i386 boot: replace boot_ioremap with enhanced bt_ioremap - enhance bt_ioremap

This patch makes it possible for bt_ioremap() to be used before
paging_init(), via providing an early implementation of set_fixmap()
that can be used before paging_init().

This way boot_ioremap() can be replaced by bt_ioremap().

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

3 files changed, 88 insertions, 2 deletions

diff --git a/arch/x86/kernel/setup_32.c b/arch/x86/kernel/setup_32.c
index 83ba3ca5f431..35db426de300 100644
--- a/arch/x86/kernel/setup_32.c
+++ b/arch/x86/kernel/setup_32.c
@@ -697,6 +697,7 @@ void __init setup_arch(char **cmdline_p)
         memcpy(&boot_cpu_data, &new_cpu_data, sizeof(new_cpu_data));
         pre_setup_arch_hook();
         early_cpu_init();
+        bt_ioremap_init();
 
 #ifdef CONFIG_EFI
         if (!strncmp((char *)&boot_params.efi_info.efi_loader_signature,
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 206e3f6800b9..f4e1894367a6 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -429,9 +429,11 @@ static void __init pagetable_init (void)
          * Fixed mappings, only the page table structure has to be
          * created - mappings will be set by set_fixmap():
          */
+        bt_ioremap_clear();
         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
         end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
         page_table_range_init(vaddr, end, pgd_base);
+        bt_ioremap_reset();
 
         permanent_kmaps_init(pgd_base);
 
diff --git a/arch/x86/mm/ioremap_32.c b/arch/x86/mm/ioremap_32.c
index ef0f6a452ee1..fd1f5b6cfa20 100644
--- a/arch/x86/mm/ioremap_32.c
+++ b/arch/x86/mm/ioremap_32.c
@@ -208,6 +208,89 @@ void iounmap(volatile void __iomem *addr)
 }
 EXPORT_SYMBOL(iounmap);
 
+static __initdata int after_paging_init;
+static __initdata unsigned long bm_pte[1024]
+                                __attribute__((aligned(PAGE_SIZE)));
+
+static inline unsigned long * __init bt_ioremap_pgd(unsigned long addr)
+{
+        return (unsigned long *)swapper_pg_dir + ((addr >> 22) & 1023);
+}
+
+static inline unsigned long * __init bt_ioremap_pte(unsigned long addr)
+{
+        return bm_pte + ((addr >> PAGE_SHIFT) & 1023);
+}
+
+void __init bt_ioremap_init(void)
+{
+        unsigned long *pgd;
+
+        pgd = bt_ioremap_pgd(fix_to_virt(FIX_BTMAP_BEGIN));
+        *pgd = __pa(bm_pte) | _PAGE_TABLE;
+        memset(bm_pte, 0, sizeof(bm_pte));
+        BUG_ON(pgd != bt_ioremap_pgd(fix_to_virt(FIX_BTMAP_END)));
+}
+
+void __init bt_ioremap_clear(void)
+{
+        unsigned long *pgd;
+
+        pgd = bt_ioremap_pgd(fix_to_virt(FIX_BTMAP_BEGIN));
+        *pgd = 0;
+        __flush_tlb_all();
+}
+
+void __init bt_ioremap_reset(void)
+{
+        enum fixed_addresses idx;
+        unsigned long *pte, phys, addr;
+
+        after_paging_init = 1;
+        for (idx = FIX_BTMAP_BEGIN; idx <= FIX_BTMAP_END; idx--) {
+                addr = fix_to_virt(idx);
+                pte = bt_ioremap_pte(addr);
+                if (!*pte & _PAGE_PRESENT) {
+                        phys = *pte & PAGE_MASK;
+                        set_fixmap(idx, phys);
+                }
+        }
+}
+
+static void __init __bt_set_fixmap(enum fixed_addresses idx,
+                                   unsigned long phys, pgprot_t flags)
+{
+        unsigned long *pte, addr = __fix_to_virt(idx);
+
+        if (idx >= __end_of_fixed_addresses) {
+                BUG();
+                return;
+        }
+        pte = bt_ioremap_pte(addr);
+        if (pgprot_val(flags))
+                *pte = (phys & PAGE_MASK) | pgprot_val(flags);
+        else
+                *pte = 0;
+        __flush_tlb_one(addr);
+}
+
+static inline void __init bt_set_fixmap(enum fixed_addresses idx,
+                                        unsigned long phys)
+{
+        if (after_paging_init)
+                set_fixmap(idx, phys);
+        else
+                __bt_set_fixmap(idx, phys, PAGE_KERNEL);
+}
+
+static inline void __init bt_clear_fixmap(enum fixed_addresses idx)
+{
+        if (after_paging_init)
+                clear_fixmap(idx);
+        else
+                __bt_set_fixmap(idx, 0, __pgprot(0));
+}
+
 void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)
 {
         unsigned long offset, last_addr;
@@ -244,7 +327,7 @@ void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)
          */
         idx = FIX_BTMAP_BEGIN;
         while (nrpages > 0) {
-                set_fixmap(idx, phys_addr);
+                bt_set_fixmap(idx, phys_addr);
                 phys_addr += PAGE_SIZE;
                 --idx;
                 --nrpages;
@@ -267,7 +350,7 @@ void __init bt_iounmap(void *addr, unsigned long size)
 
         idx = FIX_BTMAP_BEGIN;
         while (nrpages > 0) {
-                clear_fixmap(idx);
+                bt_clear_fixmap(idx);
                 --idx;
                 --nrpages;
         }