From f7d9afea6cfb344021359ddd6101deb8f6e9cc76 Mon Sep 17 00:00:00 2001 From: James Hogan Date: Fri, 8 Jul 2016 14:05:26 +0100 Subject: [PATCH] MIPS: uasm: Handle low values in uasm_in_compat_space_p() uasm_in_compat_space_p() determines whether the given value is in the 32-bit compatibility part of the 64-bit address space, i.e. is in 32-bit sign-extended form, however it only handles the top half of the value space (corresponding to the kernel compatibility segments in the upper half of the address space). Since values < 2^31 (corresponding to the low 2GiB of the address space) can also be handled using 32-bit instructions (e.g. a LUI and ADDIU) rather than convoluted 64-bit immediate generation, rewrite it with a cast to check whether the address matches its 32-bit sign extended form. This allows UASM_i_LA to be used to generate arbitrary 32-bit immediates more efficiently on 64-bit CPUs, i.e. more like the li (load immediate) pseudo-instruction. For example this code to load the immediate (ST0_EXL | KSU_USER | ST0_BEV | ST0_KX) into k0 with UASM_i_LA(): lui k0,0x0 dsll k0,k0,0x10 daddiu k0,k0,64 dsll k0,k0,0x10 daddiu k0,k0,146 Changes to this more efficient version: lui k0,0x40 addiu k0,k0,146 Signed-off-by: James Hogan Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/13778/ Signed-off-by: Ralf Baechle --- arch/mips/mm/uasm.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/arch/mips/mm/uasm.c b/arch/mips/mm/uasm.c index ad718de..0b37340 100644 --- a/arch/mips/mm/uasm.c +++ b/arch/mips/mm/uasm.c @@ -370,11 +370,7 @@ UASM_EXPORT_SYMBOL(ISAFUNC(uasm_build_label)); int ISAFUNC(uasm_in_compat_space_p)(long addr) { /* Is this address in 32bit compat space? */ -#ifdef CONFIG_64BIT - return (((addr) & 0xffffffff00000000L) == 0xffffffff00000000L); -#else - return 1; -#endif + return addr == (int)addr; } UASM_EXPORT_SYMBOL(ISAFUNC(uasm_in_compat_space_p)); -- 2.7.4