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85 lines
2.4 KiB
Diff
85 lines
2.4 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Daniel Micay <danielmicay@gmail.com>
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Date: Wed, 2 Dec 2015 23:37:28 -0500
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Subject: [PATCH] switch pthread_atfork handler allocation to mmap
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Signed-off-by: anupritaisno1 <www.anuprita804@gmail.com>
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---
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libc/bionic/pthread_atfork.cpp | 35 ++++++++++++++++++++++++++++------
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1 file changed, 29 insertions(+), 6 deletions(-)
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diff --git a/libc/bionic/pthread_atfork.cpp b/libc/bionic/pthread_atfork.cpp
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index 0dcabdfb2..6306052ee 100644
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--- a/libc/bionic/pthread_atfork.cpp
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+++ b/libc/bionic/pthread_atfork.cpp
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@@ -29,6 +29,9 @@
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#include <errno.h>
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#include <pthread.h>
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#include <stdlib.h>
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+#include <sys/mman.h>
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+#include <sys/prctl.h>
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+#include <unistd.h>
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#include "platform/bionic/macros.h"
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@@ -43,6 +46,8 @@ struct atfork_t {
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void* dso_handle;
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};
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+static atfork_t* pool;
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+
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class atfork_list_t {
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public:
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constexpr atfork_list_t() : first_(nullptr), last_(nullptr) {}
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@@ -101,7 +106,8 @@ class atfork_list_t {
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last_ = entry->prev;
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}
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- free(entry);
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+ entry->next = pool;
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+ pool = entry;
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}
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atfork_t* first_;
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@@ -154,18 +160,35 @@ void __bionic_atfork_run_parent() {
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// __register_atfork is the name used by glibc
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extern "C" int __register_atfork(void (*prepare)(void), void (*parent)(void),
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void(*child)(void), void* dso) {
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- atfork_t* entry = reinterpret_cast<atfork_t*>(malloc(sizeof(atfork_t)));
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- if (entry == nullptr) {
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- return ENOMEM;
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+ pthread_mutex_lock(&g_atfork_list_mutex);
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+
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+ if (!pool) {
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+ size_t page_size = getpagesize();
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+ char* page = static_cast<char*>(mmap(NULL, page_size, PROT_READ|PROT_WRITE,
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+ MAP_ANONYMOUS|MAP_PRIVATE, -1, 0));
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+ if (page == MAP_FAILED) {
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+ pthread_mutex_unlock(&g_atfork_list_mutex);
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+ return ENOMEM;
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+ }
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+
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+ prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, page, page_size,
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+ "atfork handlers");
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+
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+ for (char* it = page; it < page + page_size - sizeof(atfork_t); it += sizeof(atfork_t)) {
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+ atfork_t* node = reinterpret_cast<atfork_t*>(it);
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+ node->next = pool;
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+ pool = node;
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+ }
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}
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+ atfork_t* entry = pool;
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+ pool = entry->next;
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+
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entry->prepare = prepare;
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entry->parent = parent;
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entry->child = child;
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entry->dso_handle = dso;
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- pthread_mutex_lock(&g_atfork_list_mutex);
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-
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g_atfork_list.push_back(entry);
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pthread_mutex_unlock(&g_atfork_list_mutex);
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