From 15133cbf59d11da039d8df1eb8c4d3ce40ad851a Mon Sep 17 00:00:00 2001 From: Jeff Epler Date: Fri, 27 Aug 2021 09:02:03 -0500 Subject: [PATCH 1/2] gc.c: Avoid valgrind false positives. When you wish to use the valgrind memory analysis tool on micropython, you can arrange to define MICROPY_DEBUG_VALGRIND to enable use of special valgrind macros. For now, this only fixes `gc_get_ptr` so that it never emits the diagnostic "Conditional jump or move depends on uninitialised value(s)". Signed-off-by: Jeff Epler --- py/gc.c | 9 +++++++++ py/mpconfig.h | 5 +++++ 2 files changed, 14 insertions(+) diff --git a/py/gc.c b/py/gc.c index 8284c435ba94c..4d48a02a148b9 100644 --- a/py/gc.c +++ b/py/gc.c @@ -32,6 +32,10 @@ #include "py/gc.h" #include "py/runtime.h" +#if MICROPY_DEBUG_VALGRIND +#include +#endif + #if MICROPY_ENABLE_GC #if MICROPY_DEBUG_VERBOSE // print debugging info @@ -349,6 +353,11 @@ void gc_collect_start(void) { __attribute__((no_sanitize_address)) #endif static void *gc_get_ptr(void **ptrs, int i) { + #if MICROPY_DEBUG_VALGRIND + if (!VALGRIND_CHECK_MEM_IS_ADDRESSABLE(&ptrs[i], sizeof(*ptrs))) { + return NULL; + } + #endif return ptrs[i]; } diff --git a/py/mpconfig.h b/py/mpconfig.h index d40637dfaf6b4..f679f1e33f147 100644 --- a/py/mpconfig.h +++ b/py/mpconfig.h @@ -479,6 +479,11 @@ #define MICROPY_DEBUG_VM_STACK_OVERFLOW (0) #endif +// Whether to enable extra instrumentation for valgrind +#ifndef MICROPY_DEBUG_VALGRIND +#define MICROPY_DEBUG_VALGRIND (0) +#endif + /*****************************************************************************/ /* Optimisations */ From 5a162eb168b8518e20c04f12b5a3a8977d9d0020 Mon Sep 17 00:00:00 2001 From: Jeff Epler Date: Fri, 27 Aug 2021 09:04:32 -0500 Subject: [PATCH 2/2] gc.c: Ensure a gap of one byte before the finaliser table. .. or, for !MICROPY_ENABLE_FINALISER, before the first block of the pool. Closes: adafruit/circuitpython#5021 Closes: micropython/micropython#7116 Signed-off-by: Jeff Epler --- py/gc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/py/gc.c b/py/gc.c index 4d48a02a148b9..35bdf21fb2666 100644 --- a/py/gc.c +++ b/py/gc.c @@ -122,7 +122,7 @@ void gc_init(void *start, void *end) { // => T = A * (1 + BLOCKS_PER_ATB / BLOCKS_PER_FTB + BLOCKS_PER_ATB * BYTES_PER_BLOCK) size_t total_byte_len = (byte *)end - (byte *)start; #if MICROPY_ENABLE_FINALISER - MP_STATE_MEM(gc_alloc_table_byte_len) = total_byte_len * MP_BITS_PER_BYTE / (MP_BITS_PER_BYTE + MP_BITS_PER_BYTE * BLOCKS_PER_ATB / BLOCKS_PER_FTB + MP_BITS_PER_BYTE * BLOCKS_PER_ATB * BYTES_PER_BLOCK); + MP_STATE_MEM(gc_alloc_table_byte_len) = (total_byte_len - 1) * MP_BITS_PER_BYTE / (MP_BITS_PER_BYTE + MP_BITS_PER_BYTE * BLOCKS_PER_ATB / BLOCKS_PER_FTB + MP_BITS_PER_BYTE * BLOCKS_PER_ATB * BYTES_PER_BLOCK); #else MP_STATE_MEM(gc_alloc_table_byte_len) = total_byte_len / (1 + MP_BITS_PER_BYTE / 2 * BYTES_PER_BLOCK); #endif @@ -131,7 +131,7 @@ void gc_init(void *start, void *end) { #if MICROPY_ENABLE_FINALISER size_t gc_finaliser_table_byte_len = (MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB + BLOCKS_PER_FTB - 1) / BLOCKS_PER_FTB; - MP_STATE_MEM(gc_finaliser_table_start) = MP_STATE_MEM(gc_alloc_table_start) + MP_STATE_MEM(gc_alloc_table_byte_len); + MP_STATE_MEM(gc_finaliser_table_start) = MP_STATE_MEM(gc_alloc_table_start) + MP_STATE_MEM(gc_alloc_table_byte_len) + 1; #endif size_t gc_pool_block_len = MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB; pFad - Phonifier reborn

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