[MIPS] Load modules to CKSEG0 if CONFIG_BUILD_ELF64=n

This is a patch to load 64-bit modules to CKSEG0 so that can be
compiled with -msym32 option.  This makes each module ~10% smaller.

* introduce MODULE_START and MODULE_END
* custom module_alloc()
* PGD for modules
* change XTLB refill handler synthesizer
* enable -msym32 for modules again
  (revert ca78b1a5c6a6e70e052d3ea253828e49b5d07c8a)

New XTLB refill handler looks like this:

80000080 dmfc0   k0,C0_BADVADDR
80000084 bltz    k0,800000e4			# goto l_module_alloc
80000088 lui     k1,0x8046			# %high(pgd_current)
8000008c ld      k1,24600(k1)			# %low(pgd_current)
80000090 dsrl    k0,k0,0x1b			# l_vmalloc_done:
80000094 andi    k0,k0,0x1ff8
80000098 daddu   k1,k1,k0
8000009c dmfc0   k0,C0_BADVADDR
800000a0 ld      k1,0(k1)
800000a4 dsrl    k0,k0,0x12
800000a8 andi    k0,k0,0xff8
800000ac daddu   k1,k1,k0
800000b0 dmfc0   k0,C0_XCONTEXT
800000b4 ld      k1,0(k1)
800000b8 andi    k0,k0,0xff0
800000bc daddu   k1,k1,k0
800000c0 ld      k0,0(k1)
800000c4 ld      k1,8(k1)
800000c8 dsrl    k0,k0,0x6
800000cc mtc0    k0,C0_ENTRYLO0
800000d0 dsrl    k1,k1,0x6
800000d4 mtc0    k1,C0_ENTRYL01
800000d8 nop
800000dc tlbwr
800000e0 eret
800000e4 dsll    k1,k0,0x2			# l_module_alloc:
800000e8 bgez    k1,80000008			# goto l_vmalloc
800000ec lui     k1,0xc000
800000f0 dsubu   k0,k0,k1
800000f4 lui     k1,0x8046			# %high(module_pg_dir)
800000f8 beq     zero,zero,80000000
800000fc nop
80000000 beq     zero,zero,80000090		# goto l_vmalloc_done
80000004 daddiu  k1,k1,0x4000
80000008 dsll32  k1,k1,0x0			# l_vmalloc:
8000000c dsubu   k0,k0,k1
80000010 beq     zero,zero,80000090		# goto l_vmalloc_done
80000014 lui     k1,0x8046			# %high(swapper_pg_dir)

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/asm-mips/pgtable-64.h b/include/asm-mips/pgtable-64.h
index 7e7320300aa3..b9b1e86493ee 100644
--- a/include/asm-mips/pgtable-64.h
+++ b/include/asm-mips/pgtable-64.h
@@ -14,6 +14,7 @@
 #include <asm/addrspace.h>
 #include <asm/page.h>
 #include <asm/cachectl.h>
+#include <asm/fixmap.h>
 
 #include <asm-generic/pgtable-nopud.h>
 
@@ -103,6 +104,13 @@
 #define VMALLOC_START           MAP_BASE
 #define VMALLOC_END     \
         (VMALLOC_START + PTRS_PER_PGD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE)
+#if defined(CONFIG_MODULES) && !defined(CONFIG_BUILD_ELF64) && \
+        VMALLOC_START != CKSSEG
+/* Load modules into 32bit-compatible segment. */
+#define MODULE_START    CKSSEG
+#define MODULE_END      (FIXADDR_START-2*PAGE_SIZE)
+extern pgd_t module_pg_dir[PTRS_PER_PGD];
+#endif
 
 #define pte_ERROR(e) \
         printk("%s:%d: bad pte %016lx.\n", __FILE__, __LINE__, pte_val(e))
@@ -174,7 +182,12 @@ static inline void pud_clear(pud_t *pudp)
 #define __pmd_offset(address)   pmd_index(address)
 
 /* to find an entry in a kernel page-table-directory */
+#ifdef MODULE_START
+#define pgd_offset_k(address) \
+        ((address) >= MODULE_START ? module_pg_dir : pgd_offset(&init_mm, 0UL))
+#else
 #define pgd_offset_k(address) pgd_offset(&init_mm, 0UL)
+#endif
 
 #define pgd_index(address)      (((address) >> PGDIR_SHIFT) & (PTRS_PER_PGD-1))
 #define pmd_index(address)      (((address) >> PMD_SHIFT) & (PTRS_PER_PMD-1))