D62502, together with D62503 have broken the builds which have XML
support enabled. Reverting D62503 (r364355) fixed that, but has broken
has left some of the tests introduced by D62502 broken more or less
nondeternimistically (it depended on whether the system happens to place
the library list near unreadable pages of memory). I attempted to make a
partial fix for this in r364748, but Jan Kratochvil pointed out that
this reintroduces the problem which reverting D62503 was trying to
solve.
So instead, I back out the whole thing so we can get back to a clean
slate that works for everyone. We can figure out a way forward from
there.
This reverts r364748, r363772 and r363707.
llvm-svn: 364751
D62502 had a bug (visible only with D62503 reverted), where it would
error out if attempting to read a string from memory and the memory page
after the string happened to be unmapped.
This fixes the problem by checking for whether ReadMemory read *any*
bytes, instead of checking whether it returned an error. A greater
question is whether ReadMemory should even return an error if it read at
least one byte, but I'm leaving that for a separate patch.
llvm-svn: 364748
Summary:
This is the fifth patch to improve module loading in a series that started here (where I explain the motivation and solution): D62499
Reading strings with ReadMemory is really slow when reading the path of the shared library. This is because we don't know the length of the path so use PATH_MAX (4096) and these strings are actually super close to the boundary of an unreadable page. So even though we use process_vm_readv it will usually fail because the read size spans to the unreadable page and we then default to read the string word by word with ptrace.
This new function is very similar to another ReadCStringFromMemory that already exists in lldb that makes sure it never reads cross page boundaries and checks if we already read the entire string by finding '\0'.
I was able to reduce the GetLoadedSharedLibraries call from 30ms to 4ms (or something of that order).
Reviewers: clayborg, xiaobai, labath
Reviewed By: labath
Subscribers: emaste, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D62503
llvm-svn: 363750
Summary:
This is the fourth patch to improve module loading in a series that started here (where I explain the motivation and solution): D62499
Implement the `xfer:libraries-svr4` packet by adding a new function that generates the list and then in Handle_xfer I generate the XML for it. The XML is really simple so I'm just using string concatenation because I believe it's more readable than having to deal with a DOM api.
Reviewers: clayborg, xiaobai, labath
Reviewed By: labath
Subscribers: emaste, mgorny, srhines, krytarowski, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D62502
llvm-svn: 363707
Summary:
This is the third patch to improve module loading in a series that started here (where I explain the motivation and solution): D62499
Add functions to read the r_debug location to know where the linked list of loaded libraries are so I can generate the `xfer:libraries-svr4` packet.
I'm also using this function to implement `GetSharedLibraryInfoAddress` that was "not implemented" for linux.
Most of this code was inspired by the current ds2 implementation here: https://github.com/facebook/ds2/blob/master/Sources/Target/POSIX/ELFProcess.cpp.
Reviewers: clayborg, xiaobai, labath
Reviewed By: clayborg, labath
Subscribers: emaste, krytarowski, mgorny, lldb-commits
Tags: #lldb
Differential Revision: https://reviews.llvm.org/D62501
llvm-svn: 363458
Pavel Labath