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wasm2c: missing guard force_read error with escape hatch #2826

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Merged
shravanrn merged 1 commit into from
Aug 21, 2026
Merged

wasm2c: missing guard force_read error with escape hatch #2826

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28 changes: 18 additions & 10 deletions src/prebuilt/wasm2c_simd_source_declarations.cc
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Original file line number Diff line number Diff line change
@@ -1,6 +1,10 @@
const char* s_simd_source_declarations = R"w2c_template(#if WASM_RT_MEMCHECK_GUARD_PAGES
const char* s_simd_source_declarations = R"w2c_template(#if WASM_RT_MEMCHECK_BOUNDS_CHECK || \
)w2c_template"
R"w2c_template(#ifdef __GNUC__
R"w2c_template( WASM_RT_NONCONFORMING_ALLOW_OOB_READ_ELIMINATION
)w2c_template"
R"w2c_template(#define SIMD_FORCE_READ(var)
)w2c_template"
R"w2c_template(#elif defined(__GNUC__) && WASM_RT_MEMCHECK_GUARD_PAGES
)w2c_template"
R"w2c_template(#if defined(__x86_64__)
)w2c_template"
Expand All @@ -10,25 +14,29 @@ R"w2c_template(#elif defined(__aarch64__)
)w2c_template"
R"w2c_template(#define SIMD_FORCE_READ(var) __asm__("" ::"w"(var));
)w2c_template"
R"w2c_template(#elif defined(__riscv)
)w2c_template"
R"w2c_template(#define SIMD_FORCE_READ(var) __asm__("" ::"vr"(var));
)w2c_template"
R"w2c_template(#elif defined(__s390x__)
)w2c_template"
R"w2c_template(#define SIMD_FORCE_READ(var) __asm__("" ::"d"(var));
)w2c_template"
R"w2c_template(#endif
R"w2c_template(#else
)w2c_template"
R"w2c_template(#endif
R"w2c_template(#define SIMD_FORCE_READ(var) __asm__("" ::"f"(var));
)w2c_template"
R"w2c_template(#endif
)w2c_template"
R"w2c_template(
#ifndef SIMD_FORCE_READ
R"w2c_template(#else
)w2c_template"
R"w2c_template(#define SIMD_FORCE_READ(var)
R"w2c_template(#error \
)w2c_template"
R"w2c_template(#endif
R"w2c_template( "Guard page mode for Wasm not supported on this platform because SIMD_FORCE_READ could not be instantiated." \
)w2c_template"
R"w2c_template(
// TODO: equivalent constraint for ARM and other architectures
R"w2c_template( "Either enable specify -DWASM_RT_NONCONFORMING_ALLOW_OOB_READ_ELIMINATION=1 during compilation or use -DWASM_RT_MEMCHECK_BOUNDS_CHECK=1 to use bounds check mode"
)w2c_template"
R"w2c_template(#endif
)w2c_template"
R"w2c_template(
// The below SIMD operations copy to a local variable first as the
Expand Down
113 changes: 49 additions & 64 deletions src/prebuilt/wasm2c_source_declarations.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -311,120 +311,105 @@ R"w2c_template(#define MEMCHECK_DEFAULT32(mem, local_memory_size, a, t) \
)w2c_template"
R"w2c_template( WASM_RT_CHECK_BASE(mem);
)w2c_template"
R"w2c_template(
// When using guard pages, reads have to be immediately consumed so that OOB
)w2c_template"
R"w2c_template(// trap checks are applied in the right place, and not optimized away.
)w2c_template"
R"w2c_template(#ifdef __GNUC__
)w2c_template"
R"w2c_template(#define FORCE_READ_INT(var) __asm__("" ::"r"(var));
)w2c_template"
R"w2c_template(
#if defined(__i386__) || defined(__x86_64__)
)w2c_template"
R"w2c_template(#if defined(__SSE__)
R"w2c_template(#else
)w2c_template"
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "x"
R"w2c_template(#if WASM_RT_USE_LOCAL_MEMORY_BASE_SIZE_FOR_THIS_MODULE
)w2c_template"
R"w2c_template(#else // No SSE, old x87
R"w2c_template(#define MEMCHECK_DEFAULT32(mem, local_memory_size, a, t) \
)w2c_template"
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "f"
R"w2c_template( WASM_RT_CHECK_BASE(mem); \
)w2c_template"
R"w2c_template(#endif
R"w2c_template( if (UNLIKELY(a + (uint64_t)sizeof(t) > local_memory_size)) \
)w2c_template"
R"w2c_template(#elif (defined(__arm__) || defined(__aarch64__)) && defined(__ARM_FP) && \
R"w2c_template( TRAP(OOB);
)w2c_template"
R"w2c_template( ((__ARM_FP & 0x4) != 0)
R"w2c_template(#else
)w2c_template"
R"w2c_template(#ifdef __aarch64__
R"w2c_template(#define MEMCHECK_DEFAULT32(mem, local_memory_size, a, t) \
)w2c_template"
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "w"
R"w2c_template( WASM_RT_CHECK_BASE(mem); \
)w2c_template"
R"w2c_template(#else
R"w2c_template( if (UNLIKELY(a + (uint64_t)sizeof(t) > mem->size)) \
)w2c_template"
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "t"
R"w2c_template( TRAP(OOB);
)w2c_template"
R"w2c_template(#endif
)w2c_template"
R"w2c_template(#elif defined(__mips__) && defined(__clang__) && !defined(__mips_soft_float)
)w2c_template"
R"w2c_template(// Clang before v18 uses hard floats which has a different constraint
R"w2c_template(#endif
)w2c_template"
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "f"
R"w2c_template(
// MEMCHECK_GENERAL can be used for any memory
)w2c_template"
R"w2c_template(#elif (defined(__powerpc__) || defined(__ppc__) || defined(__PPC__)) || \
R"w2c_template(#define MEMCHECK_GENERAL(mem, a, t) \
)w2c_template"
R"w2c_template( !(defined(_SOFT_FLOAT) || defined(__NO_FPRS__))
R"w2c_template( WASM_RT_CHECK_BASE(mem); \
)w2c_template"
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "f"
R"w2c_template( RANGE_CHECK(mem, a, sizeof(t));
)w2c_template"
R"w2c_template(#elif defined(__riscv) && defined(__riscv_flen) && (__riscv_flen >= 32)
R"w2c_template(
// When using guard pages, reads have to be immediately consumed so that OOB
)w2c_template"
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "f"
R"w2c_template(// trap checks are applied in the right place, and not optimized away. This is
)w2c_template"
R"w2c_template(#elif defined(__s390__) || defined(__s390x__)
R"w2c_template(// done using FORCE_READ_INT/FORCE_READ_FLOAT
)w2c_template"
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "f"
R"w2c_template(#if WASM_RT_MEMCHECK_BOUNDS_CHECK || \
)w2c_template"
R"w2c_template(#else
R"w2c_template( WASM_RT_NONCONFORMING_ALLOW_OOB_READ_ELIMINATION
)w2c_template"
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "r"
R"w2c_template(#define FORCE_READ_INT(var)
)w2c_template"
R"w2c_template(#endif
R"w2c_template(#define FORCE_READ_FLOAT(var)
)w2c_template"
R"w2c_template(
#define FORCE_READ_FLOAT(var) __asm__("" ::FORCE_READ_FLOAT_CONSTRAINT(var));
R"w2c_template(#elif defined(__GNUC__) && WASM_RT_MEMCHECK_GUARD_PAGES
)w2c_template"
R"w2c_template(#endif
R"w2c_template(#define FORCE_READ_INT(var) __asm__("" ::"r"(var))
)w2c_template"
R"w2c_template(
#else
#if defined(__x86_64__) || defined(_M_X64)
)w2c_template"
R"w2c_template(#if WASM_RT_USE_LOCAL_MEMORY_BASE_SIZE_FOR_THIS_MODULE
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "x"
)w2c_template"
R"w2c_template(#define MEMCHECK_DEFAULT32(mem, local_memory_size, a, t) \
R"w2c_template(#elif defined(__aarch64__) && defined(__ARM_FP) && ((__ARM_FP & 0x4) != 0)
)w2c_template"
R"w2c_template( WASM_RT_CHECK_BASE(mem); \
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "w"
)w2c_template"
R"w2c_template( if (UNLIKELY(a + (uint64_t)sizeof(t) > local_memory_size)) \
R"w2c_template(#elif defined(__mips__) && defined(__clang__) && !defined(__mips_soft_float)
)w2c_template"
R"w2c_template( TRAP(OOB);
R"w2c_template(// Clang before v18 uses hard floats which has a different constraint
)w2c_template"
R"w2c_template(#else
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "f"
)w2c_template"
R"w2c_template(#define MEMCHECK_DEFAULT32(mem, local_memory_size, a, t) \
R"w2c_template(#elif (defined(__powerpc__) || defined(__ppc__) || defined(__PPC__)) && \
)w2c_template"
R"w2c_template( WASM_RT_CHECK_BASE(mem); \
R"w2c_template( !(defined(_SOFT_FLOAT) || defined(__NO_FPRS__))
)w2c_template"
R"w2c_template( if (UNLIKELY(a + (uint64_t)sizeof(t) > mem->size)) \
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "f"
)w2c_template"
R"w2c_template( TRAP(OOB);
R"w2c_template(#elif defined(__riscv) && defined(__riscv_flen) && (__riscv_flen >= 32)
)w2c_template"
R"w2c_template(#endif
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "f"
)w2c_template"
R"w2c_template(#endif
R"w2c_template(#elif defined(__s390__) || defined(__s390x__)
)w2c_template"
R"w2c_template(
// MEMCHECK_GENERAL can be used for any memory
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "f"
)w2c_template"
R"w2c_template(#define MEMCHECK_GENERAL(mem, a, t) \
R"w2c_template(#else
)w2c_template"
R"w2c_template( WASM_RT_CHECK_BASE(mem); \
R"w2c_template(#define FORCE_READ_FLOAT_CONSTRAINT "r"
)w2c_template"
R"w2c_template( RANGE_CHECK(mem, a, sizeof(t));
R"w2c_template(#endif
)w2c_template"
R"w2c_template(
#ifndef FORCE_READ_INT
#define FORCE_READ_FLOAT(var) __asm__("" ::FORCE_READ_FLOAT_CONSTRAINT(var))
)w2c_template"
R"w2c_template(#define FORCE_READ_INT(var)
R"w2c_template(#else
)w2c_template"
R"w2c_template(#endif
R"w2c_template(#error \
)w2c_template"
R"w2c_template(
#ifndef FORCE_READ_FLOAT
R"w2c_template( "Guard page mode for Wasm not supported on this platform because FORCE_READ_INT/FORCE_READ_FLOAT could not be instantiated." \
)w2c_template"
R"w2c_template(#define FORCE_READ_FLOAT(var)
R"w2c_template( "Either enable specify -DWASM_RT_NONCONFORMING_ALLOW_OOB_READ_ELIMINATION=1 during compilation or use -DWASM_RT_MEMCHECK_BOUNDS_CHECK=1 to use bounds check mode"
)w2c_template"
R"w2c_template(#endif
)w2c_template"
Expand Down
69 changes: 30 additions & 39 deletions src/template/wasm2c.declarations.c
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Original file line number Diff line number Diff line change
Expand Up @@ -165,42 +165,6 @@ static inline uint64_t checked_add_u64(uint64_t a, uint64_t b) {
#if WASM_RT_MEMCHECK_GUARD_PAGES
#define MEMCHECK_DEFAULT32(mem, local_memory_size, a, t) \
WASM_RT_CHECK_BASE(mem);

// When using guard pages, reads have to be immediately consumed so that OOB
// trap checks are applied in the right place, and not optimized away.
#ifdef __GNUC__
#define FORCE_READ_INT(var) __asm__("" ::"r"(var));

#if defined(__i386__) || defined(__x86_64__)
#if defined(__SSE__)
#define FORCE_READ_FLOAT_CONSTRAINT "x"
#else // No SSE, old x87
#define FORCE_READ_FLOAT_CONSTRAINT "f"
#endif
#elif (defined(__arm__) || defined(__aarch64__)) && defined(__ARM_FP) && \
((__ARM_FP & 0x4) != 0)
#ifdef __aarch64__
#define FORCE_READ_FLOAT_CONSTRAINT "w"
#else
#define FORCE_READ_FLOAT_CONSTRAINT "t"
#endif
#elif defined(__mips__) && defined(__clang__) && !defined(__mips_soft_float)
// Clang before v18 uses hard floats which has a different constraint
#define FORCE_READ_FLOAT_CONSTRAINT "f"
#elif (defined(__powerpc__) || defined(__ppc__) || defined(__PPC__)) || \
!(defined(_SOFT_FLOAT) || defined(__NO_FPRS__))
#define FORCE_READ_FLOAT_CONSTRAINT "f"
#elif defined(__riscv) && defined(__riscv_flen) && (__riscv_flen >= 32)
#define FORCE_READ_FLOAT_CONSTRAINT "f"
#elif defined(__s390__) || defined(__s390x__)
#define FORCE_READ_FLOAT_CONSTRAINT "f"
#else
#define FORCE_READ_FLOAT_CONSTRAINT "r"
#endif

#define FORCE_READ_FLOAT(var) __asm__("" ::FORCE_READ_FLOAT_CONSTRAINT(var));
#endif

#else
#if WASM_RT_USE_LOCAL_MEMORY_BASE_SIZE_FOR_THIS_MODULE
#define MEMCHECK_DEFAULT32(mem, local_memory_size, a, t) \
Expand All @@ -220,12 +184,39 @@ static inline uint64_t checked_add_u64(uint64_t a, uint64_t b) {
WASM_RT_CHECK_BASE(mem); \
RANGE_CHECK(mem, a, sizeof(t));

#ifndef FORCE_READ_INT
// When using guard pages, reads have to be immediately consumed so that OOB
// trap checks are applied in the right place, and not optimized away. This is
// done using FORCE_READ_INT/FORCE_READ_FLOAT
#if WASM_RT_MEMCHECK_BOUNDS_CHECK || \
WASM_RT_NONCONFORMING_ALLOW_OOB_READ_ELIMINATION
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#define FORCE_READ_INT(var)
#define FORCE_READ_FLOAT(var)
#elif defined(__GNUC__) && WASM_RT_MEMCHECK_GUARD_PAGES
#define FORCE_READ_INT(var) __asm__("" ::"r"(var))

#if defined(__x86_64__) || defined(_M_X64)
#define FORCE_READ_FLOAT_CONSTRAINT "x"
#elif defined(__aarch64__) && defined(__ARM_FP) && ((__ARM_FP & 0x4) != 0)
#define FORCE_READ_FLOAT_CONSTRAINT "w"
#elif defined(__mips__) && defined(__clang__) && !defined(__mips_soft_float)
// Clang before v18 uses hard floats which has a different constraint
#define FORCE_READ_FLOAT_CONSTRAINT "f"
#elif (defined(__powerpc__) || defined(__ppc__) || defined(__PPC__)) && \
!(defined(_SOFT_FLOAT) || defined(__NO_FPRS__))
#define FORCE_READ_FLOAT_CONSTRAINT "f"
#elif defined(__riscv) && defined(__riscv_flen) && (__riscv_flen >= 32)
#define FORCE_READ_FLOAT_CONSTRAINT "f"
#elif defined(__s390__) || defined(__s390x__)
#define FORCE_READ_FLOAT_CONSTRAINT "f"
#else
#define FORCE_READ_FLOAT_CONSTRAINT "r"
#endif

#ifndef FORCE_READ_FLOAT
#define FORCE_READ_FLOAT(var)
#define FORCE_READ_FLOAT(var) __asm__("" ::FORCE_READ_FLOAT_CONSTRAINT(var))
#else
#error \
"Guard page mode for Wasm not supported on this platform because FORCE_READ_INT/FORCE_READ_FLOAT could not be instantiated." \
"Either enable specify -DWASM_RT_NONCONFORMING_ALLOW_OOB_READ_ELIMINATION=1 during compilation or use -DWASM_RT_MEMCHECK_BOUNDS_CHECK=1 to use bounds check mode"
#endif

static inline void load_data(u8* dest, const u8* src, size_t n) {
Expand Down
21 changes: 12 additions & 9 deletions src/template/wasm2c_simd.declarations.c
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Original file line number Diff line number Diff line change
@@ -1,20 +1,23 @@
#if WASM_RT_MEMCHECK_GUARD_PAGES
#ifdef __GNUC__
#if WASM_RT_MEMCHECK_BOUNDS_CHECK || \
WASM_RT_NONCONFORMING_ALLOW_OOB_READ_ELIMINATION
#define SIMD_FORCE_READ(var)
#elif defined(__GNUC__) && WASM_RT_MEMCHECK_GUARD_PAGES
#if defined(__x86_64__)
#define SIMD_FORCE_READ(var) __asm__("" ::"x"(var));
#elif defined(__aarch64__)
#define SIMD_FORCE_READ(var) __asm__("" ::"w"(var));
#elif defined(__riscv)
#define SIMD_FORCE_READ(var) __asm__("" ::"vr"(var));
#elif defined(__s390x__)
#define SIMD_FORCE_READ(var) __asm__("" ::"d"(var));
#else
#define SIMD_FORCE_READ(var) __asm__("" ::"f"(var));
#endif
#else
#error \
"Guard page mode for Wasm not supported on this platform because SIMD_FORCE_READ could not be instantiated." \
"Either enable specify -DWASM_RT_NONCONFORMING_ALLOW_OOB_READ_ELIMINATION=1 during compilation or use -DWASM_RT_MEMCHECK_BOUNDS_CHECK=1 to use bounds check mode"
#endif
#endif

#ifndef SIMD_FORCE_READ
#define SIMD_FORCE_READ(var)
#endif

// TODO: equivalent constraint for ARM and other architectures

// The below SIMD operations copy to a local variable first as the
// MEM_ADDR_MEMOP maybe segment pointers if WASM_RT_USE_SEGUE_FOR_THIS_MODULE is
Expand Down
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