From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F882C4338F for ; Wed, 4 Aug 2021 17:32:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 204A660EE9 for ; Wed, 4 Aug 2021 17:32:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237620AbhHDRck (ORCPT ); Wed, 4 Aug 2021 13:32:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41072 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229934AbhHDRci (ORCPT ); Wed, 4 Aug 2021 13:32:38 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E2473C0613D5 for ; Wed, 4 Aug 2021 10:32:25 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id n192-20020a25dac90000b029054c59edf217so3593368ybf.3 for ; Wed, 04 Aug 2021 10:32:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=/j6yv6+Ku7KXNVVOYpvwLhxyPAj/+OpFFq2HsmTelKU=; b=aEvu1PvvMB0wxMb2Y6q3SiE+UMNgDVxc1W6N99HhRM3K95m/7DZunZj/X7+Zr5jO/N T8HmzeMDLZbtx9q/yG403RgKgqX3JdtruL/brloTOQHYijCAEo21KvjI5T1fqfqNM1zv IfPWPE6TdbzO3fiiidOXzDEwGFkOiyxYbnyLV9qXRgPeqhXTal8egtUppE46j3BNlwxg 0/K8y3ESUQihagJusSJ2tWJeu7VEkqNnJStFR6zVfGlZw9ttc95lJBK5/K2ueN46Tn6T uX375nj+F0PenkQr9Jyu3LRVAnYtTPtyVjClOHZWmGSVng6CqENui1UwcWd2470dGVt8 CQKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=/j6yv6+Ku7KXNVVOYpvwLhxyPAj/+OpFFq2HsmTelKU=; b=s+xL+XefBuKrc5BWRQ+beS65YbF1inZeXuDVQk/EuvcKruqE3rIJq+2wHj3wzlK3Ar mxswekokM6sUe2dco6jwUD0HMCqZ9RJZulHyEM7pcvj1HMn0NLiflQjZr4aYdwMLGMnP gPvUYlXUrRoYLBeErlahEoxiHDXDZdQom31b3fIzy3fN74J9FCC8IWpVHXalHEqCQuZ4 rsjJm6Xoz64jbR/2Hy0ooAOxsxHHjwdRrVDoQScb7RLTO69PrPqpr4YEqaYB+/mvjrQC 8TSBcGh7mkUwXZ0+76/Drzt5AuqnhmbkOF7GYjTJutzTOC2/o2rH4r0LwwUNM+5qTjzw lQiA== X-Gm-Message-State: AOAM531SDo/QOcgpEm8Jf3k5RuGkBExbcb3uzo0Cq9B+vrZynFnlTUMt FmjfwHigT+3VDwEIDG5oIMYylV62n1cRgA== X-Google-Smtp-Source: ABdhPJylwM+QqkMC3yBbQTg9bJ7ZkETdzwvGbCdH9xVy46m+hhV1uOAp2KU2ao/EHeoNE7bMbsLdAQWv9NMZug== X-Received: from abdulras.c.googlers.com ([fda3:e722:ac3:cc00:24:72f4:c0a8:41e1]) (user=abdulras job=sendgmr) by 2002:a25:c589:: with SMTP id v131mr621116ybe.344.1628098345153; Wed, 04 Aug 2021 10:32:25 -0700 (PDT) Date: Wed, 4 Aug 2021 17:32:14 +0000 Message-Id: <20210804173214.1027994-1-abdulras@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.32.0.554.ge1b32706d8-goog Subject: [PATCH v3] riscv: explicitly use symbol offsets for VDSO From: Saleem Abdulrasool To: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Palmer Dabbelt , Nathan Chancellor , Nick Desaulniers , Bill Wendling , clang-built-linux@googlegroups.com, Saleem Abdulrasool Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The current implementation of the `__rt_sigaction` reference computed an absolute offset relative to the mapped base of the VDSO. While this can be handled in the medlow model, the medany model cannot handle this as it is meant to be position independent. The current implementation relied on the BFD linker relaxing the PC-relative relocation into an absolute relocation as it was a near-zero address allowing it to be referenced relative to `zero`. We now extract the offsets and create a generated header allowing the build with LLVM and lld to succeed as we no longer depend on the linker rewriting address references near zero. This change was largely modelled after the ARM64 target which does something similar. Signed-off-by: Saleem Abdulrasool --- arch/riscv/Makefile | 4 ++++ arch/riscv/include/asm/vdso.h | 14 ++---------- arch/riscv/kernel/vdso/Makefile | 25 ++++++++++------------ arch/riscv/kernel/vdso/gen_vdso_offsets.sh | 5 +++++ arch/riscv/kernel/vdso/so2s.sh | 6 ------ 5 files changed, 22 insertions(+), 32 deletions(-) create mode 100755 arch/riscv/kernel/vdso/gen_vdso_offsets.sh delete mode 100755 arch/riscv/kernel/vdso/so2s.sh diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index bc74afdbf31e..e026b2d0a5a4 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -108,6 +108,10 @@ PHONY += vdso_install vdso_install: $(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso $@ +prepare: vdso_prepare +vdso_prepare: prepare0 + $(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso include/generated/vdso-offsets.h + ifneq ($(CONFIG_XIP_KERNEL),y) ifeq ($(CONFIG_RISCV_M_MODE)$(CONFIG_SOC_CANAAN),yy) KBUILD_IMAGE := $(boot)/loader.bin diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h index 1453a2f563bc..d8d003c2b5a3 100644 --- a/arch/riscv/include/asm/vdso.h +++ b/arch/riscv/include/asm/vdso.h @@ -9,25 +9,15 @@ #define _ASM_RISCV_VDSO_H #include +#include #ifndef CONFIG_GENERIC_TIME_VSYSCALL struct vdso_data { }; #endif -/* - * The VDSO symbols are mapped into Linux so we can just use regular symbol - * addressing to get their offsets in userspace. The symbols are mapped at an - * offset of 0, but since the linker must support setting weak undefined - * symbols to the absolute address 0 it also happens to support other low - * addresses even when the code model suggests those low addresses would not - * otherwise be availiable. - */ #define VDSO_SYMBOL(base, name) \ -({ \ - extern const char __vdso_##name[]; \ - (void __user *)((unsigned long)(base) + __vdso_##name); \ -}) + (void __user *)((unsigned long)(base) + __vdso_##name##_offset) asmlinkage long sys_riscv_flush_icache(uintptr_t, uintptr_t, uintptr_t); diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile index 24d936c147cd..f8cb9144a284 100644 --- a/arch/riscv/kernel/vdso/Makefile +++ b/arch/riscv/kernel/vdso/Makefile @@ -23,10 +23,10 @@ ifneq ($(c-gettimeofday-y),) endif # Build rules -targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.lds vdso-syms.S +targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.lds obj-vdso := $(addprefix $(obj)/, $(obj-vdso)) -obj-y += vdso.o vdso-syms.o +obj-y += vdso.o CPPFLAGS_vdso.lds += -P -C -U$(ARCH) # Disable -pg to prevent insert call site @@ -43,20 +43,22 @@ $(obj)/vdso.o: $(obj)/vdso.so # link rule for the .so file, .lds has to be first $(obj)/vdso.so.dbg: $(obj)/vdso.lds $(obj-vdso) FORCE $(call if_changed,vdsold) -LDFLAGS_vdso.so.dbg = -shared -s -soname=linux-vdso.so.1 \ +LDFLAGS_vdso.so.dbg = -shared -S -soname=linux-vdso.so.1 \ --build-id=sha1 --hash-style=both --eh-frame-hdr -# We also create a special relocatable object that should mirror the symbol -# table and layout of the linked DSO. With ld --just-symbols we can then -# refer to these symbols in the kernel code rather than hand-coded addresses. -$(obj)/vdso-syms.S: $(obj)/vdso.so FORCE - $(call if_changed,so2s) - # strip rule for the .so file $(obj)/%.so: OBJCOPYFLAGS := -S $(obj)/%.so: $(obj)/%.so.dbg FORCE $(call if_changed,objcopy) +# Generate VDSO offsets using helper script +gen-vdsosym := $(srctree)/$(src)/gen_vdso_offsets.sh +quiet_cmd_vdsosym = VDSOSYM $@ + cmd_vdsosym = $(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@ + +include/generated/vdso-offsets.h: $(obj)/vdso.so.dbg FORCE + $(call if_changed,vdsosym) + # actual build commands # The DSO images are built using a special linker script # Make sure only to export the intended __vdso_xxx symbol offsets. @@ -65,11 +67,6 @@ quiet_cmd_vdsold = VDSOLD $@ $(OBJCOPY) $(patsubst %, -G __vdso_%, $(vdso-syms)) $@.tmp $@ && \ rm $@.tmp -# Extracts symbol offsets from the VDSO, converting them into an assembly file -# that contains the same symbols at the same offsets. -quiet_cmd_so2s = SO2S $@ - cmd_so2s = $(NM) -D $< | $(srctree)/$(src)/so2s.sh > $@ - # install commands for the unstripped file quiet_cmd_vdso_install = INSTALL $@ cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@ diff --git a/arch/riscv/kernel/vdso/gen_vdso_offsets.sh b/arch/riscv/kernel/vdso/gen_vdso_offsets.sh new file mode 100755 index 000000000000..c2e5613f3495 --- /dev/null +++ b/arch/riscv/kernel/vdso/gen_vdso_offsets.sh @@ -0,0 +1,5 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 + +LC_ALL=C +sed -n -e 's/^[0]\+\(0[0-9a-fA-F]*\) . \(__vdso_[a-zA-Z0-9_]*\)$/\#define \2_offset\t0x\1/p' diff --git a/arch/riscv/kernel/vdso/so2s.sh b/arch/riscv/kernel/vdso/so2s.sh deleted file mode 100755 index e64cb6d9440e..000000000000 --- a/arch/riscv/kernel/vdso/so2s.sh +++ /dev/null @@ -1,6 +0,0 @@ -#!/bin/sh -# SPDX-License-Identifier: GPL-2.0+ -# Copyright 2020 Palmer Dabbelt - -sed 's!\([0-9a-f]*\) T \([a-z0-9_]*\)\(@@LINUX_4.15\)*!.global \2\n.set \2,0x\1!' \ -| grep '^\.' -- 2.32.0.554.ge1b32706d8-goog