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Always emit veneers for non-bl jumps to ARM code

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It is unlikely for any ARM code to be close enough to not have needed
a veneer, but it is possible, especially if running in a program with
another JIT library.
This commit is contained in:
Icecream95 2020-04-09 22:10:15 +12:00
parent 52ec8aefa0
commit 11b9d3744e
No known key found for this signature in database
GPG key ID: 339D18472C107D93
3 changed files with 25 additions and 14 deletions
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4
lightening/aarch64.c
View file

@ -90,9 +90,9 @@ DEFINE_ENCODER(size, 2, 22, unsigned, uint32_t)
{ \
return read_signed_bitfield(*loc, kind##_width, kind##_shift); \
} \
static int offset_in_##name##_range(ptrdiff_t diff) maybe_unused; \
static int offset_in_##name##_range(ptrdiff_t diff, int flags) maybe_unused; \
static int \
offset_in_##name##_range(ptrdiff_t diff) \
offset_in_##name##_range(ptrdiff_t diff, int flags) \
{ \
return in_signed_range(diff, kind##_width); \
} \

26
lightening/arm-cpu.c
View file

@ -186,6 +186,8 @@
#define _NOREG (jit_gpr_regno(_PC))
#define JIT_RELOC_B JIT_RELOC_FLAG_0
static void
emit_wide_thumb(jit_state_t *_jit, uint32_t inst)
{
@ -265,9 +267,12 @@ write_wide_thumb(uint32_t *loc, uint32_t v)
}
static int
offset_in_jmp_range(int32_t offset)
offset_in_jmp_range(int32_t offset, int flags)
{
return -0x1000000 <= offset && offset <= 0xffffff;
if (!(offset & 1) && flags | JIT_RELOC_B)
return 0;
else
return -0x1000000 <= offset && offset <= 0xffffff;
}
static int32_t
@ -295,7 +300,7 @@ static const uint32_t thumb_jump_mask = 0xf800d000;
static uint32_t
encode_thumb_jump(int32_t v)
{
ASSERT(offset_in_jmp_range(v));
ASSERT(offset_in_jmp_range(v, 0));
v >>= 1;
uint32_t s = !!(v & 0x800000);
uint32_t i1 = !!(v & 0x400000);
@ -339,8 +344,10 @@ emit_thumb_jump(jit_state_t *_jit, uint32_t inst)
while (1) {
uint8_t *pc_base = _jit->pc.uc + 4;
int32_t off = (uint8_t*)jit_address(_jit) - pc_base;
jit_reloc_t ret =
jit_reloc (_jit, JIT_RELOC_JMP_WITH_VENEER, 0, _jit->pc.uc, pc_base, 0);
enum jit_reloc_kind kind = JIT_RELOC_JMP_WITH_VENEER;
if (inst == THUMB2_B)
kind |= JIT_RELOC_B;
jit_reloc_t ret = jit_reloc (_jit, kind, 0, _jit->pc.uc, pc_base, 0);
uint8_t thumb_jump_width = 24;
if (add_pending_literal(_jit, ret, thumb_jump_width - 1)) {
emit_wide_thumb(_jit, patch_thumb_jump(inst, off));
@ -350,9 +357,12 @@ emit_thumb_jump(jit_state_t *_jit, uint32_t inst)
}
static int
offset_in_jcc_range(int32_t v)
offset_in_jcc_range(int32_t v, int flags)
{
return -0x100000 <= v && v <= 0xfffff;
if (!(v & 1))
return 0;
else
return -0x100000 <= v && v <= 0xfffff;
}
static int32_t
@ -378,7 +388,7 @@ static const uint32_t thumb_cc_jump_mask = 0xfbc0d000;
static uint32_t
encode_thumb_cc_jump(int32_t v)
{
ASSERT(offset_in_jcc_range(v));
ASSERT(offset_in_jcc_range(v, 0));
v >>= 1;
uint32_t s = !!(v & 0x80000);
uint32_t j2 = !!(v & 0x40000);

9
lightening/lightening.c
View file

@ -105,11 +105,11 @@ enum guard_pool { GUARD_NEEDED, NO_GUARD_NEEDED };
static void emit_literal_pool(jit_state_t *_jit, enum guard_pool guard);
static int32_t read_jmp_offset(uint32_t *loc);
static int offset_in_jmp_range(ptrdiff_t offset);
static int offset_in_jmp_range(ptrdiff_t offset, int flags);
static void patch_jmp_offset(uint32_t *loc, ptrdiff_t offset);
static void patch_veneer_jmp_offset(uint32_t *loc, ptrdiff_t offset);
static int32_t read_jcc_offset(uint32_t *loc);
static int offset_in_jcc_range(ptrdiff_t offset);
static int offset_in_jcc_range(ptrdiff_t offset, int flags);
static void patch_jcc_offset(uint32_t *loc, ptrdiff_t offset);
static void patch_veneer_jcc_offset(uint32_t *loc, ptrdiff_t offset);
static void patch_veneer(uint32_t *loc, jit_pointer_t addr);
@ -380,6 +380,7 @@ jit_patch_there(jit_state_t* _jit, jit_reloc_t reloc, jit_pointer_t addr)
ptrdiff_t diff = (uint8_t*)addr - pc_base;
ASSERT((diff & ((1 << reloc.rsh) - 1)) == 0);
diff >>= reloc.rsh;
int flags = reloc.kind & ~JIT_RELOC_MASK;
switch (reloc.kind & JIT_RELOC_MASK)
{
@ -406,7 +407,7 @@ jit_patch_there(jit_state_t* _jit, jit_reloc_t reloc, jit_pointer_t addr)
uint8_t *target = pc_base + (voff << reloc.rsh);
if (target == loc.uc) {
// PC still in range to reify direct branch.
if (offset_in_jmp_range(diff)) {
if (offset_in_jmp_range(diff, flags)) {
// Target also in range: reify direct branch.
patch_jmp_offset(loc.ui, diff);
remove_pending_literal(_jit, reloc);
@ -425,7 +426,7 @@ jit_patch_there(jit_state_t* _jit, jit_reloc_t reloc, jit_pointer_t addr)
int32_t voff = read_jcc_offset(loc.ui);
uint8_t *target = pc_base + (voff << reloc.rsh);
if (target == loc.uc) {
if (offset_in_jcc_range(diff)) {
if (offset_in_jcc_range(diff, flags)) {
patch_jcc_offset(loc.ui, diff);
remove_pending_literal(_jit, reloc);
} else {