__("lldt %%ax"::"a" (GDT_ENTRY_LDT*8))
 
+#define load_gdt(dtr) __asm__ __volatile("lgdt %0"::"m" (*dtr))
+#define load_idt(dtr) __asm__ __volatile("lidt %0"::"m" (*dtr))
+#define load_tr(tr) __asm__ __volatile("ltr %0"::"mr" (tr))
+#define load_ldt(ldt) __asm__ __volatile("lldt %0"::"mr" (ldt))
+
+#define store_gdt(dtr) __asm__ ("sgdt %0":"=m" (*dtr))
+#define store_idt(dtr) __asm__ ("sidt %0":"=m" (*dtr))
+#define store_tr(tr) __asm__ ("str %0":"=mr" (tr))
+#define store_ldt(ldt) __asm__ ("sldt %0":"=mr" (ldt))
+
 /*
  * This is the ldt that every process will get unless we need
  * something other than this.

diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h
index 8048a5e018cd1953fb097e3531d0fea6cbc83254..37fd2f8c71963dc78153292459d62a0d6a9860d0 100644 (file)
--- a/include/asm-i386/system.h
+++ b/include/asm-i386/system.h
@@ -93,13 +93,13 @@ static inline unsigned long _get_base(char * addr)
                ".align 4\n\t"                  \
                ".long 1b,3b\n"                 \
                ".previous"                     \
-               : :"m" (value))
+               : :"rm" (value))
 
 /*
  * Save a segment register away
  */
 #define savesegment(seg, value) \
-       asm volatile("mov %%" #seg ",%0":"=m" (value))
+       asm volatile("mov %%" #seg ",%0":"=rm" (value))
 
 /*
  * Clear and set 'TS' bit respectively