Commit Graph

14 Commits

Author SHA1 Message Date
Carl Shaw
2fc742f8d6 sh: Improve unwind info for signals
GCC does not issue unwind information for function epilogues.
Unfortunately we can catch a signal during an epilogue.  The signal
handler writes the current context and signal return code onto the stack
overwriting previous contents.  During unwinding, libgcc can try to
restore registers from the stack and restores corrupted ones. This can
lead to segmentation, misaligned access and sigbus faults.

For example, consider the following code:

    mov.l   r12,@-r15
    mov.l   r14,@-r15
    sts.l   pr,@-r15
    mov     r15,r14

    <do stuff>

    mov r14, r15
    lds.l @r15+, pr
	<<< SIGNAL HERE
    mov.l @r15+, r14
    mov.l @r15+, r12
    rts

Unwind is aware that pr was pushed to stack in prolog, so tries to
restore it.  Unfortunately it restores the last word of the signal
handler code placed on the stack by the kernel.

This patch tries to avoid the problem by adding a guard region on the
stack between where the function pushes data and where the signal handler
pushes its return code.  We probably don't see this problem often because
exception handling unwinding in an epilogue only occurs due to a pthread
cancel signal.  Also the kernel signal stack handler alignment of 8 bytes
could hide the occurance of this problem sometimes as the stack may not
be trampled at a particular required word.

This is not guaranteed to always work.  It relies on a frame pointer
existing for the function (so it can get the correct sp value) which is
not always the case for the SH4.

Modifications will also be made to libgcc for the case where there is no
fp.

Signed-off-by: Carl Shaw <carl.shaw@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2009-08-24 15:07:08 +09:00
Matt Fleming
9445571169 sh: Fix declaration of __kernel_sigreturn and __kernel_rt_sigreturn
GCC 4.5.0 complains about the declaration of variables
__kernel_sigreturn and __kernel_rt_sigreturn because they have type
void.  Correctly declare these symbols as functions to fix the
following error,

arch/sh/kernel/signal_32.c: In function 'setup_frame':
arch/sh/kernel/signal_32.c:368:14: error: taking address of expression of type 'void'
arch/sh/kernel/signal_32.c: In function 'setup_rt_frame':
arch/sh/kernel/signal_32.c:452:14: error: taking address of expression of type 'void'
make[1]: *** [arch/sh/kernel/signal_32.o] Error 1
make: *** [arch/sh/kernel] Error 2

Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2009-06-18 18:25:21 +09:00
Paul Mundt
03f07876df sh: Fix up spurious syscall restarting.
The T-bit manipulation for syscall error checking had the side effect of
spuriously returning ERESTART* errno values over EINTR. So, we simplify
the error checking a bit and leave the T-bit alone.

Reported-by: Kaz Kojima <kkojima@rr.iij4u.or.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2009-01-29 11:56:03 +09:00
Paul Mundt
94e2fb3d3e sh: Provide asm/syscall.h for SH-5.
This provides the asm/syscall.h implementation for sh64 parts.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-12-22 18:44:04 +09:00
Paul Mundt
1bec157a1f sh: Force pending restarted system calls to return -EINTR.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-09-24 14:37:35 +09:00
Paul Mundt
f8b890ab4c sh: Flag T-bit for syscall restart.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-09-12 22:08:20 +09:00
Paul Mundt
fa43972fab sh: fixup many sparse errors.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-09-08 10:35:04 +09:00
Paul Mundt
ab99c733ae sh: Make syscall tracer use tracehook notifiers, add TIF_NOTIFY_RESUME.
This follows the changes in commits:

7d6d637dac
4f72c4279e

on powerpc. Adding in TIF_NOTIFY_RESUME, and cleaning up the syscall
tracing to be more generic. This is an incremental step to turning
on tracehook, as well as unifying more of the ptrace and signal code
across the 32/64 split.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-08-02 04:39:33 +09:00
Stuart Menefy
f2fb4e4f64 sh: Conditionally re-enable IRQs in fault path.
The current kernel behaviour is to reenable interrupts unconditionally
when taking a page fault. This patch changes this to only enable them
if interrupts were previously enabled.

It also fixes a problem seen with this fix in place: the kernel previously
flushed the vsyscall page when handling a signal, which is not only
unncessary, but caused a possible sleep with interrupts disabled.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-07-28 18:10:33 +09:00
Chris Smith
09b5a10c19 sh: Optimized flush_icache_range() implementation.
Add implementation of flush_icache_range() suitable for signal handler
and kprobes. Remove flush_cache_sigtramp() and change signal.c to use
flush_icache_range().

Signed-off-by: Chris Smith <chris.smith@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-07-28 18:10:32 +09:00
Paul Mundt
3bc24a1a54 sh: Initial ELF FDPIC support.
This adds initial support for ELF FDPIC on MMU-less SH, as per version
0.2 of the ABI definition at:

	http://www.codesourcery.com/public/docs/sh-fdpic/sh-fdpic-abi.txt

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-07-28 18:10:28 +09:00
Paul Mundt
9bbafce2ee sh: Fix occasional FPU register corruption under preempt.
Presently with preempt enabled there's the possibility to be preempted
after the TIF_USEDFPU test and the register save, leading to bogus
state post-__switch_to(). Use an explicit preempt_disable()/enable()
pair around unlazy_fpu()/clear_fpu() to avoid this. Follows the x86
change.

Reported-by: Takuo Koguchi <takuo.koguchi.sw@hitachi.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-03-26 19:02:47 +09:00
Stuart Menefy
1efe4ce3ca sh: GUSA atomic rollback support.
This implements kernel-level atomic rollback built on top of gUSA,
as an alternative non-IRQ based atomicity method. This is generally
a faster method for platforms that are lacking the LL/SC pairs that
SH-4A and later use, and is only supportable on legacy cores.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-01-28 13:18:58 +09:00
Paul Mundt
f7a7b15344 sh: Move in the SH-5 signal trampoline impl.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2008-01-28 13:18:43 +09:00