Historically SH-2 Linux (and originally uClinux) used a syscall
calling convention incompatible with the established SH-3/4 Linux ABI.
This choice was made because the trap range used by the existing ABI,
0x10-0x17, overlaps with the hardware exception/interrupt trap range
reserved by SH-2, and in particular, with the SH-2A divide-by-zero and
division-overflow exceptions.
Despite the documented syscall convention using the low bits of the
trap number to signal the number of arguments the kernel should
expect, no version of the kernel has ever used this information, nor
is it useful; all of the registers need to be saved anyway. Therefore,
it is possible to pick a new trap number, 0x1f, that is both supported
by all existing SH-3/4 kernels and unassigned as a hardware trap in
the SH-2 range. This makes it possible to produce SH-2 application
binaries that are forwards-compatible with running on SH-3/4 kernels
and to treat SH as a unified platform with varying ISA support levels
rather than multiple gratuitously-incompatible platforms.
This patch adjusts the range checking SH-2 and SH-2A kernels make for
the syscall trap to accept the range 0x1f-0x2f rather than just
0x20-0x2f. As a result, trap 0x1f now acts as a syscall for all SH
models.
Signed-off-by: Rich Felker <dalias@libc.org>
Future SH parts do not support any instruction but a nop in the rte delay
slot, so make the change for all offending parts. SH-5 is excluded from
this, and already has its own set of restrictions with regards to rte
delay slot handling.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This follows the sparc changes a439fe51a1.
Most of the moving about was done with Sam's directions at:
http://marc.info/?l=linux-sh&m=121724823706062&w=2
with subsequent hacking and fixups entirely my fault.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This patch is
By sh2
- Remove duplicate code
- Reduce stack usage
- Cleanup and little optimize
By sh2a
- Add missing handler(256 to 511)
- Use sh2a instructions handler
Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Kuninori Morimoto