[llvm] 88fdce5 - [lldb] Remove non address bits from memory read arguments
David Spickett via llvm-commits
llvm-commits at lists.llvm.org
Tue Jan 11 05:24:14 PST 2022
Author: David Spickett
Date: 2022-01-11T13:24:09Z
New Revision: 88fdce5be696c7ef992cffce9da9ec6895a1abfc
URL: https://github.com/llvm/llvm-project/commit/88fdce5be696c7ef992cffce9da9ec6895a1abfc
DIFF: https://github.com/llvm/llvm-project/commit/88fdce5be696c7ef992cffce9da9ec6895a1abfc.diff
LOG: [lldb] Remove non address bits from memory read arguments
Addresses on AArch64 can have top byte tags, memory tags and pointer
authentication signatures in the upper bits.
While testing memory tagging I found that memory read couldn't
read a range if the two addresses had different tags. The same
could apply to signed pointers given the right circumstance.
(lldb) memory read mte_buf_alt_tag mte_buf+16
error: end address (0x900fffff7ff8010) must be greater than the start
address (0xa00fffff7ff8000).
Or it would try to read a lot more memory than expected.
(lldb) memory read mte_buf mte_buf_alt_tag+16
error: Normally, 'memory read' will not read over 1024 bytes of data.
error: Please use --force to override this restriction just once.
error: or set target.max-memory-read-size if you will often need a
larger limit.
Fix this by removing non address bits before we calculate the read
range. A test is added for AArch64 Linux that confirms this by using
the top byte ignore feature.
This means that if you do read with a tagged pointer the output
does not include those tags. This is potentially confusing but I think
overall it's better that we don't pretend that we're reading memory
from a range that the process is unable to map.
(lldb) p ptr1
(char *) $4 = 0x3400fffffffff140 "\x80\xf1\xff\xff\xff\xff"
(lldb) p ptr2
(char *) $5 = 0x5600fffffffff140 "\x80\xf1\xff\xff\xff\xff"
(lldb) memory read ptr1 ptr2+16
0xfffffffff140: 80 f1 ff ff ff ff 00 00 38 70 bc f7 ff ff 00 00 ........8p......
Reviewed By: omjavaid, danielkiss
Differential Revision: https://reviews.llvm.org/D103626
Added:
lldb/test/API/linux/aarch64/tagged_memory_read/Makefile
lldb/test/API/linux/aarch64/tagged_memory_read/TestAArch64LinuxTaggedMemoryRead.py
lldb/test/API/linux/aarch64/tagged_memory_read/main.c
Modified:
lldb/source/Commands/CommandObjectMemory.cpp
llvm/docs/ReleaseNotes.rst
Removed:
################################################################################
diff --git a/lldb/source/Commands/CommandObjectMemory.cpp b/lldb/source/Commands/CommandObjectMemory.cpp
index 9df42f36fafdc..e59cd8028998a 100644
--- a/lldb/source/Commands/CommandObjectMemory.cpp
+++ b/lldb/source/Commands/CommandObjectMemory.cpp
@@ -23,6 +23,7 @@
#include "lldb/Interpreter/Options.h"
#include "lldb/Symbol/SymbolFile.h"
#include "lldb/Symbol/TypeList.h"
+#include "lldb/Target/ABI.h"
#include "lldb/Target/Language.h"
#include "lldb/Target/MemoryHistory.h"
#include "lldb/Target/MemoryRegionInfo.h"
@@ -590,9 +591,16 @@ class CommandObjectMemoryRead : public CommandObjectParsed {
return false;
}
+ ABISP abi = m_exe_ctx.GetProcessPtr()->GetABI();
+ if (abi)
+ addr = abi->FixDataAddress(addr);
+
if (argc == 2) {
lldb::addr_t end_addr = OptionArgParser::ToAddress(
&m_exe_ctx, command[1].ref(), LLDB_INVALID_ADDRESS, nullptr);
+ if (end_addr != LLDB_INVALID_ADDRESS && abi)
+ end_addr = abi->FixDataAddress(end_addr);
+
if (end_addr == LLDB_INVALID_ADDRESS) {
result.AppendError("invalid end address expression.");
result.AppendError(error.AsCString());
diff --git a/lldb/test/API/linux/aarch64/tagged_memory_read/Makefile b/lldb/test/API/linux/aarch64/tagged_memory_read/Makefile
new file mode 100644
index 0000000000000..c6ea179d22524
--- /dev/null
+++ b/lldb/test/API/linux/aarch64/tagged_memory_read/Makefile
@@ -0,0 +1,4 @@
+C_SOURCES := main.c
+CFLAGS_EXTRAS := -march=armv8.3-a
+
+include Makefile.rules
diff --git a/lldb/test/API/linux/aarch64/tagged_memory_read/TestAArch64LinuxTaggedMemoryRead.py b/lldb/test/API/linux/aarch64/tagged_memory_read/TestAArch64LinuxTaggedMemoryRead.py
new file mode 100644
index 0000000000000..2f55b951a7548
--- /dev/null
+++ b/lldb/test/API/linux/aarch64/tagged_memory_read/TestAArch64LinuxTaggedMemoryRead.py
@@ -0,0 +1,55 @@
+"""
+Test that "memory read" removes non address bits from
+memory read arguments.
+"""
+
+
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class AArch64LinuxTaggedMemoryReadTestCase(TestBase):
+
+ mydir = TestBase.compute_mydir(__file__)
+
+ NO_DEBUG_INFO_TESTCASE = True
+
+ # AArch64 Linux always enables top byte ignore
+ @skipUnlessArch("aarch64")
+ @skipUnlessPlatform(["linux"])
+ def test_tagged_memory_read(self):
+ self.build()
+ self.runCmd("file " + self.getBuildArtifact("a.out"), CURRENT_EXECUTABLE_SET)
+
+ lldbutil.run_break_set_by_file_and_line(self, "main.c",
+ line_number('main.c', '// Set break point at this line.'),
+ num_expected_locations=1)
+
+ self.runCmd("run", RUN_SUCCEEDED)
+
+ if self.process().GetState() == lldb.eStateExited:
+ self.fail("Test program failed to run.")
+
+ self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
+ substrs=['stopped',
+ 'stop reason = breakpoint'])
+
+ # If we do not remove non address bits, this can fail in two ways.
+ # 1. We attempt to read much more than 16 bytes, probably more than
+ # the default 1024 byte read size. Which will error.
+ # 2. We error because end address is < start address since end's
+ # tag is < start's tag.
+ #
+ # Each time we check that the printed line addresses do not include
+ # either of the tags we set. Those bits are a property of the
+ # pointer not of the memory it points to.
+ tagged_addr_pattern = "0x(34|46)[0-9A-Fa-f]{14}:.*"
+ self.expect("memory read ptr1 ptr2+16", patterns=[tagged_addr_pattern], matching=False)
+ # Check that the stored previous end address is stripped
+ self.expect("memory read", patterns=[tagged_addr_pattern], matching=False)
+ # Would fail if we don't remove non address bits because 0x56... > 0x34...
+ self.expect("memory read ptr2 ptr1+16", patterns=[tagged_addr_pattern], matching=False)
+ self.expect("memory read", patterns=[tagged_addr_pattern], matching=False)
diff --git a/lldb/test/API/linux/aarch64/tagged_memory_read/main.c b/lldb/test/API/linux/aarch64/tagged_memory_read/main.c
new file mode 100644
index 0000000000000..72ee30cef7869
--- /dev/null
+++ b/lldb/test/API/linux/aarch64/tagged_memory_read/main.c
@@ -0,0 +1,15 @@
+#include <stddef.h>
+
+static char *set_non_address_bits(char *ptr, size_t tag) {
+ // Set top byte tag (AArch64 Linux always enables top byte ignore)
+ return (char *)((size_t)ptr | (tag << 56));
+}
+
+int main(int argc, char const *argv[]) {
+ char buf[32];
+
+ char *ptr1 = set_non_address_bits(buf, 0x34);
+ char *ptr2 = set_non_address_bits(buf, 0x56);
+
+ return 0; // Set break point at this line.
+}
diff --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst
index c2af4200b9735..5825a6e81eb34 100644
--- a/llvm/docs/ReleaseNotes.rst
+++ b/llvm/docs/ReleaseNotes.rst
@@ -163,6 +163,9 @@ Changes to LLDB
* A change in Clang's type printing has changed the way LLDB names array types
(from ``int [N]`` to ``int[N]``) - LLDB pretty printer type name matching
code may need to be updated to handle this.
+* The ``memory read`` command now ignores non-address bits in start and end
+ addresses. In addition, non-address bits will not be shown in the addresses
+ in the output.
Changes to Sanitizers
---------------------
More information about the llvm-commits
mailing list