d0acc76a49
find_extable_entry_size() is completely broken. It has awesome comments
about how to calculate sizeof(struct exception_table_entry).
It was based on these assumptions:
- struct exception_table_entry has two fields
- both of the fields have the same size
Then, we came up with this equation:
(offset of the second field) * 2 == (size of struct)
It was true for all architectures when commit 52dc0595d540 ("modpost:
handle relocations mismatch in __ex_table.") was applied.
Our mathematics broke when commit 548acf19234d ("x86/mm: Expand the
exception table logic to allow new handling options") introduced the
third field.
Now, the definition of exception_table_entry is highly arch-dependent.
For x86, sizeof(struct exception_table_entry) is apparently 12, but
find_extable_entry_size() sets extable_entry_size to 8.
I could fix it, but I do not see much value in this code.
extable_entry_size is used just for selecting a slightly different
error message.
If the first field ("insn") references to a non-executable section,
The relocation at %s+0x%lx references
section "%s" which is not executable, IOW
it is not possible for the kernel to fault
at that address. Something is seriously wrong
and should be fixed.
If the second field ("fixup") references to a non-executable section,
The relocation at %s+0x%lx references
section "%s" which is not executable, IOW
the kernel will fault if it ever tries to
jump to it. Something is seriously wrong
and should be fixed.
Merge the two error messages rather than adding even more complexity.
Change fatal() to error() to make it continue running and catch more
possible errors.
Fixes: 548acf19234d ("x86/mm: Expand the exception table logic to allow new handling options")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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.