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ea0d55ae4b
We intend that EL0 exception handlers unmask all DAIF exceptions
before calling exit_to_user_mode().
When completing single-step of a suspended breakpoint, we do not call
local_daif_restore(DAIF_PROCCTX) before calling exit_to_user_mode(),
leaving all DAIF exceptions masked.
When pseudo-NMIs are not in use this is benign.
When pseudo-NMIs are in use, this is unsound. At this point interrupts
are masked by both DAIF.IF and PMR_EL1, and subsequent irq flag
manipulation may not work correctly. For example, a subsequent
local_irq_enable() within exit_to_user_mode_loop() will only unmask
interrupts via PMR_EL1 (leaving those masked via DAIF.IF), and
anything depending on interrupts being unmasked (e.g. delivery of
signals) will not work correctly.
This was detected by CONFIG_ARM64_DEBUG_PRIORITY_MASKING.
Move the call to `try_step_suspended_breakpoints()` outside of the check
so that interrupts can be unmasked even if we don't call the step handler.
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| 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 reStructuredText 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.