Commit 222f23f5 authored by Dr. David Alan Gilbert's avatar Dr. David Alan Gilbert Committed by Andrzej Zaborowski
Browse files

tcg/arm: remove fixed map code buffer restriction 



On ARM, don't map the code buffer at a fixed location, and fix up the
call/goto tcg routines to let it do long jumps.

Mapping the code buffer at a fixed address could sometimes result in it being
mapped over the top of the heap with pretty random results.

Signed-off-by: default avatarDr. David Alan Gilbert <david.gilbert@linaro.org>
Signed-off-by: default avatarAndrzej Zaborowski <andrew.zaborowski@intel.com>
parent 23ce84b1

exec.c

+1 −3
Original line number Diff line number Diff line
@@ -497,9 +497,7 @@ static void code_gen_alloc(unsigned long tb_size) 
        if (code_gen_buffer_size > (512 * 1024 * 1024))

            code_gen_buffer_size = (512 * 1024 * 1024);

#elif defined(__arm__)

        /* Map the buffer below 32M, so we can use direct calls and branches */

        flags |= MAP_FIXED;

        start = (void *) 0x01000000UL;

        /* Keep the buffer no bigger than 16GB to branch between blocks */

        if (code_gen_buffer_size > 16 * 1024 * 1024)

            code_gen_buffer_size = 16 * 1024 * 1024;

#elif defined(__s390x__)

tcg/arm/tcg-target.c

+12 −19
Original line number Diff line number Diff line
@@ -842,6 +842,12 @@ static inline void tcg_out_st8(TCGContext *s, int cond, 
        tcg_out_st8_12(s, cond, rd, rn, offset);

}



/* The _goto case is normally between TBs within the same code buffer,

 * and with the code buffer limited to 16GB we shouldn't need the long

 * case.

 *

 * .... except to the prologue that is in its own buffer.

 */

static inline void tcg_out_goto(TCGContext *s, int cond, uint32_t addr)

{

    int32_t val;
@@ -855,22 +861,20 @@ static inline void tcg_out_goto(TCGContext *s, int cond, uint32_t addr) 
    if (val - 8 < 0x01fffffd && val - 8 > -0x01fffffd)

        tcg_out_b(s, cond, val);

    else {

#if 1

        tcg_abort();

#else

        if (cond == COND_AL) {

            tcg_out_ld32_12(s, COND_AL, TCG_REG_PC, TCG_REG_PC, -4);

            tcg_out32(s, addr); /* XXX: This is l->u.value, can we use it? */

            tcg_out32(s, addr);

        } else {

            tcg_out_movi32(s, cond, TCG_REG_R8, val - 8);

            tcg_out_dat_reg(s, cond, ARITH_ADD,

                            TCG_REG_PC, TCG_REG_PC,

                            TCG_REG_R8, SHIFT_IMM_LSL(0));

        }

#endif

    }

}



/* The call case is mostly used for helpers - so it's not unreasonable

 * for them to be beyond branch range */

static inline void tcg_out_call(TCGContext *s, uint32_t addr)

{

    int32_t val;
@@ -887,20 +891,9 @@ static inline void tcg_out_call(TCGContext *s, uint32_t addr) 
            tcg_out_bl(s, COND_AL, val);

        }

    } else {

#if 1

        tcg_abort();

#else

        if (cond == COND_AL) {

            tcg_out_dat_imm(s, cond, ARITH_ADD, TCG_REG_R14, TCG_REG_PC, 4);

        tcg_out_dat_imm(s, COND_AL, ARITH_ADD, TCG_REG_R14, TCG_REG_PC, 4);

        tcg_out_ld32_12(s, COND_AL, TCG_REG_PC, TCG_REG_PC, -4);

            tcg_out32(s, addr); /* XXX: This is l->u.value, can we use it? */

        } else {

            tcg_out_movi32(s, cond, TCG_REG_R9, addr);

            tcg_out_dat_reg(s, cond, ARITH_MOV, TCG_REG_R14, 0,

                            TCG_REG_PC, SHIFT_IMM_LSL(0));

            tcg_out_bx(s, cond, TCG_REG_R9);

        }

#endif

        tcg_out32(s, addr);

    }

}