MIPS: kernel: Prepare the JR instruction for emulation on MIPS R6
The MIPS R6 JR instruction is an alias to the JALR one, so it may
need emulation for non-R6 userlands.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
diff --git a/arch/mips/include/asm/branch.h b/arch/mips/include/asm/branch.h
index de781cf..2894ea5 100644
--- a/arch/mips/include/asm/branch.h
+++ b/arch/mips/include/asm/branch.h
@@ -13,6 +13,9 @@
#include <asm/ptrace.h>
#include <asm/inst.h>
+static int mipsr2_emulation = 0;
+#define NO_R6EMU (cpu_has_mips_r6 && !mipsr2_emulation)
+
extern int __isa_exception_epc(struct pt_regs *regs);
extern int __compute_return_epc(struct pt_regs *regs);
extern int __compute_return_epc_for_insn(struct pt_regs *regs,
diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c
index 4d7d99d..5736949 100644
--- a/arch/mips/kernel/branch.c
+++ b/arch/mips/kernel/branch.c
@@ -417,6 +417,8 @@
regs->regs[insn.r_format.rd] = epc + 8;
/* Fall through */
case jr_op:
+ if (NO_R6EMU && insn.r_format.func == jr_op)
+ goto sigill_r6;
regs->cp0_epc = regs->regs[insn.r_format.rs];
break;
}
@@ -477,7 +479,7 @@
case bposge32_op:
if (!cpu_has_dsp)
- goto sigill;
+ goto sigill_dsp;
dspcontrol = rddsp(0x01);
@@ -631,10 +633,15 @@
return ret;
-sigill:
+sigill_dsp:
printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm);
force_sig(SIGBUS, current);
return -EFAULT;
+sigill_r6:
+ pr_info("%s: R2 branch but r2-to-r6 emulator is not preset - sending SIGILL.\n",
+ current->comm);
+ force_sig(SIGILL, current);
+ return -EFAULT;
}
EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn);
diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
index 9dfcd7f..9bf8211 100644
--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -448,6 +448,9 @@
dec_insn.next_pc_inc;
/* Fall through */
case jr_op:
+ /* For R6, JR already emulated in jalr_op */
+ if (NO_R6EMU && insn.r_format.opcode == jr_op)
+ break;
*contpc = regs->regs[insn.r_format.rs];
return 1;
}