From patchwork Mon Feb 8 18:53:10 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Jones X-Patchwork-Id: 580468 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id AD451140C72 for ; Tue, 9 Feb 2016 05:53:53 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754539AbcBHSxp (ORCPT ); Mon, 8 Feb 2016 13:53:45 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52395 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754455AbcBHSxo (ORCPT ); Mon, 8 Feb 2016 13:53:44 -0500 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (Postfix) with ESMTPS id 2F31D1B282C; Mon, 8 Feb 2016 18:53:44 +0000 (UTC) Received: from hawk.localdomain.com (dhcp-1-158.brq.redhat.com [10.34.1.158]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u18IrHb0006285; Mon, 8 Feb 2016 13:53:42 -0500 From: Andrew Jones To: kvm@vger.kernel.org, kvm-ppc@vger.kernel.org Cc: thuth@redhat.com, dgibson@redhat.com, david@gibson.dropbear.id.au, agraf@suse.de, lvivier@redhat.com, pbonzini@redhat.com Subject: [kvm-unit-tests PATCH v2 10/14] powerpc/ppc64: relocate linker VMAs Date: Mon, 8 Feb 2016 19:53:10 +0100 Message-Id: <1454957594-30601-11-git-send-email-drjones@redhat.com> In-Reply-To: <1454957594-30601-1-git-send-email-drjones@redhat.com> References: <1454957594-30601-1-git-send-email-drjones@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org QEMU loads the unit test, but due to the way it translates the unit test's linker VMA to the LMA, we can't just link such that VMA == LMA. Thus, we link with VMA == 0x0, and then deal with relocation. Signed-off-by: Andrew Jones --- configure | 2 ++ powerpc/Makefile.common | 11 ++++++++-- powerpc/Makefile.ppc64 | 1 + powerpc/cstart64.S | 40 +++++++++++++++++++++++++++++++---- powerpc/flat.lds | 13 +++++++++++- powerpc/reloc64.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 115 insertions(+), 7 deletions(-) create mode 100644 powerpc/reloc64.c diff --git a/configure b/configure index b367224093369..b2ad199da7873 100755 --- a/configure +++ b/configure @@ -5,6 +5,7 @@ kerneldir=/lib/modules/$(uname -r)/build cc=gcc ld=ld objcopy=objcopy +objdump=objdump ar=ar arch=`uname -m | sed -e s/i.86/i386/ | sed -e 's/arm.*/arm/'` host=$arch @@ -132,6 +133,7 @@ PROCESSOR=$processor CC=$cross_prefix$cc LD=$cross_prefix$ld OBJCOPY=$cross_prefix$objcopy +OBJDUMP=$cross_prefix$objdump AR=$cross_prefix$ar API=$api TEST_DIR=$testdir diff --git a/powerpc/Makefile.common b/powerpc/Makefile.common index 89ad7a1907ac9..074f5672356b1 100644 --- a/powerpc/Makefile.common +++ b/powerpc/Makefile.common @@ -22,6 +22,7 @@ CFLAGS += -Wextra CFLAGS += -O2 CFLAGS += -I lib -I lib/libfdt CFLAGS += -Wa,-mregnames +CFLAGS += -fpie asm-offsets = lib/$(ARCH)/asm-offsets.h include scripts/asm-offsets.mak @@ -38,11 +39,17 @@ libgcc := $(shell $(CC) $(machine) --print-libgcc-file-name) start_addr := $(shell printf "%x\n" $$(( $(phys_base) + $(kernel_offset) ))) FLATLIBS = $(libcflat) $(LIBFDT_archive) $(libgcc) -%.elf: LDFLAGS = $(CFLAGS) -nostdlib +%.elf: LDFLAGS = $(CFLAGS) -nostdlib -pie %.elf: %.o $(FLATLIBS) powerpc/flat.lds $(CC) $(LDFLAGS) -o $@ \ -Wl,-T,powerpc/flat.lds,--build-id=none,-Ttext=$(start_addr) \ $(filter %.o, $^) $(FLATLIBS) + @echo -n Checking $@ for unsupported reloc types... + @if $(OBJDUMP) -R $@ | grep R_ | grep -v R_PPC64_RELATIVE; then \ + false; \ + else \ + echo " looks good."; \ + fi powerpc_clean: libfdt_clean asm_offsets_clean $(RM) $(TEST_DIR)/*.{o,elf} \ @@ -54,4 +61,4 @@ generated_files = $(asm-offsets) test_cases: $(generated_files) $(tests-common) $(tests) -$(TEST_DIR)/selftest.elf: $(cstart.o) $(TEST_DIR)/selftest.o +$(TEST_DIR)/selftest.elf: $(cstart.o) $(reloc.o) $(TEST_DIR)/selftest.o diff --git a/powerpc/Makefile.ppc64 b/powerpc/Makefile.ppc64 index e9aa9f560204a..a1e2696c8d4f0 100644 --- a/powerpc/Makefile.ppc64 +++ b/powerpc/Makefile.ppc64 @@ -8,6 +8,7 @@ ldarch = elf64-powerpc kernel_offset = 0x0 cstart.o = $(TEST_DIR)/cstart64.o +reloc.o = $(TEST_DIR)/reloc64.o cflatobjs += lib/ppc64/processor.o cflatobjs += lib/ppc64/spinlock.o diff --git a/powerpc/cstart64.S b/powerpc/cstart64.S index ce942f93bef05..97376fb025760 100644 --- a/powerpc/cstart64.S +++ b/powerpc/cstart64.S @@ -25,18 +25,50 @@ */ .globl start start: - LOAD_REG_IMMEDIATE(r1, stackptr) - LOAD_REG_IMMEDIATE(r2, tocptr) + /* + * We were loaded at QEMU's kernel load address, but we're not + * allowed to link there due to how QEMU deals with linker VMAs, + * so we just linked at zero. This means the first thing to do is + * to find our stack and toc, and then do a relocate. + */ + bl 0f +0: mflr r31 + subi r31, r31, 0b - start /* QEMU's kernel load address */ + ld r1, (p_stack - start)(r31) + ld r2, (p_toc - start)(r31) + add r1, r1, r31 + add r2, r2, r31 + + /* save DTB pointer */ + std r3, 56(r1) + + /* + * Call relocate. relocate is C code, but careful to not use + * any global references, as they may use absolute addresses, + * which are, obviously, not yet relocated. + */ + mr r3, r31 + ld r4, (p_dyn - start)(r31) + add r4, r4, r31 + bl relocate + + /* complete setup */ + ld r3, 56(r1) bl setup /* run the test */ - LOAD_REG_IMMEDIATE(r5, __argc) - LOAD_REG_IMMEDIATE(r4, __argv) + LOAD_REG_ADDR(r5, __argc) + LOAD_REG_ADDR(r4, __argv) lwz r3, 0(r5) bl main bl exit b halt +.align 3 +p_stack: .llong stackptr +p_toc: .llong tocptr +p_dyn: .llong dynamic_start + .text .align 3 diff --git a/powerpc/flat.lds b/powerpc/flat.lds index bd075efb2c51b..8a573d27346de 100644 --- a/powerpc/flat.lds +++ b/powerpc/flat.lds @@ -6,11 +6,22 @@ SECTIONS etext = .; .opd : { *(.opd) } . = ALIGN(16); + .dynamic : { + dynamic_start = .; + *(.dynamic) + } + .dynsym : { + dynsym_start = .; + *(.dynsym) + } + .rela.dyn : { *(.rela*) } + . = ALIGN(16); .data : { *(.data) + *(.data.rel*) } . = ALIGN(16); - .rodata : { *(.rodata) } + .rodata : { *(.rodata) *(.rodata.*) } . = ALIGN(16); .bss : { *(.bss) } . = ALIGN(16); diff --git a/powerpc/reloc64.c b/powerpc/reloc64.c new file mode 100644 index 0000000000000..d919372bf9288 --- /dev/null +++ b/powerpc/reloc64.c @@ -0,0 +1,55 @@ +/* + * relocate R_PPC_RELATIVE RELA entries. Normally this is done in + * assembly code to avoid the risk of using absolute addresses before + * they're relocated. We use C, but cautiously (no global references). + * + * Copyright (C) 2016, Red Hat Inc, Andrew Jones + * + * This work is licensed under the terms of the GNU LGPL, version 2. + */ +#define DT_NULL 0 +#define DT_RELA 7 +#define DT_RELACOUNT 0x6ffffff9 +#define R_PPC_RELATIVE 22 + +struct elf64_dyn { + signed long long tag; + unsigned long long val; +}; + +#define RELA_GET_TYPE(rela_ptr) ((rela_ptr)->info & 0xffffffff) +struct elf64_rela { + unsigned long long offset; + unsigned long long info; + signed long long addend; +}; + +void relocate(unsigned long load_addr, struct elf64_dyn *dyn_table) +{ + unsigned long long rela_addr = 0, rela_count = 0, *addr; + struct elf64_dyn *d = dyn_table; + struct elf64_rela *r; + + while (d && d->tag != DT_NULL) { + if (d->tag == DT_RELA) + rela_addr = d->val; + else if (d->tag == DT_RELACOUNT) + rela_count = d->val; + if (rela_addr && rela_count) + break; + ++d; + } + + if (!rela_addr || !rela_count) + return; + + r = (void *)(rela_addr + load_addr); + + while (rela_count--) { + if (RELA_GET_TYPE(r) == R_PPC_RELATIVE) { + addr = (void *)(r->offset + load_addr); + *addr = r->addend + load_addr; + } + ++r; + } +}