This "bpt_code" instruction was killed off in our development line a while
ago (the actual definition of bpt_code that is used is in kernel/traps.c)
but I didn't push it for 2.6.36 because it seemed harmless and I didn't
want to try to push more than absolutely necessary.

However, we recently fixed a bug in our gcc that had been causing
"-gdwarf2" not to be passed to the assembler, and passing this flag causes
an erroneous assembler failure in the presence of code in a data section,
sometimes.  While we'd like to track down the bug in the assembler,
we'd also like to make sure 2.6.36 builds with the current toolchain,
so I'm removing this dead code as well.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

This cut-and-paste bug was caused by rewriting the register dump
code to use only a single printk per line of output.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

During context switch, save and restore a couple of additional bits of
tilegx user state that can be persistently modified by userspace.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

Rather than just using pt_regs, it now contains the actual saved
state explicitly, similar to pt_regs.  By doing it this way, we
provide a cleaner API for userspace (or equivalently, we avoid the
need for libc to provide its own definition of sigcontext).

While we're at it, move PT_FLAGS_xxx to where they are not visible
from userspace.  And always pass siginfo and mcontext to signal
handlers, even if they claim they don't need it, since sometimes
they actually try to use it anyway in practice.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

The sys_execve() implementation was properly const-ified but not
the declaration, the syscall wrappers, or the compat version.
This change completes the constification process.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

Make do_execve() take a const filename pointer so that kernel_execve() compiles
correctly on ARM:

arch/arm/kernel/sys_arm.c:88: warning: passing argument 1 of 'do_execve' discards qualifiers from pointer target type

This also requires the argv and envp arguments to be consted twice, once for
the pointer array and once for the strings the array points to.  This is
because do_execve() passes a pointer to the filename (now const) to
copy_strings_kernel().  A simpler alternative would be to cast the filename
pointer in do_execve() when it's passed to copy_strings_kernel().

do_execve() may not change any of the strings it is passed as part of the argv
or envp lists as they are some of them in .rodata, so marking these strings as
const should be fine.

Further kernel_execve() and sys_execve() need to be changed to match.

This has been test built on x86_64, frv, arm and mips.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Until now, the tile architecture ABI for syscall return has just been
that r0 holds the return value, and an error is only signalled like it is
for kernel code, with a negative small number.

However, this means that in multiple places in userspace we end up writing
the same three-cycle idiom that tests for a small negative number for
error.  It seems cleaner to instead move that code into the kernel, and
set r1 to hold zero on success or errno on failure; previously, r1 was
just zeroed on return from the kernel (to avoid leaking kernel state).
This way a single conditional branch after the syscall is sufficient
to test for the failure case.  The number of cycles taken is the same,
but the error-checking code is in just one place, so total code size is
smaller, and random userspace syscall code is easier to understand.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

This functionality was stubbed out until recently.  Now we support our
normal backtracing API on TILE-Gx as well as on TILE64/TILEPro.
This change includes a tweak to the instruction encoding caused by
adding addxli for compat mode.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

First, the siginfo preamble wasn't quite right; we need to indicate
that we are padding up to 4 ints of preamble for 64-bit code, and
then for compat mode we need to pad differently, using only 3 ints.

Second, the C ABI requires a save area of two registers, not two
pointers, since in compat mode we have 64-bit registers all of which
we need to save, even though we only have 32-bit VAs.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

We were using the same 5-sec minsec for the clocksource and sched_clock
that we were using for the clock_event_device.  For the clock_event_device
that's exactly right since it has a short maximum countdown time.
But for sched_clock we want to avoid wraparound when converting from
ticks to nsec over a much longer window, so we force a shift of 10.
And for clocksource it seems dodgy to use a 5-sec minsec as well, so we
copy some other platforms and force a shift of 22.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>