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MIPS: kernel: mips-r2-to-r6-emul: Add R2 emulator for MIPS R6

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MIPS R6 removed quite a few R2 instructions. However, there
is plenty of <R6 userland code so we add an in-kernel emulator
so we can still be able to execute all R2 userland out there.

The emulator comes with a handy debugfs under /mips/ directory
(r2-emul-stats) to provide some basic statistics of the
instructions that are being emulated.

Below are some statistics from booting a minimal buildroot image:

Instruction     Total   BDslot
------------------------------
movs            236969  0
hilo            56686   0
muls            55279   0
divs            10941   0
dsps            0       0
bops            1       0
traps           0       0
fpus            0       0
loads           214981  17
stores          103364  0
llsc            56898   0
dsemul          150418  0
jr              370158
bltzl           43
bgezl           1594
bltzll          0
bgezll          0
bltzal          39
bgezal          39
beql            14503
bnel            138741
blezl           0
bgtzl           3988

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
This commit is contained in:
Leonid Yegoshin
2014-12-03 15:47:03 +00:00
committed by Markos Chandras
parent b55b9e2715
commit b0a668fb20
8 changed files with 2518 additions and 5 deletions
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28
arch/mips/kernel/traps.c
View File

@@ -46,6 +46,7 @@
#include <asm/fpu.h>
#include <asm/fpu_emulator.h>
#include <asm/idle.h>
#include <asm/mips-r2-to-r6-emul.h>
#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
#include <asm/module.h>
@@ -837,7 +838,7 @@ out:
exception_exit(prev_state);
}
static void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
const char *str)
{
siginfo_t info;
@@ -1027,7 +1028,32 @@ asmlinkage void do_ri(struct pt_regs *regs)
unsigned int opcode = 0;
int status = -1;
/*
* Avoid any kernel code. Just emulate the R2 instruction
* as quickly as possible.
*/
if (mipsr2_emulation && cpu_has_mips_r6 &&
likely(user_mode(regs))) {
if (likely(get_user(opcode, epc) >= 0)) {
status = mipsr2_decoder(regs, opcode);
switch (status) {
case 0:
case SIGEMT:
return;
case SIGILL:
goto no_r2_instr;
default:
process_fpemu_return(status,
&current->thread.cp0_baduaddr);
return;
}
}
}
no_r2_instr:
prev_state = exception_enter();
if (notify_die(DIE_RI, "RI Fault", regs, 0, regs_to_trapnr(regs),
SIGILL) == NOTIFY_STOP)
goto out;