diff options
Diffstat (limited to 'include/exec/cpu-defs.h')
| -rw-r--r-- | include/exec/cpu-defs.h | 35 |
1 files changed, 33 insertions, 2 deletions
diff --git a/include/exec/cpu-defs.h b/include/exec/cpu-defs.h index 3f56546066..d5aecaf49e 100644 --- a/include/exec/cpu-defs.h +++ b/include/exec/cpu-defs.h @@ -27,6 +27,7 @@ #include <inttypes.h> #include "qemu/osdep.h" #include "qemu/queue.h" +#include "tcg-target.h" #ifndef CONFIG_USER_ONLY #include "exec/hwaddr.h" #endif @@ -70,8 +71,6 @@ typedef uint64_t target_ulong; #define TB_JMP_PAGE_MASK (TB_JMP_CACHE_SIZE - TB_JMP_PAGE_SIZE) #if !defined(CONFIG_USER_ONLY) -#define CPU_TLB_BITS 8 -#define CPU_TLB_SIZE (1 << CPU_TLB_BITS) /* use a fully associative victim tlb of 8 entries */ #define CPU_VTLB_SIZE 8 @@ -81,6 +80,38 @@ typedef uint64_t target_ulong; #define CPU_TLB_ENTRY_BITS 5 #endif +/* TCG_TARGET_TLB_DISPLACEMENT_BITS is used in CPU_TLB_BITS to ensure that + * the TLB is not unnecessarily small, but still small enough for the + * TLB lookup instruction sequence used by the TCG target. + * + * TCG will have to generate an operand as large as the distance between + * env and the tlb_table[NB_MMU_MODES - 1][0].addend. For simplicity, + * the TCG targets just round everything up to the next power of two, and + * count bits. This works because: 1) the size of each TLB is a largish + * power of two, 2) and because the limit of the displacement is really close + * to a power of two, 3) the offset of tlb_table[0][0] inside env is smaller + * than the size of a TLB. + * + * For example, the maximum displacement 0xFFF0 on PPC and MIPS, but TCG + * just says "the displacement is 16 bits". TCG_TARGET_TLB_DISPLACEMENT_BITS + * then ensures that tlb_table at least 0x8000 bytes large ("not unnecessarily + * small": 2^15). The operand then will come up smaller than 0xFFF0 without + * any particular care, because the TLB for a single MMU mode is larger than + * 0x10000-0xFFF0=16 bytes. In the end, the maximum value of the operand + * could be something like 0xC000 (the offset of the last TLB table) plus + * 0x18 (the offset of the addend field in each TLB entry) plus the offset + * of tlb_table inside env (which is non-trivial but not huge). + */ +#define CPU_TLB_BITS \ + MIN(8, \ + TCG_TARGET_TLB_DISPLACEMENT_BITS - CPU_TLB_ENTRY_BITS - \ + (NB_MMU_MODES <= 1 ? 0 : \ + NB_MMU_MODES <= 2 ? 1 : \ + NB_MMU_MODES <= 4 ? 2 : \ + NB_MMU_MODES <= 8 ? 3 : 4)) + +#define CPU_TLB_SIZE (1 << CPU_TLB_BITS) + typedef struct CPUTLBEntry { /* bit TARGET_LONG_BITS to TARGET_PAGE_BITS : virtual address bit TARGET_PAGE_BITS-1..4 : Nonzero for accesses that should not |