ARM: Add SystemTap probes to longjmp and setjmp.

Now the ARM port implements pointer encryption for jmpbufs, gdb needs
a SystemTap probe point in longjmp to determine the target PC of
a call to longjmp. This patch implements the probe point in longjmp
and a similar probe point in setjmp.

In order to have all the appropriate registers available to pass to the
probe this reorders the layout of jmpbuf, putting the sp and lr registers
at the start rather than the end, allowing them to be read and
written sequentially.

Tested on armv7, no new failures in the glibc testsuite and confirmed
that this fixes the gdb.base/longjmp.exp failures in the gdb testsuite.

ChangeLog:

2014-02-25  Will Newton  <will.newton@linaro.org>

	* sysdeps/arm/__longjmp.S: Include stap-probe.h.
	(__longjmp): Restore sp and lr before restoring callee
	saved registers.  Add longjmp and longjmp_target
	SystemTap probe point.
	* sysdeps/arm/bits/setjmp.h (__jmp_buf): Update comment.
	* sysdeps/arm/include/bits/setjmp.h (__JMP_BUF_SP):
	Define to zero to match jmpbuf layout.
	* sysdeps/arm/setjmp.S: Include stap-probe.h.
	(__sigsetjmp): Save sp and lr before saving callee
	saved registers.  Add setjmp SystemTap probe point.

1 files changed, 2 insertions, 3 deletions

diff --git a/sysdeps/arm/bits/setjmp.h b/sysdeps/arm/bits/setjmp.h
index 41423b2c3b..a68735993a 100644
--- a/sysdeps/arm/bits/setjmp.h
+++ b/sysdeps/arm/bits/setjmp.h
@@ -28,9 +28,8 @@
 /* The exact set of registers saved may depend on the particular core
    in use, as some coprocessor registers may need to be saved.  The C
    Library ABI requires that the buffer be 8-byte aligned, and
-   recommends that the buffer contain 64 words.  The first 27 words
-   are occupied by v1-v6, sl, fp, sp, pc, and d8-d15.  (Note that
-   d8-15 require 17 words, due to the use of fstmx.)  */
+   recommends that the buffer contain 64 words.  The first 26 words
+   are occupied by sp, lr, v1-v6, sl, fp, and d8-d15.  */
 typedef int __jmp_buf[64] __attribute__((__aligned__ (8)));
 #endif