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author | James Hogan <james.hogan@imgtec.com> | 2016-07-08 14:05:26 +0100 |
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committer | Ralf Baechle <ralf@linux-mips.org> | 2016-07-24 13:15:28 +0200 |
commit | f7d9afea6cfb344021359ddd6101deb8f6e9cc76 (patch) | |
tree | 93deae3f6831df7174e0d65644e9de56426cbc7f /arch/mips/mm | |
parent | af1d8666c5f310c1a4c683b97d597ce3faae54b2 (diff) | |
download | linux-f7d9afea6cfb344021359ddd6101deb8f6e9cc76.tar.gz linux-f7d9afea6cfb344021359ddd6101deb8f6e9cc76.tar.bz2 linux-f7d9afea6cfb344021359ddd6101deb8f6e9cc76.zip |
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 <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13778/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/mm')
-rw-r--r-- | arch/mips/mm/uasm.c | 6 |
1 files changed, 1 insertions, 5 deletions
diff --git a/arch/mips/mm/uasm.c b/arch/mips/mm/uasm.c index ad718debc35a..0b373405766a 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)); |