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tcg/arm: fix TLB access in qemu-ld/st ops 

The TCG arm backend considers likely that the offset to the TLB
entries does not exceed 12 bits for mem_index = 0. In practice this is
not true for at least the MIPS target.

The current patch fixes that by loading the bits 23-12 with a separate
instruction, and using loads with address writeback, independently of
the value of mem_idx. In total this allow a 24-bit offset, which is a
lot more than needed.

Cc: Andrzej Zaborowski <balrogg@gmail.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-stable@nongnu.org
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Aurelien Jarno 2012-10-09 21:53:11 +02:00
parent 1ccbc28512
commit d17bd1d8cc
1 changed files with 42 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

78
tcg/arm/tcg-target.c
View File

@ -639,6 +639,22 @@ static inline void tcg_out_ld32_12(TCGContext *s, int cond,
(rn << 16) | (rd << 12) | ((-im) & 0xfff));
}
/* Offset pre-increment with base writeback. */
static inline void tcg_out_ld32_12wb(TCGContext *s, int cond,
int rd, int rn, tcg_target_long im)
{
/* ldr with writeback and both register equals is UNPREDICTABLE */
assert(rd != rn);
if (im >= 0) {
tcg_out32(s, (cond << 28) | 0x05b00000 |
(rn << 16) | (rd << 12) | (im & 0xfff));
} else {
tcg_out32(s, (cond << 28) | 0x05300000 |
(rn << 16) | (rd << 12) | ((-im) & 0xfff));
}
}
static inline void tcg_out_st32_12(TCGContext *s, int cond,
int rd, int rn, tcg_target_long im)
{
@ -1071,7 +1087,7 @@ static inline void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, int opc)
{
int addr_reg, data_reg, data_reg2, bswap;
#ifdef CONFIG_SOFTMMU
int mem_index, s_bits;
int mem_index, s_bits, tlb_offset;
TCGReg argreg;
# if TARGET_LONG_BITS == 64
int addr_reg2;
@ -1111,19 +1127,15 @@ static inline void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, int opc)
TCG_REG_R0, TCG_REG_R8, CPU_TLB_SIZE - 1);
tcg_out_dat_reg(s, COND_AL, ARITH_ADD, TCG_REG_R0, TCG_AREG0,
TCG_REG_R0, SHIFT_IMM_LSL(CPU_TLB_ENTRY_BITS));
/* In the
* ldr r1 [r0, #(offsetof(CPUArchState, tlb_table[mem_index][0].addr_read))]
* below, the offset is likely to exceed 12 bits if mem_index != 0 and
* not exceed otherwise, so use an
* add r0, r0, #(mem_index * sizeof *CPUArchState.tlb_table)
* before.
*/
if (mem_index)
/* We assume that the offset is contained within 20 bits. */
tlb_offset = offsetof(CPUArchState, tlb_table[mem_index][0].addr_read);
assert(tlb_offset & ~0xfffff == 0);
if (tlb_offset > 0xfff) {
tcg_out_dat_imm(s, COND_AL, ARITH_ADD, TCG_REG_R0, TCG_REG_R0,
(mem_index << (TLB_SHIFT & 1)) |
((16 - (TLB_SHIFT >> 1)) << 8));
tcg_out_ld32_12(s, COND_AL, TCG_REG_R1, TCG_REG_R0,
offsetof(CPUArchState, tlb_table[0][0].addr_read));
0xa00 | (tlb_offset >> 12));
tlb_offset &= 0xfff;
}
tcg_out_ld32_12wb(s, COND_AL, TCG_REG_R1, TCG_REG_R0, tlb_offset);
tcg_out_dat_reg(s, COND_AL, ARITH_CMP, 0, TCG_REG_R1,
TCG_REG_R8, SHIFT_IMM_LSL(TARGET_PAGE_BITS));
/* Check alignment. */
@ -1131,15 +1143,14 @@ static inline void tcg_out_qemu_ld(TCGContext *s, const TCGArg *args, int opc)
tcg_out_dat_imm(s, COND_EQ, ARITH_TST,
0, addr_reg, (1 << s_bits) - 1);
# if TARGET_LONG_BITS == 64
/* XXX: possibly we could use a block data load or writeback in
* the first access. */
tcg_out_ld32_12(s, COND_EQ, TCG_REG_R1, TCG_REG_R0,
offsetof(CPUArchState, tlb_table[0][0].addr_read) + 4);
/* XXX: possibly we could use a block data load in the first access. */
tcg_out_ld32_12(s, COND_EQ, TCG_REG_R1, TCG_REG_R0, 4);
tcg_out_dat_reg(s, COND_EQ, ARITH_CMP, 0,
TCG_REG_R1, addr_reg2, SHIFT_IMM_LSL(0));
# endif
tcg_out_ld32_12(s, COND_EQ, TCG_REG_R1, TCG_REG_R0,
offsetof(CPUArchState, tlb_table[0][0].addend));
offsetof(CPUTLBEntry, addend)
- offsetof(CPUTLBEntry, addr_read));
switch (opc) {
case 0:
@ -1288,7 +1299,7 @@ static inline void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, int opc)
{
int addr_reg, data_reg, data_reg2, bswap;
#ifdef CONFIG_SOFTMMU
int mem_index, s_bits;
int mem_index, s_bits, tlb_offset;
TCGReg argreg;
# if TARGET_LONG_BITS == 64
int addr_reg2;
@ -1325,19 +1336,15 @@ static inline void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, int opc)
TCG_REG_R0, TCG_REG_R8, CPU_TLB_SIZE - 1);
tcg_out_dat_reg(s, COND_AL, ARITH_ADD, TCG_REG_R0,
TCG_AREG0, TCG_REG_R0, SHIFT_IMM_LSL(CPU_TLB_ENTRY_BITS));
/* In the
* ldr r1 [r0, #(offsetof(CPUArchState, tlb_table[mem_index][0].addr_write))]
* below, the offset is likely to exceed 12 bits if mem_index != 0 and
* not exceed otherwise, so use an
* add r0, r0, #(mem_index * sizeof *CPUArchState.tlb_table)
* before.
*/
if (mem_index)
/* We assume that the offset is contained within 20 bits. */
tlb_offset = offsetof(CPUArchState, tlb_table[mem_index][0].addr_write);
assert(tlb_offset & ~0xfffff == 0);
if (tlb_offset > 0xfff) {
tcg_out_dat_imm(s, COND_AL, ARITH_ADD, TCG_REG_R0, TCG_REG_R0,
(mem_index << (TLB_SHIFT & 1)) |
((16 - (TLB_SHIFT >> 1)) << 8));
tcg_out_ld32_12(s, COND_AL, TCG_REG_R1, TCG_REG_R0,
offsetof(CPUArchState, tlb_table[0][0].addr_write));
0xa00 | (tlb_offset >> 12));
tlb_offset &= 0xfff;
}
tcg_out_ld32_12wb(s, COND_AL, TCG_REG_R1, TCG_REG_R0, tlb_offset);
tcg_out_dat_reg(s, COND_AL, ARITH_CMP, 0, TCG_REG_R1,
TCG_REG_R8, SHIFT_IMM_LSL(TARGET_PAGE_BITS));
/* Check alignment. */
@ -1345,15 +1352,14 @@ static inline void tcg_out_qemu_st(TCGContext *s, const TCGArg *args, int opc)
tcg_out_dat_imm(s, COND_EQ, ARITH_TST,
0, addr_reg, (1 << s_bits) - 1);
# if TARGET_LONG_BITS == 64
/* XXX: possibly we could use a block data load or writeback in
* the first access. */
tcg_out_ld32_12(s, COND_EQ, TCG_REG_R1, TCG_REG_R0,
offsetof(CPUArchState, tlb_table[0][0].addr_write) + 4);
/* XXX: possibly we could use a block data load in the first access. */
tcg_out_ld32_12(s, COND_EQ, TCG_REG_R1, TCG_REG_R0, 4);
tcg_out_dat_reg(s, COND_EQ, ARITH_CMP, 0,
TCG_REG_R1, addr_reg2, SHIFT_IMM_LSL(0));
# endif
tcg_out_ld32_12(s, COND_EQ, TCG_REG_R1, TCG_REG_R0,
offsetof(CPUArchState, tlb_table[0][0].addend));
offsetof(CPUTLBEntry, addend)
- offsetof(CPUTLBEntry, addr_write));
switch (opc) {
case 0: