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Subject[RFC PATCH v2 1/3] scripts: Add sortorctable to sort ORC unwind tables
Date
From: Shile Zhang <shile.zhang@linux.alibaba.com>

Sort orc_unwind and orc_unwind_ip tables at build time instead of runtime
in boot pharse can save more boot time.

Signed-off-by: Shile Zhang <shile.zhang@linux.alibaba.com>
---
scripts/.gitignore | 1 +
scripts/Makefile | 2 +
scripts/sortorctable.c | 251 +++++++++++++++++++++++++++++++++++++++++
scripts/sortorctable.h | 26 +++++
4 files changed, 280 insertions(+)
create mode 100644 scripts/sortorctable.c
create mode 100644 scripts/sortorctable.h

diff --git a/scripts/.gitignore b/scripts/.gitignore
index 17f8cef88fa8..52976f32f974 100644
--- a/scripts/.gitignore
+++ b/scripts/.gitignore
@@ -12,3 +12,4 @@ asn1_compiler
extract-cert
sign-file
insert-sys-cert
+sortorctable
diff --git a/scripts/Makefile b/scripts/Makefile
index 3e86b300f5a1..4473f8d7da0c 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -16,12 +16,14 @@ hostprogs-$(CONFIG_LOGO) += pnmtologo
hostprogs-$(CONFIG_VT) += conmakehash
hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable
+hostprogs-$(CONFIG_UNWINDER_ORC) += sortorctable
hostprogs-$(CONFIG_ASN1) += asn1_compiler
hostprogs-$(CONFIG_MODULE_SIG_FORMAT) += sign-file
hostprogs-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += extract-cert
hostprogs-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE) += insert-sys-cert

HOSTCFLAGS_sortextable.o = -I$(srctree)/tools/include
+HOSTCFLAGS_sortorctable.o = -I$(srctree)/tools/include
HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include
HOSTLDLIBS_sign-file = -lcrypto
HOSTLDLIBS_extract-cert = -lcrypto
diff --git a/scripts/sortorctable.c b/scripts/sortorctable.c
new file mode 100644
index 000000000000..193e06ac2632
--- /dev/null
+++ b/scripts/sortorctable.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * sortorctable: used to sort the ORC unwind tables
+ *
+ * Copyright (C) 2019 Alibaba Group Holding Limited. All rights reserved.
+ * Written by Shile Zhang <shile.zhang@linux.alibaba.com>
+ *
+ * Some code taken out of lib/sort.c and
+ * arch/x86/kernel/unwind_orc.c written by:
+ * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ *
+ * Strategy: alter the vmlinux file in-place
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include <elf.h>
+
+#include "sortorctable.h"
+
+int *cur_orc_ip_table;
+struct orc_entry *cur_orc_table;
+
+/**
+ * sort - sort an array of elements
+ * @base: pointer to data to sort
+ * @num: number of elements
+ * @size: size of each element
+ * @cmp_func: pointer to comparison function
+ * @swap_func: pointer to swap function
+ *
+ * This function does a heapsort on the given array. You may provide a
+ * swap_func function optimized to your element type.
+ *
+ * Sorting time is O(n log n) both on average and worst-case. While
+ * qsort is about 20% faster on average, it suffers from exploitable
+ * O(n*n) worst-case behavior and extra memory requirements that make
+ * it less suitable for kernel use.
+ */
+static void sort(void *base, size_t num, size_t size,
+ int (*cmp_func)(const void *, const void *),
+ void (*swap_func)(void *, void *, int size))
+{
+ /* pre-scale counters for performance */
+ int i = (num/2 - 1) * size, n = num * size, c, r;
+
+ /* heapify */
+ for ( ; i >= 0; i -= size) {
+ for (r = i; r * 2 + size < n; r = c) {
+ c = r * 2 + size;
+ if (c < n - size &&
+ cmp_func(base + c, base + c + size) < 0)
+ c += size;
+ if (cmp_func(base + r, base + c) >= 0)
+ break;
+ swap_func(base + r, base + c, size);
+ }
+ }
+
+ /* sort */
+ for (i = n - size; i > 0; i -= size) {
+ swap_func(base, base + i, size);
+ for (r = 0; r * 2 + size < i; r = c) {
+ c = r * 2 + size;
+ if (c < i - size &&
+ cmp_func(base + c, base + c + size) < 0)
+ c += size;
+ if (cmp_func(base + r, base + c) >= 0)
+ break;
+ swap_func(base + r, base + c, size);
+ }
+ }
+}
+
+static inline unsigned long orc_ip(const int *ip)
+{
+ return (unsigned long)ip + *ip;
+}
+
+static void orc_sort_swap(void *_a, void *_b, int size)
+{
+ struct orc_entry *orc_a, *orc_b;
+ struct orc_entry orc_tmp;
+ int *a = _a, *b = _b, tmp;
+ int delta = _b - _a;
+
+ /* Swap the .orc_unwind_ip entries: */
+ tmp = *a;
+ *a = *b + delta;
+ *b = tmp - delta;
+
+ /* Swap the corresponding .orc_unwind entries: */
+ orc_a = cur_orc_table + (a - cur_orc_ip_table);
+ orc_b = cur_orc_table + (b - cur_orc_ip_table);
+ orc_tmp = *orc_a;
+ *orc_a = *orc_b;
+ *orc_b = orc_tmp;
+}
+
+static int orc_sort_cmp(const void *_a, const void *_b)
+{
+ struct orc_entry *orc_a;
+ const int *a = _a, *b = _b;
+ unsigned long a_val = orc_ip(a);
+ unsigned long b_val = orc_ip(b);
+
+ if (a_val > b_val)
+ return 1;
+ if (a_val < b_val)
+ return -1;
+
+ /*
+ * The "weak" section terminator entries need to always be on the left
+ * to ensure the lookup code skips them in favor of real entries.
+ * These terminator entries exist to handle any gaps created by
+ * whitelisted .o files which didn't get objtool generation.
+ */
+ orc_a = cur_orc_table + (a - cur_orc_ip_table);
+ return orc_a->sp_reg == ORC_REG_UNDEFINED && !orc_a->end ? -1 : 1;
+}
+
+/* ORC unwind only supports X86_64 */
+static int do_precheck(const char *fname, void *addr)
+{
+ Elf64_Ehdr * const ehdr = addr;
+
+ if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB) {
+ fprintf(stderr, "%s: unsupported ELF data encoding %d\n",
+ fname, ehdr->e_ident[EI_DATA]);
+ return 1;
+ }
+
+ if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
+ || (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN)
+ || ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
+ fprintf(stderr,
+ "%s: unrecognized ET_EXEC/ET_DYN file\n", fname);
+ return 1;
+ }
+
+ if (ehdr->e_machine != EM_X86_64) {
+ fprintf(stderr, "%s: unsupported e_machine %d\n",
+ fname, ehdr->e_machine);
+ return 1;
+ }
+
+ if (ehdr->e_ident[EI_CLASS] != ELFCLASS64
+ || ehdr->e_ehsize != sizeof(Elf64_Ehdr)
+ || ehdr->e_shentsize != sizeof(Elf64_Shdr)) {
+ fprintf(stderr, "%s: unrecognized ELF class %d\n",
+ fname, ehdr->e_ident[EI_CLASS]);
+ return 1;
+ }
+
+ return 0;
+}
+
+static int do_sort(const char *fname, void *addr)
+{
+ unsigned int orc_size, orc_ip_size, num_entries;
+ const Elf64_Shdr *s, *_orc = NULL, *_orc_ip = NULL;
+ Elf64_Ehdr * const ehdr = (Elf64_Ehdr *)addr;
+ Elf64_Shdr * const shdr = (Elf64_Shdr *)((void *)ehdr + ehdr->e_shoff);
+ char *secstrings = (void *)ehdr + shdr[ehdr->e_shstrndx].sh_offset;
+
+ for (s = shdr; s < shdr + ehdr->e_shnum; s++) {
+ if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
+ _orc_ip = s;
+ if (!strcmp(".orc_unwind", secstrings + s->sh_name))
+ _orc = s;
+ }
+
+ if (!_orc_ip || !_orc) {
+ fprintf(stderr,
+ "%s: cannot find ORC unwind tables\n", fname);
+ return 1;
+ }
+
+ orc_size = _orc->sh_size;
+ orc_ip_size = _orc_ip->sh_size;
+ num_entries = orc_ip_size / sizeof(int);
+ cur_orc_table = (struct orc_entry *)((void *)ehdr + _orc->sh_offset);
+ cur_orc_ip_table = (int *)((void *)ehdr + _orc_ip->sh_offset);
+
+ if (orc_ip_size % sizeof(int) != 0
+ || orc_size % sizeof(struct orc_entry) != 0
+ || num_entries != orc_size / sizeof(struct orc_entry)) {
+ fprintf(stderr,
+ "%s: wrong ORC unwind table entries number\n", fname);
+ return 1;
+ }
+
+ sort(cur_orc_ip_table, num_entries, sizeof(int), orc_sort_cmp,
+ orc_sort_swap);
+
+ return 0;
+}
+
+int main(int argc, char *argv[])
+{
+ int ret = 0;
+ int fd;
+ char *fname = NULL;
+ struct stat sb;
+ void *addr = NULL;
+
+ if (argc != 2) {
+ fprintf(stderr, "usage: sortorctable vmlinux\n");
+ return 0;
+ }
+
+ fname = argv[1];
+ fd = open(fname, O_RDWR);
+ if (fd < 0 || fstat(fd, &sb) < 0) {
+ perror(fname);
+ return errno;
+ }
+
+ if (!S_ISREG(sb.st_mode)) {
+ fprintf(stderr, "'%s': not a regular file\n", fname);
+ close(fd);
+ return 1;
+ }
+
+ addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+ if (addr == MAP_FAILED) {
+ fprintf(stderr, "'%s': mmap failed\n", fname);
+ close(fd);
+ return 1;
+ }
+
+ ret = do_precheck(fname, addr);
+ if (ret)
+ goto out;
+
+ ret = do_sort(fname, addr);
+
+out:
+ munmap(addr, sb.st_size);
+ close(fd);
+
+ return ret;
+}
diff --git a/scripts/sortorctable.h b/scripts/sortorctable.h
new file mode 100644
index 000000000000..af82391c70e6
--- /dev/null
+++ b/scripts/sortorctable.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019 Alibaba Group Holding Limited. All rights reserved.
+ * Written by Shile Zhang <shile.zhang@linux.alibaba.com>
+ *
+ * This code was taken out of arch/x86/include/asm/orc_types.h written by:
+ * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ */
+
+#ifndef _SORTORCTABLE_H_
+#define _SORTORCTABLE_H_
+
+#include <linux/types.h>
+
+#define ORC_REG_UNDEFINED 0
+
+struct orc_entry {
+ s16 sp_offset;
+ s16 bp_offset;
+ unsigned sp_reg:4;
+ unsigned bp_reg:4;
+ unsigned type:2;
+ unsigned end:1;
+} __attribute__((packed));
+
+#endif//_SORTORCTABLE_H_
--
2.24.0.rc2
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