[RFC] ppc64le: Enable emulation support for simple Load/Store instructions

emulate_step() uses a number of underlying kernel functions that were
initially not enabled for LE. This has been rectified since. So, fix
emulate_step() for LE for the corresponding instructions.

Reported-by: Anton Blanchard <redacted>
Signed-off-by: Ravi Bangoria <redacted>
---
Note: This patch only enables LOAD, STORE, LARX and STCX instructions.
      I'll send a subsequent patch for other types like LOAD_FP,
      LOAD_VMX etc.

 arch/powerpc/lib/sstep.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 3362299..82323ef 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c

@@ -1807,8 +1807,6 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 		goto instr_done;
 
 	case LARX:
-		if (regs->msr & MSR_LE)
-			return 0;
 		if (op.ea & (size - 1))
 			break;		/* can't handle misaligned */
 		err = -EFAULT;

@@ -1832,8 +1830,6 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 		goto ldst_done;
 
 	case STCX:
-		if (regs->msr & MSR_LE)
-			return 0;
 		if (op.ea & (size - 1))
 			break;		/* can't handle misaligned */
 		err = -EFAULT;

@@ -1859,8 +1855,6 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 		goto ldst_done;
 
 	case LOAD:
-		if (regs->msr & MSR_LE)
-			return 0;
 		err = read_mem(&regs->gpr[op.reg], op.ea, size, regs);
 		if (!err) {
 			if (op.type & SIGNEXT)

@@ -1913,8 +1907,6 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 		goto instr_done;
 
 	case STORE:
-		if (regs->msr & MSR_LE)
-			return 0;
 		if ((op.type & UPDATE) && size == sizeof(long) &&
 		    op.reg == 1 && op.update_reg == 1 &&
 		    !(regs->msr & MSR_PR) &&

-- 
1.8.3.1

On Thu, Oct 20, 2016 at 12:01:55PM +0530, Ravi Bangoria wrote:

emulate_step() uses a number of underlying kernel functions that were
initially not enabled for LE. This has been rectified since. So, fix
emulate_step() for LE for the corresponding instructions.

Reported-by: Anton Blanchard <redacted>
Signed-off-by: Ravi Bangoria <redacted>
---
Note: This patch only enables LOAD, STORE, LARX and STCX instructions.
      I'll send a subsequent patch for other types like LOAD_FP,
      LOAD_VMX etc.

 arch/powerpc/lib/sstep.c | 8 --------
 1 file changed, 8 deletions(-)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
for how to do this properly.

</formletter>