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Subject[PATCH 3/4] Prep for paravirt: desc.h clearer parameter names, some code motion
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Jeremy Fitzhardinge's patch to clarify arg names in asm/desc.h

"a" and "b" are better named "low" and "high"; Rusty mixed them up
once with amusing results. Also change __u32 to u32 while there (this
must be kernel-only code, given the DECLARE_PER_CPU in the file
above).

Also moves set_ldt up higher in header, in preparation for paravirt.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

===================================================================
--- a/include/asm-i386/desc.h
+++ b/include/asm-i386/desc.h
@@ -32,19 +32,19 @@ extern struct desc_struct idt_table[];
extern struct desc_struct idt_table[];
extern void set_intr_gate(unsigned int irq, void * addr);

-static inline void pack_descriptor(__u32 *a, __u32 *b,
+static inline void pack_descriptor(u32 *low, u32 *high,
unsigned long base, unsigned long limit, unsigned char type, unsigned char flags)
{
- *a = ((base & 0xffff) << 16) | (limit & 0xffff);
- *b = (base & 0xff000000) | ((base & 0xff0000) >> 16) |
+ *low = ((base & 0xffff) << 16) | (limit & 0xffff);
+ *high = (base & 0xff000000) | ((base & 0xff0000) >> 16) |
(limit & 0x000f0000) | ((type & 0xff) << 8) | ((flags & 0xf) << 20);
}

-static inline void pack_gate(__u32 *a, __u32 *b,
+static inline void pack_gate(u32 *low, u32 *high,
unsigned long base, unsigned short seg, unsigned char type, unsigned char flags)
{
- *a = (seg << 16) | (base & 0xffff);
- *b = (base & 0xffff0000) | ((type & 0xff) << 8) | (flags & 0xff);
+ *low = (seg << 16) | (base & 0xffff);
+ *high = (base & 0xffff0000) | ((type & 0xff) << 8) | (flags & 0xff);
}

#define DESCTYPE_LDT 0x82 /* present, system, DPL-0, LDT */
@@ -78,47 +78,47 @@ static inline void load_TLS(struct threa
#undef C
}

-static inline void write_dt_entry(void *dt, int entry, __u32 entry_a, __u32 entry_b)
-{
- __u32 *lp = (__u32 *)((char *)dt + entry*8);
- *lp = entry_a;
- *(lp+1) = entry_b;
-}
-
-#define write_ldt_entry(dt, entry, a, b) write_dt_entry(dt, entry, a, b)
-#define write_gdt_entry(dt, entry, a, b) write_dt_entry(dt, entry, a, b)
-#define write_idt_entry(dt, entry, a, b) write_dt_entry(dt, entry, a, b)
-
-static inline void _set_gate(int gate, unsigned int type, void *addr, unsigned short seg)
-{
- __u32 a, b;
- pack_gate(&a, &b, (unsigned long)addr, seg, type, 0);
- write_idt_entry(idt_table, gate, a, b);
-}
-
-static inline void __set_tss_desc(unsigned int cpu, unsigned int entry, const void *addr)
-{
- __u32 a, b;
- pack_descriptor(&a, &b, (unsigned long)addr,
- offsetof(struct tss_struct, __cacheline_filler) - 1,
- DESCTYPE_TSS, 0);
- write_gdt_entry(get_cpu_gdt_table(cpu), entry, a, b);
-}
-
static inline void set_ldt(void *addr, unsigned int entries)
{
if (likely(entries == 0))
__asm__ __volatile__("lldt %w0"::"q" (0));
else {
unsigned cpu = smp_processor_id();
- __u32 a, b;
-
- pack_descriptor(&a, &b, (unsigned long)addr,
+ u32 low, high;
+
+ pack_descriptor(&low, &high, (unsigned long)addr,
entries * sizeof(struct desc_struct) - 1,
DESCTYPE_LDT, 0);
- write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_LDT, a, b);
+ write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_LDT, low, high);
__asm__ __volatile__("lldt %w0"::"q" (GDT_ENTRY_LDT*8));
}
+}
+
+#define write_ldt_entry(dt, entry, low, high) write_dt_entry(dt,entry,low,high)
+#define write_gdt_entry(dt, entry, low, high) write_dt_entry(dt,entry,low,high)
+#define write_idt_entry(dt, entry, low, high) write_dt_entry(dt,entry,low,high)
+
+static inline void write_dt_entry(void *dt, int entry, u32 entry_low, u32 entry_high)
+{
+ u32 *lp = (u32 *)((char *)dt + entry*8);
+ lp[0] = entry_low;
+ lp[1] = entry_high;
+}
+
+static inline void _set_gate(int gate, unsigned int type, void *addr, unsigned short seg)
+{
+ u32 low, high;
+ pack_gate(&low, &high, (unsigned long)addr, seg, type, 0);
+ write_idt_entry(idt_table, gate, low, high);
+}
+
+static inline void __set_tss_desc(unsigned int cpu, unsigned int entry, const void *addr)
+{
+ u32 low, high;
+ pack_descriptor(&low, &high, (unsigned long)addr,
+ offsetof(struct tss_struct, __cacheline_filler) - 1,
+ DESCTYPE_TSS, 0);
+ write_gdt_entry(get_cpu_gdt_table(cpu), entry, low, high);
}

#define set_tss_desc(cpu,addr) __set_tss_desc(cpu, GDT_ENTRY_TSS, addr)

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