diff options
Diffstat (limited to 'arch/arm64/kernel/vdso')
| -rw-r--r-- | arch/arm64/kernel/vdso/.gitignore | 2 | ||||
| -rw-r--r-- | arch/arm64/kernel/vdso/Makefile | 90 | ||||
| -rwxr-xr-x | arch/arm64/kernel/vdso/gen_vdso_offsets.sh | 16 | ||||
| -rw-r--r-- | arch/arm64/kernel/vdso/note.S | 23 | ||||
| -rw-r--r-- | arch/arm64/kernel/vdso/sigreturn.S | 80 | ||||
| -rw-r--r-- | arch/arm64/kernel/vdso/vdso.lds.S | 112 | ||||
| -rw-r--r-- | arch/arm64/kernel/vdso/vgettimeofday.c | 29 |
7 files changed, 352 insertions, 0 deletions
diff --git a/arch/arm64/kernel/vdso/.gitignore b/arch/arm64/kernel/vdso/.gitignore new file mode 100644 index 0000000000..652e31d825 --- /dev/null +++ b/arch/arm64/kernel/vdso/.gitignore @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +vdso.lds diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile new file mode 100644 index 0000000000..fe7a53c678 --- /dev/null +++ b/arch/arm64/kernel/vdso/Makefile @@ -0,0 +1,90 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Building a vDSO image for AArch64. +# +# Author: Will Deacon <will.deacon@arm.com> +# Heavily based on the vDSO Makefiles for other archs. +# + +# Include the generic Makefile to check the built vdso. +include $(srctree)/lib/vdso/Makefile + +obj-vdso := vgettimeofday.o note.o sigreturn.o + +# Build rules +targets := $(obj-vdso) vdso.so vdso.so.dbg +obj-vdso := $(addprefix $(obj)/, $(obj-vdso)) + +btildflags-$(CONFIG_ARM64_BTI_KERNEL) += -z force-bti + +# -Bsymbolic has been added for consistency with arm, the compat vDSO and +# potential future proofing if we end up with internal calls to the exported +# routines, as x86 does (see 6f121e548f83 ("x86, vdso: Reimplement vdso.so +# preparation in build-time C")). +ldflags-y := -shared -soname=linux-vdso.so.1 --hash-style=sysv \ + -Bsymbolic --build-id=sha1 -n $(btildflags-y) + +ifdef CONFIG_LD_ORPHAN_WARN + ldflags-y += --orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL) +endif + +ldflags-y += -T + +ccflags-y := -fno-common -fno-builtin -fno-stack-protector -ffixed-x18 +ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO + +# -Wmissing-prototypes and -Wmissing-declarations are removed from +# the CFLAGS of vgettimeofday.c to make possible to build the +# kernel with CONFIG_WERROR enabled. +CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) \ + $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) \ + $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) \ + -Wmissing-prototypes -Wmissing-declarations +KASAN_SANITIZE := n +KCSAN_SANITIZE := n +UBSAN_SANITIZE := n +OBJECT_FILES_NON_STANDARD := y +KCOV_INSTRUMENT := n + +CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny -fasynchronous-unwind-tables + +ifneq ($(c-gettimeofday-y),) + CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y) +endif + +# Disable gcov profiling for VDSO code +GCOV_PROFILE := n + +targets += vdso.lds +CPPFLAGS_vdso.lds += -P -C -U$(ARCH) + +# Link rule for the .so file, .lds has to be first +$(obj)/vdso.so.dbg: $(obj)/vdso.lds $(obj-vdso) FORCE + $(call if_changed,vdsold_and_vdso_check) + +# Strip rule for the .so file +$(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 +quiet_cmd_vdsold_and_vdso_check = LD $@ + cmd_vdsold_and_vdso_check = $(cmd_ld); $(cmd_vdso_check) + +# Install commands for the unstripped file +quiet_cmd_vdso_install = INSTALL $@ + cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@ + +vdso.so: $(obj)/vdso.so.dbg + @mkdir -p $(MODLIB)/vdso + $(call cmd,vdso_install) + +vdso_install: vdso.so diff --git a/arch/arm64/kernel/vdso/gen_vdso_offsets.sh b/arch/arm64/kernel/vdso/gen_vdso_offsets.sh new file mode 100755 index 0000000000..0387209d65 --- /dev/null +++ b/arch/arm64/kernel/vdso/gen_vdso_offsets.sh @@ -0,0 +1,16 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 + +# +# Match symbols in the DSO that look like VDSO_*; produce a header file +# of constant offsets into the shared object. +# +# Doing this inside the Makefile will break the $(filter-out) function, +# causing Kbuild to rebuild the vdso-offsets header file every time. +# +# Author: Will Deacon <will.deacon@arm.com> +# + +LC_ALL=C +sed -n -e 's/^00*/0/' -e \ +'s/^\([0-9a-fA-F]*\) . VDSO_\([a-zA-Z0-9_]*\)$/\#define vdso_offset_\2 0x\1/p' diff --git a/arch/arm64/kernel/vdso/note.S b/arch/arm64/kernel/vdso/note.S new file mode 100644 index 0000000000..3d4e82290c --- /dev/null +++ b/arch/arm64/kernel/vdso/note.S @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2012 ARM Limited + * + * Author: Will Deacon <will.deacon@arm.com> + * + * This supplies .note.* sections to go into the PT_NOTE inside the vDSO text. + * Here we can supply some information useful to userland. + */ + +#include <linux/uts.h> +#include <linux/version.h> +#include <linux/elfnote.h> +#include <linux/build-salt.h> +#include <asm/assembler.h> + +ELFNOTE_START(Linux, 0, "a") + .long LINUX_VERSION_CODE +ELFNOTE_END + +BUILD_SALT + +emit_aarch64_feature_1_and diff --git a/arch/arm64/kernel/vdso/sigreturn.S b/arch/arm64/kernel/vdso/sigreturn.S new file mode 100644 index 0000000000..0e18729abc --- /dev/null +++ b/arch/arm64/kernel/vdso/sigreturn.S @@ -0,0 +1,80 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Sigreturn trampoline for returning from a signal when the SA_RESTORER + * flag is not set. It serves primarily as a hall of shame for crappy + * unwinders and features an exciting but mysterious NOP instruction. + * + * It's also fragile as hell, so please think twice before changing anything + * in here. + * + * Copyright (C) 2012 ARM Limited + * + * Author: Will Deacon <will.deacon@arm.com> + */ + +#include <linux/linkage.h> +#include <asm/assembler.h> +#include <asm/unistd.h> + + .text + +/* + * NOTE!!! You may notice that all of the .cfi directives in this file have + * been commented out. This is because they have been shown to trigger segfaults + * in libgcc when unwinding out of a SIGCANCEL handler to invoke pthread + * cleanup handlers during the thread cancellation dance. By omitting the + * directives, we trigger an arm64-specific fallback path in the unwinder which + * recognises the signal frame and restores many of the registers directly from + * the sigcontext. Re-enabling the cfi directives here therefore needs to be + * much more comprehensive to reduce the risk of further regressions. + */ + +/* Ensure that the mysterious NOP can be associated with a function. */ +// .cfi_startproc + +/* + * .cfi_signal_frame causes the corresponding Frame Description Entry (FDE) in + * the .eh_frame section to be annotated as a signal frame. This allows DWARF + * unwinders (e.g. libstdc++) to implement _Unwind_GetIPInfo() and identify + * the next frame using the unmodified return address instead of subtracting 1, + * which may yield the wrong FDE. + */ +// .cfi_signal_frame + +/* + * Tell the unwinder where to locate the frame record linking back to the + * interrupted context. We don't provide unwind info for registers other than + * the frame pointer and the link register here; in practice, this is likely to + * be insufficient for unwinding in C/C++ based runtimes, especially without a + * means to restore the stack pointer. Thankfully, unwinders and debuggers + * already have baked-in strategies for attempting to unwind out of signals. + */ +// .cfi_def_cfa x29, 0 +// .cfi_offset x29, 0 * 8 +// .cfi_offset x30, 1 * 8 + +/* + * This mysterious NOP is required for some unwinders (e.g. libc++) that + * unconditionally subtract one from the result of _Unwind_GetIP() in order to + * identify the calling function. + * Hack borrowed from arch/powerpc/kernel/vdso64/sigtramp.S. + */ + nop // Mysterious NOP + +/* + * GDB, libgcc and libunwind rely on being able to identify the sigreturn + * instruction sequence to unwind from signal handlers. We cannot, therefore, + * use SYM_FUNC_START() here, as it will emit a BTI C instruction and break the + * unwinder. Thankfully, this function is only ever called from a RET and so + * omitting the landing pad is perfectly fine. + */ +SYM_CODE_START(__kernel_rt_sigreturn) +// PLEASE DO NOT MODIFY + mov x8, #__NR_rt_sigreturn +// PLEASE DO NOT MODIFY + svc #0 +// PLEASE DO NOT MODIFY +// .cfi_endproc +SYM_CODE_END(__kernel_rt_sigreturn) + +emit_aarch64_feature_1_and diff --git a/arch/arm64/kernel/vdso/vdso.lds.S b/arch/arm64/kernel/vdso/vdso.lds.S new file mode 100644 index 0000000000..45354f2ddf --- /dev/null +++ b/arch/arm64/kernel/vdso/vdso.lds.S @@ -0,0 +1,112 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * GNU linker script for the VDSO library. +* + * Copyright (C) 2012 ARM Limited + * + * Author: Will Deacon <will.deacon@arm.com> + * Heavily based on the vDSO linker scripts for other archs. + */ + +#include <linux/const.h> +#include <asm/page.h> +#include <asm/vdso.h> +#include <asm-generic/vmlinux.lds.h> + +OUTPUT_FORMAT("elf64-littleaarch64", "elf64-bigaarch64", "elf64-littleaarch64") +OUTPUT_ARCH(aarch64) + +SECTIONS +{ + PROVIDE(_vdso_data = . - __VVAR_PAGES * PAGE_SIZE); +#ifdef CONFIG_TIME_NS + PROVIDE(_timens_data = _vdso_data + PAGE_SIZE); +#endif + . = VDSO_LBASE + SIZEOF_HEADERS; + + .hash : { *(.hash) } :text + .gnu.hash : { *(.gnu.hash) } + .dynsym : { *(.dynsym) } + .dynstr : { *(.dynstr) } + .gnu.version : { *(.gnu.version) } + .gnu.version_d : { *(.gnu.version_d) } + .gnu.version_r : { *(.gnu.version_r) } + + /* + * Discard .note.gnu.property sections which are unused and have + * different alignment requirement from vDSO note sections. + */ + /DISCARD/ : { + *(.note.GNU-stack .note.gnu.property) + } + .note : { *(.note.*) } :text :note + + . = ALIGN(16); + + .text : { *(.text*) } :text =0xd503201f + PROVIDE (__etext = .); + PROVIDE (_etext = .); + PROVIDE (etext = .); + + . = ALIGN(4); + .altinstructions : { + *(.altinstructions) + } + + .dynamic : { *(.dynamic) } :text :dynamic + + .rela.dyn : ALIGN(8) { *(.rela .rela*) } + + .rodata : { + *(.rodata*) + *(.got) + *(.got.plt) + *(.plt) + *(.plt.*) + *(.iplt) + *(.igot .igot.plt) + } :text + + _end = .; + PROVIDE(end = .); + + DWARF_DEBUG + ELF_DETAILS + + /DISCARD/ : { + *(.data .data.* .gnu.linkonce.d.* .sdata*) + *(.bss .sbss .dynbss .dynsbss) + *(.eh_frame .eh_frame_hdr) + } +} + +/* + * We must supply the ELF program headers explicitly to get just one + * PT_LOAD segment, and set the flags explicitly to make segments read-only. + */ +PHDRS +{ + text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */ + dynamic PT_DYNAMIC FLAGS(4); /* PF_R */ + note PT_NOTE FLAGS(4); /* PF_R */ +} + +/* + * This controls what symbols we export from the DSO. + */ +VERSION +{ + LINUX_2.6.39 { + global: + __kernel_rt_sigreturn; + __kernel_gettimeofday; + __kernel_clock_gettime; + __kernel_clock_getres; + local: *; + }; +} + +/* + * Make the sigreturn code visible to the kernel. + */ +VDSO_sigtramp = __kernel_rt_sigreturn; diff --git a/arch/arm64/kernel/vdso/vgettimeofday.c b/arch/arm64/kernel/vdso/vgettimeofday.c new file mode 100644 index 0000000000..9941c5b04f --- /dev/null +++ b/arch/arm64/kernel/vdso/vgettimeofday.c @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * ARM64 userspace implementations of gettimeofday() and similar. + * + * Copyright (C) 2018 ARM Limited + * + */ + +int __kernel_clock_gettime(clockid_t clock, struct __kernel_timespec *ts); +int __kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz); +int __kernel_clock_getres(clockid_t clock_id, struct __kernel_timespec *res); + +int __kernel_clock_gettime(clockid_t clock, + struct __kernel_timespec *ts) +{ + return __cvdso_clock_gettime(clock, ts); +} + +int __kernel_gettimeofday(struct __kernel_old_timeval *tv, + struct timezone *tz) +{ + return __cvdso_gettimeofday(tv, tz); +} + +int __kernel_clock_getres(clockid_t clock_id, + struct __kernel_timespec *res) +{ + return __cvdso_clock_getres(clock_id, res); +} |