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py: Make sure that static emg-exc-buffer is aligned to size of mp_obj_t.

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This buffer is used to allocate objects temporarily, and such objects
require that their underlying memory be correctly aligned for their data
type.  Aligning for mp_obj_t should be sufficient for emergency exceptions,
but in general the memory buffer should aligned to the maximum alignment of
the machine (eg on a 32-bit machine with mp_obj_t being 4 bytes, a double
may not be correctly aligned).

This patch fixes a bug for certain nan-boxing builds, where mp_obj_t is 8
bytes and must be aligned to 8 bytes (even though the machine is 32 bit).
This commit is contained in:
Damien George 2017-04-10 16:02:56 +10:00
parent b87432b8fb
commit ee86de1f1a
2 changed files with 5 additions and 5 deletions
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4
py/mpstate.h
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@ -120,8 +120,8 @@ typedef struct _mp_state_vm_t {
// memory for exception arguments if we can't allocate RAM // memory for exception arguments if we can't allocate RAM
#if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF #if MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
#if MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE > 0 #if MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE > 0
// statically allocated buf // statically allocated buf (needs to be aligned to mp_obj_t)
byte mp_emergency_exception_buf[MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE]; mp_obj_t mp_emergency_exception_buf[MICROPY_EMERGENCY_EXCEPTION_BUF_SIZE / sizeof(mp_obj_t)];
#else #else
// dynamically allocated buf // dynamically allocated buf
byte *mp_emergency_exception_buf; byte *mp_emergency_exception_buf;

6
py/objexcept.c
View File

@ -348,7 +348,7 @@ mp_obj_t mp_obj_new_exception_msg_varg(const mp_obj_type_t *exc_type, const char
tuple->items[0] = MP_OBJ_FROM_PTR(str); tuple->items[0] = MP_OBJ_FROM_PTR(str);
byte *str_data = (byte *)&str[1]; byte *str_data = (byte *)&str[1];
uint max_len = MP_STATE_VM(mp_emergency_exception_buf) + mp_emergency_exception_buf_size size_t max_len = (byte*)MP_STATE_VM(mp_emergency_exception_buf) + mp_emergency_exception_buf_size
- str_data; - str_data;
vstr_t vstr; vstr_t vstr;
@ -366,14 +366,14 @@ mp_obj_t mp_obj_new_exception_msg_varg(const mp_obj_type_t *exc_type, const char
o->args = tuple; o->args = tuple;
uint offset = &str_data[str->len] - MP_STATE_VM(mp_emergency_exception_buf); size_t offset = &str_data[str->len] - (byte*)MP_STATE_VM(mp_emergency_exception_buf);
offset += sizeof(void *) - 1; offset += sizeof(void *) - 1;
offset &= ~(sizeof(void *) - 1); offset &= ~(sizeof(void *) - 1);
if ((mp_emergency_exception_buf_size - offset) > (sizeof(o->traceback_data[0]) * 3)) { if ((mp_emergency_exception_buf_size - offset) > (sizeof(o->traceback_data[0]) * 3)) {
// We have room to store some traceback. // We have room to store some traceback.
o->traceback_data = (size_t*)((byte *)MP_STATE_VM(mp_emergency_exception_buf) + offset); o->traceback_data = (size_t*)((byte *)MP_STATE_VM(mp_emergency_exception_buf) + offset);
o->traceback_alloc = (MP_STATE_VM(mp_emergency_exception_buf) + mp_emergency_exception_buf_size - (byte *)o->traceback_data) / sizeof(o->traceback_data[0]); o->traceback_alloc = ((byte*)MP_STATE_VM(mp_emergency_exception_buf) + mp_emergency_exception_buf_size - (byte *)o->traceback_data) / sizeof(o->traceback_data[0]);
o->traceback_len = 0; o->traceback_len = 0;
} }
} }