From 075f6311af30b011eaa8e50341c06a9082a796a9 Mon Sep 17 00:00:00 2001 From: Tom Musta Date: Fri, 18 Oct 2013 12:07:10 -0500 Subject: [PATCH] powerpc: Fix Handler of Unaligned Load/Store Strings The alignment handler is incorrect for unaligned string instructions in little endian mode. These instructions access data as arrays of bytes and thus are endian neutral. However, the routine also handles the load/store multiple instructions, which are NOT endian neutral. This patch toggles the byte swapping flag for the string instructions in little endian builds. This effectively disables the byte swapping logic. Signed-off-by: Tom Musta Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/align.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c index 6e3f9772aaba..a3169a987b84 100644 --- a/arch/powerpc/kernel/align.c +++ b/arch/powerpc/kernel/align.c @@ -254,15 +254,20 @@ static int emulate_dcbz(struct pt_regs *regs, unsigned char __user *addr) * bottom 4 bytes of each register, and the loads clear the * top 4 bytes of the affected register. */ +#ifdef __BIG_ENDIAN__ #ifdef CONFIG_PPC64 #define REG_BYTE(rp, i) *((u8 *)((rp) + ((i) >> 2)) + ((i) & 3) + 4) #else #define REG_BYTE(rp, i) *((u8 *)(rp) + (i)) #endif +#endif + +#ifdef __LITTLE_ENDIAN__ +#define REG_BYTE(rp, i) (*(((u8 *)((rp) + ((i)>>2)) + ((i)&3)))) +#endif #define SWIZ_PTR(p) ((unsigned char __user *)((p) ^ swiz)) -#ifdef __BIG_ENDIAN__ static int emulate_multiple(struct pt_regs *regs, unsigned char __user *addr, unsigned int reg, unsigned int nb, unsigned int flags, unsigned int instr, @@ -304,6 +309,15 @@ static int emulate_multiple(struct pt_regs *regs, unsigned char __user *addr, nb0 = nb + reg * 4 - 128; nb = 128 - reg * 4; } +#ifdef __LITTLE_ENDIAN__ + /* + * String instructions are endian neutral but the code + * below is not. Force byte swapping on so that the + * effects of swizzling are undone in the load/store + * loops below. + */ + flags ^= SW; +#endif } else { /* lwm, stmw */ nb = (32 - reg) * 4; @@ -364,6 +378,7 @@ static int emulate_multiple(struct pt_regs *regs, unsigned char __user *addr, * Only POWER6 has these instructions, and it does true little-endian, * so we don't need the address swizzling. */ +#ifdef __BIG_ENDIAN__ static int emulate_fp_pair(unsigned char __user *addr, unsigned int reg, unsigned int flags) { @@ -882,13 +897,9 @@ int fix_alignment(struct pt_regs *regs) * function */ if (flags & M) { -#ifdef __BIG_ENDIAN__ PPC_WARN_ALIGNMENT(multiple, regs); return emulate_multiple(regs, addr, reg, nb, flags, instr, swiz); -#else - return -EFAULT; -#endif } /* Verify the address of the operand */