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struct _Unwind_Exception alignment should not depend on compiler flags

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__attribute__((__aligned__)) selects an alignment that depends on
the micro-architecture selected by GCC flags.  Enabling vector
extensions may increase the allignment.  This is a problem when
building glibc as a collection of ELF multilibs with different
GCC flags because ld.so and libc.so/libpthread.so/&c may end up
with a different layout of struct pthread because of the
changing offset of its struct _Unwind_Exception field.

Tested-By: Matheus Castanho <msc@linux.ibm.com>
This commit is contained in:
Florian Weimer
2020-11-11 11:59:11 +01:00
parent 3d3316b1de
commit 30af7c7fa1
1 changed files with 14 additions and 8 deletions
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22
sysdeps/generic/unwind.h
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@@ -75,15 +75,21 @@ typedef void (*_Unwind_Exception_Cleanup_Fn) (_Unwind_Reason_Code,
struct _Unwind_Exception struct _Unwind_Exception
{ {
_Unwind_Exception_Class exception_class; union
_Unwind_Exception_Cleanup_Fn exception_cleanup; {
_Unwind_Word private_1; struct
_Unwind_Word private_2; {
_Unwind_Exception_Class exception_class;
_Unwind_Exception_Cleanup_Fn exception_cleanup;
_Unwind_Word private_1;
_Unwind_Word private_2;
};
/* @@@ The IA-64 ABI says that this structure must be double-word aligned. /* The IA-64 ABI says that this structure must be double-word aligned. */
Taking that literally does not make much sense generically. Instead we _Unwind_Word unwind_exception_align[2]
provide the maximum alignment required by any type for the machine. */ __attribute__ ((__aligned__ (2 * sizeof (_Unwind_Word))));
} __attribute__((__aligned__)); };
};
/* The ACTIONS argument to the personality routine is a bitwise OR of one /* The ACTIONS argument to the personality routine is a bitwise OR of one