From: Josh Poimboeuf <[email protected]> In preparation for unwinding kernel space stacks with sframe, add basic sframe compile infrastructure and support for reading the .sframe section header. Add init_sframe_table() to read the vmlinux .sframe header at boot.
[ Jens Remus: Add support for SFrame V3. Add support for PC-relative FDE function start offset. Cleanup includes and indentation. ] [ Dylan Hatch: Repurpose patch for arm64 vmlinux. ] Signed-off-by: Josh Poimboeuf <[email protected]> Signed-off-by: Steven Rostedt (Google) <[email protected]> Reviewed-by: Indu Bhagat <[email protected]> Co-developed-by: Jens Remus <[email protected]> Signed-off-by: Jens Remus <[email protected]> Co-developed-by: Dylan Hatch <[email protected]> Signed-off-by: Dylan Hatch <[email protected]> --- This patch is adapted from commit c7db518447c6 ("unwind_user/sframe: Add support for reading .sframe headers"), and includes the header/init portions of v6 patch "sframe: Allow kernelspace sframe sections" in this series. Changes include: - kernel/unwind/sframe* is repurposed exclusively for kernel .sframe sections, under CONFIG_UNWIND_SFRAME_LOOKUP. - Replaced copy_from_user() with direct memory pointer access when reading the SFrame header. - (sashiko) Moved header size check to take place before any header fields are checked, to ensure safe memory access. Also dropped the (header + auxiliary) size helper, since non-zero auxiliary size is not currently supported. - Dropped unused userspace section tracking functions sframe_add_section(), sframe_remove_section(), free_section() - Dropped text_start/text_end section fields, since kernel/module section boundaries can be examined directly without saving. - Squashed in changes adding vmlinux-tracking kernel_sfsec and init_sframe_table(), to read vmlinux .sframe header at boot time. --- MAINTAINERS | 1 + arch/arm64/kernel/setup.c | 2 + include/linux/sframe.h | 32 ++++++++++++++++ kernel/unwind/Makefile | 3 +- kernel/unwind/sframe.c | 80 +++++++++++++++++++++++++++++++++++++++ kernel/unwind/sframe.h | 78 ++++++++++++++++++++++++++++++++++++++ 6 files changed, 195 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 6c1c95979e437..eaa691abd7a2e 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -28519,6 +28519,7 @@ M: Josh Poimboeuf <[email protected]> M: Steven Rostedt <[email protected]> S: Maintained F: arch/*/include/asm/unwind_sframe.h +F: include/linux/sframe.h F: include/linux/unwind*.h F: kernel/unwind/ diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 29c6100f0c50b..84983df605ed5 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -32,6 +32,7 @@ #include <linux/sched/task.h> #include <linux/scs.h> #include <linux/mm.h> +#include <linux/sframe.h> #include <asm/acpi.h> #include <asm/fixmap.h> @@ -373,6 +374,7 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p) "This indicates a broken bootloader or old kernel\n", boot_args[1], boot_args[2], boot_args[3]); } + init_sframe_table(); } static inline bool cpu_can_disable(unsigned int cpu) diff --git a/include/linux/sframe.h b/include/linux/sframe.h new file mode 100644 index 0000000000000..54e5cb76cb92c --- /dev/null +++ b/include/linux/sframe.h @@ -0,0 +1,32 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_SFRAME_H +#define _LINUX_SFRAME_H + +#include <linux/init.h> + +#ifdef CONFIG_UNWIND_SFRAME_LOOKUP + +struct sframe_section { + unsigned long sframe_start; + unsigned long sframe_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 struct sframe_section kernel_sfsec __ro_after_init; + +void __init init_sframe_table(void); + +#else /* !CONFIG_UNWIND_SFRAME_LOOKUP */ + +static inline void __init init_sframe_table(void) {} + +#endif /* CONFIG_UNWIND_SFRAME_LOOKUP */ + +#endif /* _LINUX_SFRAME_H */ diff --git a/kernel/unwind/Makefile b/kernel/unwind/Makefile index eae37bea54fdb..c5f9f8124564e 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_UNWIND_SFRAME_LOOKUP) += sframe.o diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c new file mode 100644 index 0000000000000..5f49f05e6226d --- /dev/null +++ b/kernel/unwind/sframe.c @@ -0,0 +1,80 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Kernel sframe access functions + */ + +#define pr_fmt(fmt) "sframe: " fmt + +#include <linux/mm.h> +#include <linux/string_helpers.h> +#include <linux/sframe.h> +#include <asm/sections.h> + +#include "sframe.h" + +static bool sframe_init __ro_after_init; +struct sframe_section kernel_sfsec __ro_after_init; + +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; + + header_end = sec->sframe_start + sizeof(struct sframe_header); + if (header_end >= sec->sframe_end) { + pr_debug("header struct doesn't fit in section\n"); + return -EINVAL; + } + + shdr = (struct sframe_header *)sec->sframe_start; + + if (shdr->preamble.magic != SFRAME_MAGIC || + shdr->preamble.version != SFRAME_VERSION_3 || + !(shdr->preamble.flags & SFRAME_F_FDE_SORTED) || + !(shdr->preamble.flags & SFRAME_F_FDE_FUNC_START_PCREL) || + shdr->auxhdr_len) { + pr_debug("bad/unsupported sframe header\n"); + return -EINVAL; + } + + if (!shdr->num_fdes || !shdr->num_fres) { + pr_debug("no fde/fre entries\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_v3)); + + fres_start = header_end + shdr->fres_off; + fres_end = fres_start + shdr->fre_len; + + if (fres_start < fdes_end || fres_end > sec->sframe_end) { + pr_debug("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; +} + +void __init init_sframe_table(void) +{ + kernel_sfsec.sframe_start = (unsigned long)__start_sframe; + kernel_sfsec.sframe_end = (unsigned long)__end_sframe; + + if (sframe_read_header(&kernel_sfsec)) { + pr_warn("invalid vmlinux SFrame header\n"); + return; + } + + sframe_init = true; +} diff --git a/kernel/unwind/sframe.h b/kernel/unwind/sframe.h new file mode 100644 index 0000000000000..bf895107c2070 --- /dev/null +++ b/kernel/unwind/sframe.h @@ -0,0 +1,78 @@ +/* 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_VERSION_3 3 +#define SFRAME_MAGIC 0xdee2 + +#define SFRAME_F_FDE_SORTED 0x1 +#define SFRAME_F_FRAME_POINTER 0x2 +#define SFRAME_F_FDE_FUNC_START_PCREL 0x4 + +#define SFRAME_ABI_AARCH64_ENDIAN_BIG 1 +#define SFRAME_ABI_AARCH64_ENDIAN_LITTLE 2 +#define SFRAME_ABI_AMD64_ENDIAN_LITTLE 3 + +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; + +struct sframe_fde_v3 { + s64 func_start_off; + u32 func_size; + u32 fres_off; +} __packed; + +struct sframe_fda_v3 { + u16 fres_num; + u8 info; + u8 info2; + u8 rep_size; +} __packed; + +#define SFRAME_FDE_PCTYPE_INC 0 +#define SFRAME_FDE_PCTYPE_MASK 1 + +#define SFRAME_AARCH64_PAUTH_KEY_A 0 +#define SFRAME_AARCH64_PAUTH_KEY_B 1 + +#define SFRAME_V3_FDE_FRE_TYPE(info) ((info) & 0xf) +#define SFRAME_V3_FDE_PCTYPE(info) (((info) >> 4) & 0x1) +#define SFRAME_V3_AARCH64_FDE_PAUTH_KEY(info) (((info) >> 5) & 0x1) + +#define SFRAME_FDE_TYPE_DEFAULT 0 + +#define SFRAME_V3_FDE_TYPE_MASK 0x1f +#define SFRAME_V3_FDE_TYPE(info2) ((info2) & SFRAME_V3_FDE_TYPE_MASK) + +#define SFRAME_BASE_REG_FP 0 +#define SFRAME_BASE_REG_SP 1 + +#define SFRAME_V3_FRE_CFA_BASE_REG_ID(info) ((info) & 0x1) +#define SFRAME_V3_FRE_DATAWORD_COUNT(info) (((info) >> 1) & 0xf) +#define SFRAME_V3_FRE_DATAWORD_SIZE(info) (((info) >> 5) & 0x3) +#define SFRAME_V3_AARCH64_FRE_MANGLED_RA_P(info) (((info) >> 7) & 0x1) + +#endif /* _SFRAME_H */ -- 2.55.0.1082.g2b9226bbc0-goog
