Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753035Ab3J3At2 (ORCPT ); Tue, 29 Oct 2013 20:49:28 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:57187 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751381Ab3J3At0 (ORCPT ); Tue, 29 Oct 2013 20:49:26 -0400 Date: Wed, 30 Oct 2013 00:48:40 +0000 From: Will Deacon To: Jiang Liu Cc: Steven Rostedt , Catalin Marinas , Sandeepa Prabhu , Jiang Liu , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v5 4/7] arm64: introduce aarch64_insn_gen_{nop|branch_imm}() helper functions Message-ID: <20131030004840.GC25346@mudshark.cambridge.arm.com> References: <1382109602-27432-1-git-send-email-liuj97@gmail.com> <1382109602-27432-5-git-send-email-liuj97@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1382109602-27432-5-git-send-email-liuj97@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3214 Lines: 95 On Fri, Oct 18, 2013 at 04:19:58PM +0100, Jiang Liu wrote: > From: Jiang Liu > > Introduce aarch64_insn_gen_{nop|branch_imm}() helper functions, which > will be used to implement jump label on ARM64. > > Signed-off-by: Jiang Liu > Cc: Jiang Liu > --- > arch/arm64/include/asm/insn.h | 13 +++++++++++++ > arch/arm64/kernel/insn.c | 28 ++++++++++++++++++++++++++++ > 2 files changed, 41 insertions(+) > > diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h > index 8f94e48..ee4a60d 100644 > --- a/arch/arm64/include/asm/insn.h > +++ b/arch/arm64/include/asm/insn.h > @@ -96,9 +96,22 @@ static __always_inline void aarch64_insn_write(void *addr, u32 insn) > *(u32 *)addr = cpu_to_le32(insn); > } > > +static __always_inline u32 aarch64_insn_gen_hint(enum aarch64_insn_hint_op op) > +{ > + return aarch64_insn_get_hint_value() | op; What's the point in that helper function? Does it just return an immediate value (and are there are other users of it?). > +} > + > +static __always_inline u32 aarch64_insn_gen_nop(void) > +{ > + return aarch64_insn_gen_hint(AARCH64_INSN_HINT_NOP); > +} Either use plain old `inline' or write these as preprocessor macros. > + > enum aarch64_insn_encoding_class aarch64_get_insn_class(u32 insn); > u32 aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type, > u32 insn, u64 imm); > +u32 aarch64_insn_gen_branch_imm(unsigned long pc, unsigned long addr, > + bool link); > + > bool aarch64_insn_hotpatch_safe(u32 old_insn, u32 new_insn); > > int aarch64_insn_patch_text_nosync(void *addr, u32 insn); > diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c > index 886821f..f7498cc 100644 > --- a/arch/arm64/kernel/insn.c > +++ b/arch/arm64/kernel/insn.c > @@ -14,6 +14,7 @@ > * You should have received a copy of the GNU General Public License > * along with this program. If not, see . > */ > +#include > #include > #include > #include > @@ -233,3 +234,30 @@ u32 aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type, > > return insn; > } > + > +u32 aarch64_insn_gen_branch_imm(unsigned long pc, unsigned long addr, bool link) > +{ > + u32 insn; > + long offset; > + > + /* > + * PC: A 64-bit Program Counter holding the address of the current > + * instruction. A64 instructions may be word-aligned. > + */ > + BUG_ON((pc & 0x3) || (addr & 0x3)); > + > + /* > + * B/BL support [-128M, 128M) offset > + * ARM64 virtual address arrangement garantees all kernel and module Typo: `guarantees'. > + * texts are within +/-128M. > + */ > + offset = ((long)addr - (long)pc) >> 2; > + BUG_ON(abs(offset) > BIT(25) || offset == BIT(25)); I really struggle to follow this range checking. Why don't you just compare the absolute difference between addr and pc with SZ_128M? Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/