mirror of
https://gitee.com/openharmony/third_party_jsoncpp
synced 2024-12-04 05:26:28 +00:00
127 lines
4.6 KiB
Diff
127 lines
4.6 KiB
Diff
From 42e892d96e47b1f6e29844cc705e148ec4856448 Mon Sep 17 00:00:00 2001
|
|
From: Jessica Clarke <jrtc27@jrtc27.com>
|
|
Date: Wed, 12 Jan 2022 21:27:16 +0000
|
|
Subject: [PATCH] Use default rather than hard-coded 8 for maximum aggregate
|
|
member alignment (#1378)
|
|
|
|
On CHERI, and thus Arm's Morello prototype, pointers are represented as
|
|
hardware capabilities. These capabilities are comprised of not just an
|
|
integer address, as is the representation for traditional pointers, but
|
|
also bounds, permissions and other metadata, plus a tag bit used as the
|
|
validity bit, which provides fine-grained spatial and referential safety
|
|
for C and C++ in hardware. This tag bit is not part of the data itself
|
|
and is instead kept on the side, flowing with the capability between
|
|
registers and the memory subsystem, and any attempt to amplify the
|
|
privilege of or corrupt a capability clears this tag (or, in some cases,
|
|
traps), rendering them impossible to forge; you can only create
|
|
capabilities that are (possibly trivial) subsets of existing ones.
|
|
|
|
When the capability is stored in memory, this tag bit needs to be
|
|
preserved, which is done through the use of tagged memory. Every
|
|
capability-sized word gains an additional non-addressable (from the
|
|
CPU's perspective; depending on the implementation the tag bits may be
|
|
stored in a small block of memory carved out of normal DRAM that the CPU
|
|
is blocked from accessing) bit. This means that capabilities can only be
|
|
stored to aligned locations; attempting to store them to unaligned
|
|
locations will trap with an alignment fault or, if you end up using a
|
|
memcpy call, will copy the raw bytes of the capability's representation
|
|
but lose the tag, so when it is eventually loaded back as a capability
|
|
and dereferenced it will fault.
|
|
|
|
Since, on 64-bit architectures, our capabilities, used to implement C
|
|
language pointers, are 128-bit quantities, this means they need 16-byte
|
|
alignment. Currently the various #pragma pack directives, used to work
|
|
around (extremely broken and bogus) code that includes jsoncpp in a
|
|
context where the maximum alignment has been overridden, hard-code 8 as
|
|
the maximum alignment to use, and so do not sufficiently align CHERI /
|
|
Morello capabilities on 64-bit architectures. On Windows x64, the
|
|
default is also not 8 but 16 (ARM64 is supposedly 8), so this is
|
|
slightly dodgy to do there too, but in practice likely not an issue so
|
|
long as you don't use any 128-bit types there.
|
|
|
|
Instead of hard-coding a width, use a directive that resets the packing
|
|
back to the default. Unfortunately, whilst GCC and Clang both accept
|
|
using #pragma pack(push, 0) as shorthand like for any non-zero value,
|
|
MSVC does not, so this needs to be two directives.
|
|
---
|
|
include/json/allocator.h | 3 ++-
|
|
include/json/json_features.h | 3 ++-
|
|
include/json/reader.h | 3 ++-
|
|
include/json/value.h | 3 ++-
|
|
include/json/writer.h | 3 ++-
|
|
5 files changed, 10 insertions(+), 5 deletions(-)
|
|
|
|
diff --git a/include/json/allocator.h b/include/json/allocator.h
|
|
index 95ef8a5..7540642 100644
|
|
--- a/include/json/allocator.h
|
|
+++ b/include/json/allocator.h
|
|
@@ -9,7 +9,8 @@
|
|
#include <cstring>
|
|
#include <memory>
|
|
|
|
-#pragma pack(push, 8)
|
|
+#pragma pack(push)
|
|
+#pragma pack()
|
|
|
|
namespace Json {
|
|
template <typename T> class SecureAllocator {
|
|
diff --git a/include/json/json_features.h b/include/json/json_features.h
|
|
index 7c7e9f5..e4a61d6 100644
|
|
--- a/include/json/json_features.h
|
|
+++ b/include/json/json_features.h
|
|
@@ -10,7 +10,8 @@
|
|
#include "forwards.h"
|
|
#endif // if !defined(JSON_IS_AMALGAMATION)
|
|
|
|
-#pragma pack(push, 8)
|
|
+#pragma pack(push)
|
|
+#pragma pack()
|
|
|
|
namespace Json {
|
|
|
|
diff --git a/include/json/reader.h b/include/json/reader.h
|
|
index be0d767..46975d8 100644
|
|
--- a/include/json/reader.h
|
|
+++ b/include/json/reader.h
|
|
@@ -23,7 +23,8 @@
|
|
#pragma warning(disable : 4251)
|
|
#endif // if defined(JSONCPP_DISABLE_DLL_INTERFACE_WARNING)
|
|
|
|
-#pragma pack(push, 8)
|
|
+#pragma pack(push)
|
|
+#pragma pack()
|
|
|
|
namespace Json {
|
|
|
|
diff --git a/include/json/value.h b/include/json/value.h
|
|
index 0edeb05..57ecb13 100644
|
|
--- a/include/json/value.h
|
|
+++ b/include/json/value.h
|
|
@@ -53,7 +53,8 @@
|
|
#pragma warning(disable : 4251 4275)
|
|
#endif // if defined(JSONCPP_DISABLE_DLL_INTERFACE_WARNING)
|
|
|
|
-#pragma pack(push, 8)
|
|
+#pragma pack(push)
|
|
+#pragma pack()
|
|
|
|
/** \brief JSON (JavaScript Object Notation).
|
|
*/
|
|
diff --git a/include/json/writer.h b/include/json/writer.h
|
|
index 03f9906..7d8cf4d 100644
|
|
--- a/include/json/writer.h
|
|
+++ b/include/json/writer.h
|
|
@@ -20,7 +20,8 @@
|
|
#pragma warning(disable : 4251)
|
|
#endif // if defined(JSONCPP_DISABLE_DLL_INTERFACE_WARNING)
|
|
|
|
-#pragma pack(push, 8)
|
|
+#pragma pack(push)
|
|
+#pragma pack()
|
|
|
|
namespace Json {
|
|
|
|
--
|
|
2.42.0.windows.2
|
|
|