[Python-checkins] gh-96143: Clear instruction cache after mprotect call (#96476)
pablogsal
webhook-mailer at python.org
Thu Sep 8 07:04:50 EDT 2022
https://github.com/python/cpython/commit/3fedfcf19b86b4e95fd0b0fd089479ffad70e4c6
commit: 3fedfcf19b86b4e95fd0b0fd089479ffad70e4c6
branch: main
author: Pablo Galindo Salgado <Pablogsal at gmail.com>
committer: pablogsal <Pablogsal at gmail.com>
date: 2022-09-08T12:04:41+01:00
summary:
gh-96143: Clear instruction cache after mprotect call (#96476)
files:
M Objects/perf_trampoline.c
diff --git a/Objects/perf_trampoline.c b/Objects/perf_trampoline.c
index 2cbe3741f26f..161e0ef74cf1 100644
--- a/Objects/perf_trampoline.c
+++ b/Objects/perf_trampoline.c
@@ -149,6 +149,22 @@ typedef enum {
#include <sys/types.h>
#include <unistd.h>
+#if defined(__arm__) || defined(__arm64__) || defined(__aarch64__)
+#define PY_HAVE_INVALIDATE_ICACHE
+
+#if defined(__clang__) || defined(__GNUC__)
+extern void __clear_cache(void *, void*);
+#endif
+
+static void invalidate_icache(char* begin, char*end) {
+#if defined(__clang__) || defined(__GNUC__)
+ return __clear_cache(begin, end);
+#else
+ return;
+#endif
+}
+#endif
+
/* The function pointer is passed as last argument. The other three arguments
* are passed in the same order as the function requires. This results in
* shorter, more efficient ASM code for trampoline.
@@ -185,6 +201,7 @@ struct trampoline_api_st {
typedef struct trampoline_api_st trampoline_api_t;
+
static perf_status_t perf_status = PERF_STATUS_NO_INIT;
static Py_ssize_t extra_code_index = -1;
static code_arena_t *code_arena;
@@ -297,10 +314,6 @@ new_code_arena(void)
memcpy(memory + i * code_size, start, code_size * sizeof(char));
}
// Some systems may prevent us from creating executable code on the fly.
- // TODO: Call icache invalidation intrinsics if available:
- // __builtin___clear_cache/__clear_cache (depending if clang/gcc). This is
- // technically not necessary but we could be missing something so better be
- // safe.
int res = mprotect(memory, mem_size, PROT_READ | PROT_EXEC);
if (res == -1) {
PyErr_SetFromErrno(PyExc_OSError);
@@ -311,6 +324,12 @@ new_code_arena(void)
return -1;
}
+#ifdef PY_HAVE_INVALIDATE_ICACHE
+ // Before the JIT can run a block of code that has been emitted it must invalidate
+ // the instruction cache on some platforms like arm and aarch64.
+ invalidate_icache(memory, memory + mem_size);
+#endif
+
code_arena_t *new_arena = PyMem_RawCalloc(1, sizeof(code_arena_t));
if (new_arena == NULL) {
PyErr_NoMemory();
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