Patch from Nicolas Pitre
For a while we wanted to change the way syscalls were called on ARM.
Instead of encoding the syscall number in the swi instruction which
requires reading back the instruction from memory to extract that number
and polluting the data cache, it was decided that simply storing the
syscall number into r7 would be more efficient. Since this represents
an ABI change then making that change at the same time as EABI support
is the right thing to do.
It is now expected that EABI user space binaries put the syscall number
into r7 and use "swi 0" to call the kernel. Syscall register argument
are also expected to have "EABI arrangement" i.e. 64-bit arguments
should be put in a pair of registers from an even register number.
Example with long ftruncate64(unsigned int fd, loff_t length):
legacy ABI:
- put fd into r0
- put length into r1-r2
- use "swi #(0x900000 + 194)" to call the kernel
new ARM EABI:
- put fd into r0
- put length into r2-r3 (skipping over r1)
- put 194 into r7
- use "swi 0" to call the kernel
Note that it is important to use 0 for the swi argument as backward
compatibility with legacy ABI user space relies on this.
The syscall macros in asm-arm/unistd.h were also updated to support
both ABIs and implement the right call method automatically.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Rather than providing more wrappers for 6-arg syscalls, arrange for
them to be supported as standard. This just means that we always
store the 6th argument on the stack, rather than in the wrappers.
This means we eliminate the wrappers for:
* sys_futex
* sys_arm_fadvise64_64
* sys_mbind
* sys_ipc
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from Daniel Jacobowitz
After delivering a signal (creating its stack frame) we must check for
additional pending unblocked signals before returning to userspace.
Otherwise signals may be delayed past the next syscall or reschedule.
Once that was fixed it became obvious that the ARM signal mask manipulation
was broken. It was a little bit broken before the recent SA_NODEFER
changes, and then very broken after them. We must block the requested
signals before starting the handler or the same signal can be delivered
again before the handler even gets a chance to run.
Signed-off-by: Daniel Jacobowitz <dan@codesourcery.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from Nicolas Pitre
Either no one is using an ARM710 with recent kernels, or all ARM710s
still in use are not afflicted by this swi bug. Nevertheless, the code
to work around the ARM710 swi bug is itself currently buggy since it
uses r8 as a pointer to S_PC while in fact it holds the spsr content
these days. Fix that, and simplify the code as well.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from George G. Davis
As pointed out be Matthew Klahn <MKLAHN@motorola.com>, some sys_ipc()
call options require six args, e.g. SEMTIMEDOP. This patch adds an ARM sys_ipc_wrapper to save the sys_ipc() 'fifth' arg on the stack.
Signed-off-by: George G. Davis <gdavis@mvista.com>
arch/arm/kernel/calls.S | 2 +-
arch/arm/kernel/entry-common.S | 5 +++++
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from Nicolas Pitre
The prototype for sys_fadvise64_64() is:
long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
The argument list is therefore as follows on legacy ABI:
fd: type int (r0)
offset: type long long (r1-r2)
len: type long long (r3-sp[0])
advice: type int (sp[4])
With EABI this becomes:
fd: type int (r0)
offset: type long long (r2-r3)
len: type long long (sp[0]-sp[4])
advice: type int (sp[8])
Not only do we have ABI differences here, but the EABI version requires
one additional word on the syscall stack.
To avoid the ABI mismatch and the extra stack space required with EABI
this syscall is now defined with a different argument ordering
on ARM as follows:
long sys_arm_fadvise64_64(int fd, int advice, loff_t offset, loff_t len)
This gives us the following ABI independent argument distribution:
fd: type int (r0)
advice: type int (r1)
offset: type long long (r2-r3)
len: type long long (sp[0]-sp[4])
Now, since the syscall entry code takes care of 5 registers only by
default including the store of r4 to the stack, we need a wrapper to
store r5 to the stack as well. Because that wrapper was missing and was
always required this means that sys_fadvise64_64 never worked on ARM and
therefore we can safely reuse its syscall number for our new
sys_arm_fadvise64_64 interface.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Nicolas Pitre