The frame pointer register is rarely used for that purpose on ARM and
applications that look at the contents of the jmp_buf may be relying
on reading an unencrypted value. For example, Ruby uses the contents
of jmp_buf to find the root set for garbage collection so relies on
this pointer value being unencrypted. Without this patch the Ruby
testsuite fails with a segmentation fault.
ports/ChangeLog.arm:
2013-01-14 Will Newton <will.newton@linaro.org>
* sysdeps/arm/__longjmp.S: Don't apply pointer encryption
to fp register.
* sysdeps/arm/setjmp.S: Likewise.
* sysdeps/arm/include/bits/setjmp.h (JMP_BUF_REGLIST): Add
fp to register list, remove a4.
* sysdeps/unix/sysv/linux/arm/sysdep.h (PTR_MANGLE_LOAD):
New macro.
Convert __longjmp code to allow building as Thumb.
ports/ChangeLog.arm:
2013-10-04 Will Newton <will.newton@linaro.org>
* sysdeps/arm/__longjmp.S (NO_THUMB): Remove define.
(__longjmp): Use Thumb supported instructions.
* sysdeps/unix/sysv/linux/arm/____longjmp_chk.S (NO_THUMB):
Remove define.
Add support for pointer encryption in glibc internal structures in C
and assembler code. Pointer encryption is a glibc security feature
described here:
https://sourceware.org/glibc/wiki/PointerEncryption
The ARM implementation uses global variables instead of thread pointer
relative accesses to get the value of the pointer encryption guard
because accessing the thread pointer can be very expensive on older
ARM cores.
ports/ChangeLog.arm:
2013-10-03 Will Newton <will.newton@linaro.org>
* sysdeps/arm/__longjmp.S (__longjmp): Demangle fp, sp
and lr when restoring register values.
* sysdeps/arm/include/bits/setjmp.h (JMP_BUF_REGLIST): Remove
sp and lr from list and replace fp with a4.
* sysdeps/arm/jmpbuf-unwind.h (_jmpbuf_sp): New function.
(_JMPBUF_UNWINDS_ADJ): Call _jmpbuf_sp.
* sysdeps/arm/setjmp.S (__sigsetjmp): Mangle fp, sp and lr
before storing register values.
* sysdeps/arm/sysdep.h (LDST_GLOBAL): New macro.
* sysdeps/unix/sysv/linux/arm/sysdep.h (PTR_MANGLE): New macro.
(PTR_DEMANGLE): Likewise. (PTR_MANGLE2): Likewise.
(PTR_DEMANGLE2): Likewise.
There was only one user. It's "condition" argument was used
for "ia" rather than an actual condition. The apcs26 syntax
is almost certainly not needed, given current binutils requirements.
Some routines are written with complex LDM/STM insns that cannot be
used in thumb mode, or are highly conditional requiring excessive
IT insns.
When a future patch goes in to enable thumb2 by default, this marker
will be used to override that default.
