[PATCH 9/14] i386 / Typecheck and optimize base and limit accessors

From: zach
Date: Wed Aug 10 2005 - 23:57:42 EST

Found some stray descriptor table accessors that had non-optimal assembler
constraints. Use "q" to get word, high and low byte access without forcing
a specific register constraint. Add desc as a memory output operand.

Also, get_base was completely unused. Deprecate it.

The function get_limit is also unused, but I did not deprecate it; it could
be used in arch/i386/mm/fault.c.

Patch-base: 2.6.13-rc5-mm1
Patch-keys: i386 desc cleanup optimize
Signed-off-by: Zachary Amsden <zach@xxxxxxxxxx>
Index: linux-2.6.13/include/asm-i386/system.h
===================================================================
--- linux-2.6.13.orig/include/asm-i386/system.h 2005-08-09 20:17:14.000000000 -0700
+++ linux-2.6.13/include/asm-i386/system.h 2005-08-10 20:41:03.000000000 -0700
@@ -29,49 +29,39 @@
"2" (prev), "d" (next)); \
} while (0)

-#define _set_base(addr,base) do { unsigned long __pr; \
-__asm__ __volatile__ ("movw %%dx,%1\n\t" \
- "rorl $16,%%edx\n\t" \
- "movb %%dl,%2\n\t" \
- "movb %%dh,%3" \
- :"=&d" (__pr) \
- :"m" (*((addr)+2)), \
- "m" (*((addr)+4)), \
- "m" (*((addr)+7)), \
- "0" (base) \
- ); } while(0)
-
-#define _set_limit(addr,limit) do { unsigned long __lr; \
-__asm__ __volatile__ ("movw %%dx,%1\n\t" \
- "rorl $16,%%edx\n\t" \
- "movb %2,%%dh\n\t" \
- "andb $0xf0,%%dh\n\t" \
- "orb %%dh,%%dl\n\t" \
- "movb %%dl,%2" \
- :"=&d" (__lr) \
- :"m" (*(addr)), \
- "m" (*((addr)+6)), \
- "0" (limit) \
- ); } while(0)
+#define _set_base(desc,base) do { \
+ unsigned long __tmp; \
+ typecheck(struct desc_struct *, desc); \
+ asm volatile("movw %w5,%2\n\t" \
+ "rorl $16,%5\n\t" \
+ "movb %b5,%3\n\t" \
+ "movb %h5,%4" \
+ :"=m"(*(desc)), \
+ "=&q" (__tmp) \
+ :"m" (*((char *)(desc)+2)), \
+ "m" (*((char *)(desc)+4)), \
+ "m" (*((char *)(desc)+7)), \
+ "1" (base)); \
+} while(0)
+
+#define _set_limit(desc,limit) do { \
+ unsigned long __tmp; \
+ typecheck(struct desc_struct *, desc); \
+ asm volatile("movw %w4,%2\n\t" \
+ "rorl $16,%4\n\t" \
+ "movb %3,%h4\n\t" \
+ "andb $0xf0,%h4\n\t" \
+ "orb %h4,%b4\n\t" \
+ "movb %b4,%3" \
+ :"=m"(*(desc)), \
+ "=&q" (__tmp) \
+ :"m" (*(desc)), \
+ "m" (*((char *)(desc)+6)), \
+ "1" (limit)); \
+} while(0)

-#define set_base(ldt,base) _set_base( ((char *)&(ldt)) , (base) )
-#define set_limit(ldt,limit) _set_limit( ((char *)&(ldt)) , ((limit)-1)>>12 )
-
-static inline unsigned long _get_base(char * addr)
-{
- unsigned long __base;
- __asm__("movb %3,%%dh\n\t"
- "movb %2,%%dl\n\t"
- "shll $16,%%edx\n\t"
- "movw %1,%%dx"
- :"=&d" (__base)
- :"m" (*((addr)+2)),
- "m" (*((addr)+4)),
- "m" (*((addr)+7)));
- return __base;
-}
-
-#define get_base(ldt) _get_base( ((char *)&(ldt)) )
+#define set_base(desc,base) _set_base((desc), (base))
+#define set_limit(desc,limit) _set_limit((desc), ((limit)-1)>>12)

/*
* Load a segment. Fall back on loading the zero
Index: linux-2.6.13/arch/i386/kernel/apm.c
===================================================================
--- linux-2.6.13.orig/arch/i386/kernel/apm.c 2005-08-09 20:17:26.000000000 -0700
+++ linux-2.6.13/arch/i386/kernel/apm.c 2005-08-09 20:17:26.000000000 -0700
@@ -2291,40 +2291,40 @@
* This is for buggy BIOS's that refer to (real mode) segment 0x40
* even though they are called in protected mode.
*/
- set_base(bad_bios_desc, __va((unsigned long)0x40 << 4));
- _set_limit((char *)&bad_bios_desc, 4095 - (0x40 << 4));
+ set_base(&bad_bios_desc, __va((unsigned long)0x40 << 4));
+ _set_limit(&bad_bios_desc, 4095 - (0x40 << 4));

apm_bios_entry.offset = apm_info.bios.offset;
apm_bios_entry.segment = APM_CS;

for (i = 0; i < NR_CPUS; i++) {
struct desc_struct *gdt = get_cpu_gdt_table(i);
- set_base(gdt[segment_index(APM_CS)],
+ set_base(&gdt[segment_index(APM_CS)],
__va((unsigned long)apm_info.bios.cseg << 4));
- set_base(gdt[segment_index(APM_CS_16)],
+ set_base(&gdt[segment_index(APM_CS_16)],
__va((unsigned long)apm_info.bios.cseg_16 << 4));
- set_base(gdt[segment_index(APM_DS)],
+ set_base(&gdt[segment_index(APM_DS)],
__va((unsigned long)apm_info.bios.dseg << 4));
#ifndef APM_RELAX_SEGMENTS
if (apm_info.bios.version == 0x100) {
#endif
/* For ASUS motherboard, Award BIOS rev 110 (and others?) */
- _set_limit((char *)&gdt[segment_index(APM_CS)], 64 * 1024 - 1);
+ _set_limit(&gdt[segment_index(APM_CS)], 64 * 1024 - 1);
/* For some unknown machine. */
- _set_limit((char *)&gdt[segment_index(APM_CS_16)], 64 * 1024 - 1);
+ _set_limit(&gdt[segment_index(APM_CS_16)], 64 * 1024 - 1);
/* For the DEC Hinote Ultra CT475 (and others?) */
- _set_limit((char *)&gdt[segment_index(APM_DS)], 64 * 1024 - 1);
+ _set_limit(&gdt[segment_index(APM_DS)], 64 * 1024 - 1);
#ifndef APM_RELAX_SEGMENTS
} else {
- _set_limit((char *)&gdt[segment_index(APM_CS)],
+ _set_limit(&gdt[segment_index(APM_CS)],
(apm_info.bios.cseg_len - 1) & 0xffff);
- _set_limit((char *)&gdt[segment_index(APM_CS_16)],
+ _set_limit(&gdt[segment_index(APM_CS_16)],
(apm_info.bios.cseg_16_len - 1) & 0xffff);
- _set_limit((char *)&gdt[segment_index(APM_DS)],
+ _set_limit(&gdt[segment_index(APM_DS)],
(apm_info.bios.dseg_len - 1) & 0xffff);
/* workaround for broken BIOSes */
if (apm_info.bios.cseg_len <= apm_info.bios.offset)
- _set_limit((char *)&gdt[segment_index(APM_CS)], 64 * 1024 -1);
+ _set_limit(&gdt[segment_index(APM_CS)], 64 * 1024 -1);
if (apm_info.bios.dseg_len <= 0x40) { /* 0x40 * 4kB == 64kB */
/* for the BIOS that assumes granularity = 1 */
gdt[segment_index(APM_DS)].b |= 0x800000;
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/