From: Josh Poimboeuf <jpoim...@kernel.org> In preparation for unwinding user space stacks with sframe, add basic sframe compile infrastructure and support for reading the .sframe section header.
sframe_add_section() reads the header and unconditionally returns an error, so it's not very useful yet. A subsequent patch will improve that. Link: https://lore.kernel.org/all/f27e8463783febfa0dabb0432a3dd6be8ad98412.1737511963.git.jpoim...@kernel.org/ Signed-off-by: Josh Poimboeuf <jpoim...@kernel.org> Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org> --- MAINTAINERS | 1 + arch/Kconfig | 3 + include/linux/sframe.h | 40 ++++++++++++ kernel/unwind/Makefile | 3 +- kernel/unwind/sframe.c | 136 +++++++++++++++++++++++++++++++++++++++++ kernel/unwind/sframe.h | 71 +++++++++++++++++++++ 6 files changed, 253 insertions(+), 1 deletion(-) create mode 100644 include/linux/sframe.h create mode 100644 kernel/unwind/sframe.c create mode 100644 kernel/unwind/sframe.h diff --git a/MAINTAINERS b/MAINTAINERS index 370d780fd5f8..a6a94d2d03b0 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -25932,6 +25932,7 @@ USERSPACE STACK UNWINDING M: Josh Poimboeuf <jpoim...@kernel.org> M: Steven Rostedt <rost...@goodmis.org> S: Maintained +F: include/linux/sframe.h F: include/linux/unwind*.h F: kernel/unwind/ diff --git a/arch/Kconfig b/arch/Kconfig index 2c41d3072910..c54d35e2f860 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -446,6 +446,9 @@ config HAVE_UNWIND_USER_COMPAT_FP bool depends on HAVE_UNWIND_USER_FP +config HAVE_UNWIND_USER_SFRAME + bool + config HAVE_PERF_REGS bool help diff --git a/include/linux/sframe.h b/include/linux/sframe.h new file mode 100644 index 000000000000..0584f661f698 --- /dev/null +++ b/include/linux/sframe.h @@ -0,0 +1,40 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_SFRAME_H +#define _LINUX_SFRAME_H + +#include <linux/mm_types.h> +#include <linux/unwind_user_types.h> + +#ifdef CONFIG_HAVE_UNWIND_USER_SFRAME + +struct sframe_section { + unsigned long sframe_start; + unsigned long sframe_end; + unsigned long text_start; + unsigned long text_end; + + unsigned long fdes_start; + unsigned long fres_start; + unsigned long fres_end; + unsigned int num_fdes; + + signed char ra_off; + signed char fp_off; +}; + +extern int sframe_add_section(unsigned long sframe_start, unsigned long sframe_end, + unsigned long text_start, unsigned long text_end); +extern int sframe_remove_section(unsigned long sframe_addr); + +#else /* !CONFIG_HAVE_UNWIND_USER_SFRAME */ + +static inline int sframe_add_section(unsigned long sframe_start, unsigned long sframe_end, + unsigned long text_start, unsigned long text_end) +{ + return -ENOSYS; +} +static inline int sframe_remove_section(unsigned long sframe_addr) { return -ENOSYS; } + +#endif /* CONFIG_HAVE_UNWIND_USER_SFRAME */ + +#endif /* _LINUX_SFRAME_H */ diff --git a/kernel/unwind/Makefile b/kernel/unwind/Makefile index eae37bea54fd..146038165865 100644 --- a/kernel/unwind/Makefile +++ b/kernel/unwind/Makefile @@ -1 +1,2 @@ - obj-$(CONFIG_UNWIND_USER) += user.o deferred.o + obj-$(CONFIG_UNWIND_USER) += user.o deferred.o + obj-$(CONFIG_HAVE_UNWIND_USER_SFRAME) += sframe.o diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c new file mode 100644 index 000000000000..20287f795b36 --- /dev/null +++ b/kernel/unwind/sframe.c @@ -0,0 +1,136 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Userspace sframe access functions + */ + +#define pr_fmt(fmt) "sframe: " fmt + +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/srcu.h> +#include <linux/uaccess.h> +#include <linux/mm.h> +#include <linux/string_helpers.h> +#include <linux/sframe.h> +#include <linux/unwind_user_types.h> + +#include "sframe.h" + +#define dbg(fmt, ...) \ + pr_debug("%s (%d): " fmt, current->comm, current->pid, ##__VA_ARGS__) + +static void free_section(struct sframe_section *sec) +{ + kfree(sec); +} + +static int sframe_read_header(struct sframe_section *sec) +{ + unsigned long header_end, fdes_start, fdes_end, fres_start, fres_end; + struct sframe_header shdr; + unsigned int num_fdes; + + if (copy_from_user(&shdr, (void __user *)sec->sframe_start, sizeof(shdr))) { + dbg("header usercopy failed\n"); + return -EFAULT; + } + + if (shdr.preamble.magic != SFRAME_MAGIC || + shdr.preamble.version != SFRAME_VERSION_2 || + !(shdr.preamble.flags & SFRAME_F_FDE_SORTED) || + shdr.auxhdr_len) { + dbg("bad/unsupported sframe header\n"); + return -EINVAL; + } + + if (!shdr.num_fdes || !shdr.num_fres) { + dbg("no fde/fre entries\n"); + return -EINVAL; + } + + header_end = sec->sframe_start + SFRAME_HEADER_SIZE(shdr); + if (header_end >= sec->sframe_end) { + dbg("header doesn't fit in section\n"); + return -EINVAL; + } + + num_fdes = shdr.num_fdes; + fdes_start = header_end + shdr.fdes_off; + fdes_end = fdes_start + (num_fdes * sizeof(struct sframe_fde)); + + fres_start = header_end + shdr.fres_off; + fres_end = fres_start + shdr.fre_len; + + if (fres_start < fdes_end || fres_end > sec->sframe_end) { + dbg("inconsistent fde/fre offsets\n"); + return -EINVAL; + } + + sec->num_fdes = num_fdes; + sec->fdes_start = fdes_start; + sec->fres_start = fres_start; + sec->fres_end = fres_end; + + sec->ra_off = shdr.cfa_fixed_ra_offset; + sec->fp_off = shdr.cfa_fixed_fp_offset; + + return 0; +} + +int sframe_add_section(unsigned long sframe_start, unsigned long sframe_end, + unsigned long text_start, unsigned long text_end) +{ + struct maple_tree *sframe_mt = ¤t->mm->sframe_mt; + struct vm_area_struct *sframe_vma, *text_vma; + struct mm_struct *mm = current->mm; + struct sframe_section *sec; + int ret; + + if (!sframe_start || !sframe_end || !text_start || !text_end) { + dbg("zero-length sframe/text address\n"); + return -EINVAL; + } + + scoped_guard(mmap_read_lock, mm) { + sframe_vma = vma_lookup(mm, sframe_start); + if (!sframe_vma || sframe_end > sframe_vma->vm_end) { + dbg("bad sframe address (0x%lx - 0x%lx)\n", + sframe_start, sframe_end); + return -EINVAL; + } + + text_vma = vma_lookup(mm, text_start); + if (!text_vma || + !(text_vma->vm_flags & VM_EXEC) || + text_end > text_vma->vm_end) { + dbg("bad text address (0x%lx - 0x%lx)\n", + text_start, text_end); + return -EINVAL; + } + } + + sec = kzalloc(sizeof(*sec), GFP_KERNEL); + if (!sec) + return -ENOMEM; + + sec->sframe_start = sframe_start; + sec->sframe_end = sframe_end; + sec->text_start = text_start; + sec->text_end = text_end; + + ret = sframe_read_header(sec); + if (ret) + goto err_free; + + /* TODO nowhere to store it yet - just free it and return an error */ + ret = -ENOSYS; + +err_free: + free_section(sec); + return ret; +} + +int sframe_remove_section(unsigned long sframe_start) +{ + return -ENOSYS; +} diff --git a/kernel/unwind/sframe.h b/kernel/unwind/sframe.h new file mode 100644 index 000000000000..e9bfccfaf5b4 --- /dev/null +++ b/kernel/unwind/sframe.h @@ -0,0 +1,71 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * From https://www.sourceware.org/binutils/docs/sframe-spec.html + */ +#ifndef _SFRAME_H +#define _SFRAME_H + +#include <linux/types.h> + +#define SFRAME_VERSION_1 1 +#define SFRAME_VERSION_2 2 +#define SFRAME_MAGIC 0xdee2 + +#define SFRAME_F_FDE_SORTED 0x1 +#define SFRAME_F_FRAME_POINTER 0x2 + +#define SFRAME_ABI_AARCH64_ENDIAN_BIG 1 +#define SFRAME_ABI_AARCH64_ENDIAN_LITTLE 2 +#define SFRAME_ABI_AMD64_ENDIAN_LITTLE 3 + +#define SFRAME_FDE_TYPE_PCINC 0 +#define SFRAME_FDE_TYPE_PCMASK 1 + +struct sframe_preamble { + u16 magic; + u8 version; + u8 flags; +} __packed; + +struct sframe_header { + struct sframe_preamble preamble; + u8 abi_arch; + s8 cfa_fixed_fp_offset; + s8 cfa_fixed_ra_offset; + u8 auxhdr_len; + u32 num_fdes; + u32 num_fres; + u32 fre_len; + u32 fdes_off; + u32 fres_off; +} __packed; + +#define SFRAME_HEADER_SIZE(header) \ + ((sizeof(struct sframe_header) + header.auxhdr_len)) + +#define SFRAME_AARCH64_PAUTH_KEY_A 0 +#define SFRAME_AARCH64_PAUTH_KEY_B 1 + +struct sframe_fde { + s32 start_addr; + u32 func_size; + u32 fres_off; + u32 fres_num; + u8 info; + u8 rep_size; + u16 padding; +} __packed; + +#define SFRAME_FUNC_FRE_TYPE(data) (data & 0xf) +#define SFRAME_FUNC_FDE_TYPE(data) ((data >> 4) & 0x1) +#define SFRAME_FUNC_PAUTH_KEY(data) ((data >> 5) & 0x1) + +#define SFRAME_BASE_REG_FP 0 +#define SFRAME_BASE_REG_SP 1 + +#define SFRAME_FRE_CFA_BASE_REG_ID(data) (data & 0x1) +#define SFRAME_FRE_OFFSET_COUNT(data) ((data >> 1) & 0xf) +#define SFRAME_FRE_OFFSET_SIZE(data) ((data >> 5) & 0x3) +#define SFRAME_FRE_MANGLED_RA_P(data) ((data >> 7) & 0x1) + +#endif /* _SFRAME_H */ -- 2.47.2
