dc2cf4ca86
segbase is the address of .eh_frame_hdr and table_data is segbase plus
the header size. find_proc_info computes segbase as `map->start +
segbase - map->pgoff` which is wrong when
* .eh_frame_hdr and .text are in different PT_LOAD program headers
* and their p_vaddr difference does not equal their p_offset difference
Since 10.0, ld.lld's default --rosegment -z noseparate-code layout has
such R and RX PT_LOAD program headers.
ld.lld (default) => perf report fails to unwind `perf record
--call-graph dwarf` recorded data
ld.lld --no-rosegment => ok (trivial, no R PT_LOAD)
ld.lld -z separate-code => ok but by luck: there are two PT_LOAD but
their p_vaddr difference equals p_offset difference
ld.bfd -z noseparate-code => ok (trivial, no R PT_LOAD)
ld.bfd -z separate-code (default for Linux/x86) => ok but by luck:
there are two PT_LOAD but their p_vaddr difference equals p_offset
difference
To fix the issue, compute segbase as dso's base address plus
PT_GNU_EH_FRAME's p_vaddr. The base address is computed by iterating
over all dso-associated maps and then subtract the first PT_LOAD p_vaddr
(the minimum guaranteed by generic ABI) from the minimum address.
In libunwind, find_proc_info transitively called by unw_step is cached,
so the iteration overhead is acceptable.
Reported-by: Sebastian Ullrich <sebasti@nullri.ch>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: llvm@lists.linux.dev
Link: https://github.com/ClangBuiltLinux/linux/issues/1646
Link: https://lore.kernel.org/r/20220527182039.673248-1-maskray@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
|
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.