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Add bound check support for alloca on all targets

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stddef.h, tccdefs.h, tccgen.c, tests/boundtest.c, tests/tcctest.c:
- remove ifdef arround alloca

lib/Makefile:
- move alloca-bt.o to COMMON_O

lib/alloca-bt.S:
- add alloca bound check code for arm, arm64, riscv64

lib/alloca.S:
- check for leading underscore

tcc.h, libtcc.c:
- include arm64-asm.c instead of arm-asm.c for arm64

tcctok.h, tccasm.c:
- add simple reloc support (only for R_AARCH64_CALL26)
This commit is contained in:
herman ten brugge 2025-11-29 07:54:28 +01:00
parent fc424c9f7b
commit 6da45946ae
12 changed files with 142 additions and 59 deletions
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2
include/stddef.h
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@ -19,9 +19,7 @@ typedef union { long long __ll; long double __ld; } max_align_t;
#undef offsetof
#define offsetof(type, field) __builtin_offsetof(type, field)
#if defined __i386__ || defined __x86_64__
void *alloca(size_t size);
#endif
#endif

4
include/tccdefs.h
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@ -347,12 +347,8 @@
__MAYBE_REDIR(void*, calloc, (__SIZE_TYPE__, __SIZE_TYPE__))
__MAYBE_REDIR(void*, memalign, (__SIZE_TYPE__, __SIZE_TYPE__))
__MAYBE_REDIR(void, free, (void*))
#if defined __i386__ || defined __x86_64__
__BOTH(void*, alloca, (__SIZE_TYPE__))
void *alloca(__SIZE_TYPE__);
#else
__BUILTIN(void*, alloca, (__SIZE_TYPE__))
#endif
__BUILTIN(void, abort, (void))
__BOUND(void, longjmp, ())
#if !defined _WIN32

6
lib/Makefile
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@ -35,12 +35,12 @@ endif
XFLAGS += -I$(TOP)
I386_O = libtcc1.o alloca-bt.o $(COMMON_O)
X86_64_O = libtcc1.o alloca-bt.o $(COMMON_O)
I386_O = libtcc1.o $(COMMON_O)
X86_64_O = libtcc1.o $(COMMON_O)
ARM_O = libtcc1.o armeabi.o armflush.o $(COMMON_O)
ARM64_O = lib-arm64.o $(COMMON_O)
RISCV64_O = lib-arm64.o $(COMMON_O)
COMMON_O = stdatomic.o atomic.o builtin.o alloca.o
COMMON_O = stdatomic.o atomic.o builtin.o alloca.o alloca-bt.o
WIN_O = crt1.o crt1w.o wincrt1.o wincrt1w.o dllcrt1.o dllmain.o
LIN_O = dsohandle.o
OSX_O =

104
lib/alloca-bt.S
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@ -92,5 +92,109 @@ p3:
ret
#endif
/* ---------------------------------------------- */
#elif defined __arm__
.globl _(__bound_alloca)
_(__bound_alloca):
mov r1, r0
add r0, r0, #1
rsb sp, r0, sp
bic sp, sp, #7
mov r0, sp
push { lr }
bl _(__bound_new_region)
pop { lr }
mov r0, sp
mov pc, lr
/* ---------------------------------------------- */
#elif defined __aarch64__ || defined __arm64__
.globl _(__bound_alloca)
_(__bound_alloca):
#ifdef __TINYC__
.int 0xaa0003e1
.int 0x91004000
.int 0x927cec00
#ifdef _WIN32
.int 0xb4000160
.int 0xd2820002
.int 0xeb02001f
.int 0x540000c3
.int 0xcb2263e3
.int 0xf940007f
.int 0xcb2263ff
.int 0xcb020000
.int 0x17fffffa
.int 0xb4000040
#endif
.int 0xcb2063ff
.int 0x910003e0
.int 0xa9bf7bfd
.reloc ., R_AARCH64_CALL26, _(__bound_new_region)
.int 0x94000000
.int 0xa8c17bfd
.int 0x910003e0
.int 0xd65f03c0
#else
mov x1, x0
add x0, x0, #16 // Round up to 16-byte boundary
and x0, x0, #-16 // Ensure 16-byte alignment
#ifdef _WIN32
cbz x0, p100 // If size is 0, skip to return
// Windows requires page-wise allocation with stack probing
mov x2, #4096 // Page size = 4096 bytes
p101:
cmp x0, x2 // Compare remaining size with page size
b.lo p102 // If less than page, jump to remainder
// Probe first, then allocate
sub x3, sp, x2 // Calculate guard page address (sp - 4096)
ldr xzr, [x3] // Touch guard page FIRST
sub sp, sp, x2 // THEN allocate the page
sub x0, x0, x2 // Decrement remaining size
b p101 // Continue loop
p102:
// Allocate remaining bytes (less than one page)
cbz x0, p100 // If no remaining bytes, skip
sub sp, sp, x0 // Allocate remaining space
#else
// Non-Windows: simple one-time allocation
sub sp, sp, x0 // Allocate space on stack
#endif
p100:
mov x0, sp // Return allocated address
stp x29, x30, [sp, #-16]!
bl _(__bound_new_region)
ldp x29, x30, [sp], #16
mov x0, sp // Return allocated address
ret // Return to caller
#endif
/* ---------------------------------------------- */
#elif defined __riscv
.globl _(__bound_alloca)
_(__bound_alloca):
mv a1, a0
sub sp, sp, a0
addi sp, sp, -16
andi sp, sp, -16
add a0, sp, zero
addi sp,sp,-16
sd s0,0(sp)
sd ra,8(sp)
jal _(__bound_new_region)
ld s0,0(sp)
ld ra,8(sp)
addi sp,sp,16
add a0, sp, zero
ret
/* ---------------------------------------------- */
#endif

31
lib/alloca.S
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@ -70,25 +70,18 @@ p3:
/* ---------------------------------------------- */
#elif defined __arm__
.text
.align 2
.global alloca
.type alloca, %function
alloca:
.globl _(alloca)
_(alloca):
rsb sp, r0, sp
bic sp, sp, #7
mov r0, sp
mov pc, lr
.size alloca, .-alloca
/* ---------------------------------------------- */
#elif defined __aarch64__ || defined __arm64__
.text
.align 2
.global alloca
.type alloca, %function
alloca:
.globl _(alloca)
_(alloca):
#ifdef __TINYC__
.int 0x91003c00
.int 0x927cec00
@ -102,16 +95,16 @@ alloca:
.int 0xcb2163ff
.int 0xcb010000
.int 0x17fffffa
#endif
.int 0xb4000040
#endif
.int 0xcb2063ff
.int 0x910003e0
.int 0xd65f03c0
#else
add x0, x0, #15 // Round up to 16-byte boundary
and x0, x0, #-16 // Ensure 16-byte alignment
cbz x0, p100 // If size is 0, skip to return
#ifdef _WIN32
cbz x0, p100 // If size is 0, skip to return
// Windows requires page-wise allocation with stack probing
mov x1, #4096 // Page size = 4096 bytes
@ -140,20 +133,16 @@ p100:
mov x0, sp // Return allocated address
ret // Return to caller
#endif
.size alloca, .-alloca
/* ---------------------------------------------- */
#elif defined __riscv
.text
.align 2
.global alloca
.type alloca, %function
alloca:
.globl _(alloca)
_(alloca):
sub sp, sp, a0
addi sp, sp, -15
andi sp, sp, -16
add a0, sp, zero
ret
.size alloca, .-alloca
/* ---------------------------------------------- */
#endif

2
libtcc.c
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@ -40,7 +40,7 @@
#elif defined(TCC_TARGET_ARM64)
#include "arm64-gen.c"
#include "arm64-link.c"
#include "arm-asm.c"
#include "arm64-asm.c"
#elif defined(TCC_TARGET_C67)
#include "c67-gen.c"
#include "c67-link.c"

2
tcc.h
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@ -385,7 +385,7 @@ extern long double strtold (const char *__nptr, char **__endptr);
#elif defined TCC_TARGET_ARM64
# include "arm64-gen.c"
# include "arm64-link.c"
# include "arm-asm.c"
# include "arm64-asm.c"
#elif defined TCC_TARGET_C67
# define TCC_TARGET_COFF
# include "coff.h"

17
tccasm.c
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@ -984,6 +984,23 @@ static void asm_parse_directive(TCCState *s1, int global)
skip('@');
next();
break;
case TOK_ASMDIR_reloc:
{
ExprValue e;
next();
asm_expr(s1, &e);
skip(',');
#ifdef __aarch64__
if (strcmp(get_tok_str(tok, NULL), "R_AARCH64_CALL26"))
#endif
tcc_error("unimp: reloc '%s' unknown", get_tok_str(tok, NULL));
next();
skip(',');
greloca(cur_text_section, get_asm_sym(tok, NULL), e.v, R_AARCH64_CALL26, 0);
next();
}
break;
default:
tcc_error("unknown assembler directive '.%s'", get_tok_str(tok, NULL));
break;

2
tccgen.c
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@ -1701,10 +1701,8 @@ ST_FUNC void gbound_args(int nb_args)
gfunc_call(1);
func_bound_add_epilog = 1;
}
#if defined TCC_TARGET_I386 || defined TCC_TARGET_X86_64
if (v == TOK_alloca)
func_bound_add_epilog = 1;
#endif
#if TARGETOS_NetBSD
if (v == TOK_longjmp) /* undo rename to __longjmp14 */
sv->sym->asm_label = TOK___bound_longjmp;

3
tcctok.h
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@ -301,9 +301,7 @@
DEF(TOK___fixxfdi, "__fixxfdi")
#endif
#if defined TCC_TARGET_I386 || defined TCC_TARGET_X86_64
DEF(TOK_alloca, "alloca")
#endif
#if defined TCC_TARGET_PE
DEF(TOK___chkstk, "__chkstk")
@ -415,6 +413,7 @@
DEF_ASMDIR(long)
DEF_ASMDIR(int)
DEF_ASMDIR(symver)
DEF_ASMDIR(reloc)
DEF_ASMDIR(section) /* must be last directive */
#if defined TCC_TARGET_I386 || defined TCC_TARGET_X86_64

14
tests/boundtest.c
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@ -169,14 +169,6 @@ int test13(void)
return strlen(tab);
}
#if defined __i386__ || defined __x86_64__
#define allocf(x)
#else
#undef alloca
#define alloca(x) malloc(x)
#define allocf(x) free(x)
#endif
int test14(void)
{
char *p = alloca(TAB_SIZE);
@ -184,7 +176,6 @@ int test14(void)
memset(p, 'a', TAB_SIZE);
p[TAB_SIZE-1] = 0;
ret = strlen(p);
allocf(p);
return ret;
}
@ -196,7 +187,6 @@ int test15(void)
memset(p, 'a', TAB_SIZE);
p[TAB_SIZE-1] = 0;
ret = strlen(p);
allocf(p);
return ret;
}
@ -211,8 +201,6 @@ int test16()
/* Test alloca embedded in a larger expression */
printf("alloca : %s : %s\n", p, strcpy(q=alloca(strlen(demo)+1),demo) );
allocf(p);
allocf(q);
return 0;
}
@ -228,8 +216,6 @@ int test17()
/* Test alloca embedded in a larger expression */
printf("alloca : %s : %s\n", p, strcpy(q=alloca(strlen(demo)),demo) );
allocf(p);
allocf(q);
return 0;
}

4
tests/tcctest.c
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@ -2941,14 +2941,12 @@ void old_style_function_test(void)
void alloca_test()
{
#if defined __i386__ || defined __x86_64__ || defined __arm__
char *p = alloca(16);
strcpy(p,"123456789012345");
printf("alloca: p is %s\n", p);
char *demo = "This is only a test.\n";
/* Test alloca embedded in a larger expression */
printf("alloca: %s\n", strcpy(alloca(strlen(demo)+1),demo) );
#endif
}
void *bounds_checking_is_enabled()
@ -4208,7 +4206,6 @@ double get100 () { return 100.0; }
void callsave_test(void)
{
#if defined __i386__ || defined __x86_64__ || defined __arm__
int i, s; double *d; double t;
s = sizeof (double);
printf ("callsavetest: %d\n", s);
@ -4221,7 +4218,6 @@ void callsave_test(void)
generates a segfault. */
i = d[0] > get100 ();
printf ("%d\n", i);
#endif
}