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#include "arm/assemble.h"
static NOINLINE UNUSED void transform_dis_data(struct transform_dis_ctx *ctx,
unsigned o0, unsigned o1, unsigned o2, unsigned o3, unsigned out_mask) {
#ifdef TRANSFORM_DIS_VERBOSE
printf("transform_dis_data: (%p) %x %x %x %x out_mask=%x\n", (void *) ctx->pc,
o0, o1, o2, o3, out_mask);
#endif
/* We only care if at least one op is PC, so quickly test that. */
if (((o0 | o1 | o2 | o3) & 15) != 15)
return;
unsigned *newval = ctx->newval;
newval[0] = o0;
newval[1] = o1;
newval[2] = o2;
newval[3] = o3;
void **codep = ctx->rewritten_ptr_ptr;
struct assemble_ctx actx = {ctx->rewritten_ptr_ptr, ctx->arch.pc_low_bit};
/* A few cases:
* 1. Move to PC that does not read PC. Probably fine.
* 2. Move to PC that does read PC, e.g. 'ldrls pc, [pc, r0, lsl #2]'.
* This is different from #4 mainly in that we can't need to do
* something like pop {temp, pc}. Not terribly plausible (only likely
* in non-position-independent code in ARM mode, and I can't get it to
* happen in the first 8 bytes then), but we may as well handle it.
* 3. Read of PC that does not read the register(s) it writes, e.g. adr r3,
* X. In this case we can use that register as a temporary.
* 4. Read of PC that does, or doesn't have any output register, e.g. add
* r3, pc. In this case we use the stack because reliably finding a
* free register would be work, and might not even be possible (thumb
* mov r9, r0; mov r12, r1; <some PC using insn(s)>)
* the out register is always first.
*/
uint16_t in_regs = 0;
int out_reg = -1;
for (int i = 0; i < 4; i++) {
if (out_mask & 1 << i)
out_reg = newval[i];
else if (newval[i] != null_op)
in_regs |= 1 << newval[i];
}
if (out_mask & IS_LDRD_STRD)
in_regs |= 1 << (newval[0] + 1);
uint32_t pc = ctx->pc + (ctx->arch.pc_low_bit ? 4 : 8);
int scratch = __builtin_ctz(~(in_regs | (1 << out_reg)));
#ifdef TRANSFORM_DIS_VERBOSE
printf("transform_dis_data: in_regs=%x out_reg=%d pc=%x scratch=%d\n",
in_regs, out_reg, pc, scratch);
#endif
if (out_reg == 15) {
if (in_regs & 1 << 15)
return; /* case 1 */
/* case 2 */
PUSHone(actx, scratch);
PUSHone(actx, scratch);
MOVW_MOVT(actx, scratch, pc);
for (int i = 0; i < 4; i++)
if (newval[i] == 15)
newval[i] = scratch;
ctx->write_newop_here = *codep; *codep += ctx->op_size;
STRri(actx, scratch, 13, 4);
POPmulti(actx, 1 << scratch | 1 << 15);
transform_dis_ret(ctx);
} else {
if (out_reg != -1 && !(in_regs & 1 << out_reg)) {
/* case 3 - ignore scratch */
MOVW_MOVT(actx, out_reg, pc);
for (int i = 0; i < 4; i++)
if (newval[i] == 15)
newval[i] = out_reg;
ctx->write_newop_here = *codep; *codep += ctx->op_size;
} else {
/* case 4 */
PUSHone(actx, scratch);
MOVW_MOVT(actx, scratch, pc);
for (int i = 0; i < 4; i++)
if (newval[i] == 15)
newval[i] = scratch;
ctx->write_newop_here = *codep; *codep += ctx->op_size;
POPone(actx, scratch);
}
}
ctx->modify = true;
#ifdef TRANSFORM_DIS_VERBOSE
printf("transform_dis_data: => %x %x %x %x\n",
newval[0], newval[1], newval[2], newval[3]);
#endif
}
static NOINLINE UNUSED void transform_dis_pcrel(struct transform_dis_ctx *ctx,
uintptr_t dpc, unsigned reg, enum pcrel_load_mode load_mode) {
#ifdef TRANSFORM_DIS_VERBOSE
printf("transform_dis_pcrel: (%p) dpc=%p reg=%x mode=%d\n", (void *) ctx->pc,
(void *) dpc, reg, load_mode);
#endif
ctx->write_newop_here = NULL;
struct assemble_ctx actx = {ctx->rewritten_ptr_ptr, ctx->arch.pc_low_bit};
if (reg == 15) {
int scratch = 0;
PUSHone(actx, scratch);
PUSHone(actx, scratch);
MOVW_MOVT(actx, scratch, dpc);
if (load_mode != PLM_ADR)
LDRxi(actx, scratch, scratch, 0, load_mode);
STRri(actx, scratch, 13, 4);
POPmulti(actx, 1 << scratch | 1 << 15);
transform_dis_ret(ctx);
} else {
MOVW_MOVT(actx, reg, dpc);
if (load_mode != PLM_ADR)
LDRxi(actx, reg, reg, 0, load_mode);
}
}
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