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Fix stack overwrite on structure return 

The common code to move a returned structure packed into
registers into memory on the caller side didn't take the
register size into account when allocating local storage,
so sometimes that lead to stack overwrites (e.g. in 73_arm64.c),
on x86_64.  This fixes it by generally making gfunc_sret also return
the register size.
master
Michael Matz 2015-03-09 00:19:59 +01:00
parent d73b488401
commit 50899e30ab
7 changed files with 26 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arm-gen.c
View File

@ -869,18 +869,20 @@ int floats_in_core_regs(SValue *sval)
/* Return the number of registers needed to return the struct, or 0 if
returning via struct pointer. */
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *ret_align) {
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *ret_align, int *regsize) {
#ifdef TCC_ARM_EABI
int size, align;
size = type_size(vt, &align);
if (float_abi == ARM_HARD_FLOAT && !variadic &&
(is_float(vt->t) || is_hgen_float_aggr(vt))) {
*ret_align = 8;
*regsize = 8;
ret->ref = NULL;
ret->t = VT_DOUBLE;
return (size + 7) >> 3;
} else if (size <= 4) {
*ret_align = 4;
*regsize = 4;
ret->ref = NULL;
ret->t = VT_INT;
return 1;
@ -1255,7 +1257,7 @@ void gfunc_call(int nb_args)
void gfunc_prolog(CType *func_type)
{
Sym *sym,*sym2;
int n, nf, size, align, struct_ret = 0;
int n, nf, size, align, rs, struct_ret = 0;
int addr, pn, sn; /* pn=core, sn=stack */
CType ret_type;
@ -1269,7 +1271,7 @@ void gfunc_prolog(CType *func_type)
n = nf = 0;
if ((func_vt.t & VT_BTYPE) == VT_STRUCT &&
!gfunc_sret(&func_vt, func_var, &ret_type, &align))
!gfunc_sret(&func_vt, func_var, &ret_type, &align, &rs))
{
n++;
struct_ret = 1;

2
arm64-gen.c
View File

@ -1196,7 +1196,7 @@ ST_FUNC void gen_va_arg(CType *t)
}
}
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *align)
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *align, int *regsize)
{
return 0;
}

2
c67-gen.c
View File

@ -1881,7 +1881,7 @@ static void gcall_or_jmp(int is_jmp)
/* Return the number of registers needed to return the struct, or 0 if
returning via struct pointer. */
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *ret_align) {
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *ret_align, int *regsize) {
*ret_align = 1; // Never have to re-align return values for x86-64
return 0;
}

3
i386-gen.c
View File

@ -376,12 +376,13 @@ static uint8_t fastcallw_regs[2] = { TREG_ECX, TREG_EDX };
/* Return the number of registers needed to return the struct, or 0 if
returning via struct pointer. */
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *ret_align)
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *ret_align, int *regsize)
{
#ifdef TCC_TARGET_PE
int size, align;
*ret_align = 1; // Never have to re-align return values for x86
*regsize = 4;
size = type_size(vt, &align);
if (size > 8) {
return 0;

2
tcc.h
View File

@ -1327,7 +1327,7 @@ ST_FUNC void gsym_addr(int t, int a);
ST_FUNC void gsym(int t);
ST_FUNC void load(int r, SValue *sv);
ST_FUNC void store(int r, SValue *v);
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *align);
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *align, int *regsize);
ST_FUNC void gfunc_call(int nb_args);
ST_FUNC void gfunc_prolog(CType *func_type);
ST_FUNC void gfunc_epilog(void);

20
tccgen.c
View File

@ -4153,7 +4153,7 @@ ST_FUNC void unary(void)
} else if (tok == '(') {
SValue ret;
Sym *sa;
int nb_args, ret_nregs, ret_align, variadic;
int nb_args, ret_nregs, ret_align, regsize, variadic;
/* function call */
if ((vtop->type.t & VT_BTYPE) != VT_FUNC) {
@ -4179,7 +4179,7 @@ ST_FUNC void unary(void)
if ((s->type.t & VT_BTYPE) == VT_STRUCT) {
variadic = (s->c == FUNC_ELLIPSIS);
ret_nregs = gfunc_sret(&s->type, variadic, &ret.type,
&ret_align);
&ret_align, &regsize);
if (!ret_nregs) {
/* get some space for the returned structure */
size = type_size(&s->type, &align);
@ -4259,6 +4259,10 @@ ST_FUNC void unary(void)
int addr, offset;
size = type_size(&s->type, &align);
/* We're writing whole regs often, make sure there's enough
space. Assume register size is power of 2. */
if (regsize > align)
align = regsize;
loc = (loc - size) & -align;
addr = loc;
offset = 0;
@ -4269,8 +4273,7 @@ ST_FUNC void unary(void)
vtop--;
if (--ret_nregs == 0)
break;
/* XXX: compatible with arm only: ret_align == register_size */
offset += ret_align;
offset += regsize;
}
vset(&s->type, VT_LOCAL | VT_LVAL, addr);
}
@ -4850,9 +4853,9 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
#else
if ((func_vt.t & VT_BTYPE) == VT_STRUCT) {
CType type, ret_type;
int ret_align, ret_nregs;
int ret_align, ret_nregs, regsize;
ret_nregs = gfunc_sret(&func_vt, func_var, &ret_type,
&ret_align);
&ret_align, &regsize);
if (0 == ret_nregs) {
/* if returning structure, must copy it to implicit
first pointer arg location */
@ -4890,9 +4893,10 @@ static void block(int *bsym, int *csym, int *case_sym, int *def_sym,
/* We assume that when a structure is returned in multiple
registers, their classes are consecutive values of the
suite s(n) = 2^n */
/* XXX This seems confused, if r == 0, this never
changes r. */
r <<= 1;
/* XXX: compatible with arm only: ret_align == register_size */
vtop->c.i += ret_align;
vtop->c.i += regsize;
vtop->r = VT_LOCAL | VT_LVAL;
}
}

6
x86_64-gen.c
View File

@ -662,9 +662,10 @@ void gen_offs_sp(int b, int r, int d)
/* Return the number of registers needed to return the struct, or 0 if
returning via struct pointer. */
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *ret_align)
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *ret_align, int *regsize)
{
int size, align;
*regsize = 8;
*ret_align = 1; // Never have to re-align return values for x86-64
size = type_size(vt, &align);
ret->ref = NULL;
@ -1069,10 +1070,11 @@ ST_FUNC int classify_x86_64_va_arg(CType *ty)
/* Return the number of registers needed to return the struct, or 0 if
returning via struct pointer. */
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *ret_align)
ST_FUNC int gfunc_sret(CType *vt, int variadic, CType *ret, int *ret_align, int *regsize)
{
int size, align, reg_count;
*ret_align = 1; // Never have to re-align return values for x86-64
*regsize = 8;
return (classify_x86_64_arg(vt, ret, &size, &align, &reg_count) != x86_64_mode_memory);
}