Commit e698b966 authored by Paul Mackerras's avatar Paul Mackerras Committed by Benjamin Herrenschmidt
Browse files

powerpc: Fix bugs in emulate_step() 



This fixes some bugs in emulate_step().  First, the setting of the carry
bit for the arithmetic right-shift instructions was not correct on 64-bit
machines because we were masking with a mask of type int rather than
unsigned long.  Secondly, the sld (shift left doubleword) instruction was
using the wrong instruction field for the register containing the shift
count.

Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent bd6ba351

arch/powerpc/lib/sstep.c

+5 −5
Original line number Diff line number Diff line
@@ -1198,7 +1198,7 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr) 
			sh = regs->gpr[rb] & 0x3f;

			ival = (signed int) regs->gpr[rd];

			regs->gpr[ra] = ival >> (sh < 32 ? sh : 31);

			if (ival < 0 && (sh >= 32 || (ival & ((1 << sh) - 1)) != 0))

			if (ival < 0 && (sh >= 32 || (ival & ((1ul << sh) - 1)) != 0))

				regs->xer |= XER_CA;

			else

				regs->xer &= ~XER_CA;
@@ -1208,7 +1208,7 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr) 
			sh = rb;

			ival = (signed int) regs->gpr[rd];

			regs->gpr[ra] = ival >> sh;

			if (ival < 0 && (ival & ((1 << sh) - 1)) != 0)

			if (ival < 0 && (ival & ((1ul << sh) - 1)) != 0)

				regs->xer |= XER_CA;

			else

				regs->xer &= ~XER_CA;
@@ -1216,7 +1216,7 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr) 


#ifdef __powerpc64__

		case 27:	/* sld */

			sh = regs->gpr[rd] & 0x7f;

			sh = regs->gpr[rb] & 0x7f;

			if (sh < 64)

				regs->gpr[ra] = regs->gpr[rd] << sh;

			else
@@ -1235,7 +1235,7 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr) 
			sh = regs->gpr[rb] & 0x7f;

			ival = (signed long int) regs->gpr[rd];

			regs->gpr[ra] = ival >> (sh < 64 ? sh : 63);

			if (ival < 0 && (sh >= 64 || (ival & ((1 << sh) - 1)) != 0))

			if (ival < 0 && (sh >= 64 || (ival & ((1ul << sh) - 1)) != 0))

				regs->xer |= XER_CA;

			else

				regs->xer &= ~XER_CA;
@@ -1246,7 +1246,7 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr) 
			sh = rb | ((instr & 2) << 4);

			ival = (signed long int) regs->gpr[rd];

			regs->gpr[ra] = ival >> sh;

			if (ival < 0 && (ival & ((1 << sh) - 1)) != 0)

			if (ival < 0 && (ival & ((1ul << sh) - 1)) != 0)

				regs->xer |= XER_CA;

			else

				regs->xer &= ~XER_CA;

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