Skip to content

Commit

Permalink
[lldb] Ignore non-address bits in "memory find" arguments
Browse files Browse the repository at this point in the history
This removes the non-address bits before we try to use
the addresses.

Meaning that when results are shown, those results won't
show non-address bits either. This follows what "memory read"
has done. On the grounds that non-address bits are a property
of a pointer, not the memory pointed to.

I've added testing and merged the find and read tests into one
file.

Note that there are no API side changes because "memory find"
does not have an equivalent API call.

Reviewed By: omjavaid

Differential Revision: https://reviews.llvm.org/D117299
  • Loading branch information
DavidSpickett committed Jan 24, 2022
1 parent aa50b93 commit 7d19566
Show file tree
Hide file tree
Showing 4 changed files with 46 additions and 8 deletions.
6 changes: 6 additions & 0 deletions lldb/source/Commands/CommandObjectMemory.cpp
Expand Up @@ -1032,6 +1032,12 @@ class CommandObjectMemoryFind : public CommandObjectParsed {
return false;
}

ABISP abi = m_exe_ctx.GetProcessPtr()->GetABI();
if (abi) {
low_addr = abi->FixDataAddress(low_addr);
high_addr = abi->FixDataAddress(high_addr);
}

if (high_addr <= low_addr) {
result.AppendError(
"starting address must be smaller than ending address");
Expand Down
@@ -1,6 +1,9 @@
"""
Test that "memory read" removes non address bits from
memory read arguments.
Test that "memory read" and "memory find" remove non address bits from
address arguments.
These tests use the top byte ignore feature of AArch64. Which Linux
always enables.
"""


Expand All @@ -17,10 +20,7 @@ class AArch64LinuxTaggedMemoryReadTestCase(TestBase):

NO_DEBUG_INFO_TESTCASE = True

# AArch64 Linux always enables top byte ignore
@skipUnlessArch("aarch64")
@skipUnlessPlatform(["linux"])
def test_tagged_memory_read(self):
def setup_test(self):
self.build()
self.runCmd("file " + self.getBuildArtifact("a.out"), CURRENT_EXECUTABLE_SET)

Expand All @@ -37,6 +37,11 @@ def test_tagged_memory_read(self):
substrs=['stopped',
'stop reason = breakpoint'])

@skipUnlessArch("aarch64")
@skipUnlessPlatform(["linux"])
def test_tagged_memory_read(self):
self.setup_test()

# 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.
Expand All @@ -53,3 +58,26 @@ def test_tagged_memory_read(self):
# 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)

@skipUnlessArch("aarch64")
@skipUnlessPlatform(["linux"])
def test_tagged_memory_find(self):
self.setup_test()

# If memory find doesn't remove non-address bits one of two
# things happen.
# 1. It tries to search a gigantic amount of memory.
# We're not going to test for this because a failure
# would take a very long time and perhaps even find the
# target value randomly.
# 2. It thinks high address <= low address, which we check below.

self.runCmd("memory find -s '?' ptr2 ptr1+32")

self.assertTrue(self.res.Succeeded())
out = self.res.GetOutput()
# memory find does not fail when it doesn't find the data.
# First check we actually got something.
self.assertRegexpMatches(out, "data found at location: 0x[0-9A-Fa-f]+")
# Then that the location found does not display the tag bits.
self.assertNotRegexpMatches(out, "data found at location: 0x(34|56)[0-9A-Fa-f]+")
Expand Up @@ -5,11 +5,15 @@ static char *set_non_address_bits(char *ptr, size_t tag) {
return (char *)((size_t)ptr | (tag << 56));
}

int main(int argc, char const *argv[]) {
char buf[32];
// Global to zero init
char buf[32];

int main(int argc, char const *argv[]) {
char *ptr1 = set_non_address_bits(buf, 0x34);
char *ptr2 = set_non_address_bits(buf, 0x56);

// Target value for "memory find"
buf[15] = '?';

return 0; // Set break point at this line.
}

0 comments on commit 7d19566

Please sign in to comment.