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Subject[tip: core/objtool] scripts/sorttable: Implement build-time ORC unwind table sorting
The following commit has been merged into the core/objtool branch of tip:

Commit-ID: 57fa1899428538e314a7e0d52a5b617af082389a
Gitweb: https://git.kernel.org/tip/57fa1899428538e314a7e0d52a5b617af082389a
Author: Shile Zhang <shile.zhang@linux.alibaba.com>
AuthorDate: Wed, 04 Dec 2019 08:46:32 +08:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Fri, 13 Dec 2019 10:47:58 +01:00

scripts/sorttable: Implement build-time ORC unwind table sorting

The ORC unwinder has two tables: .orc_unwind_ip and .orc_unwind, which
need to be sorted for binary search. Previously this sorting was done
during bootup.

Sort them at build time to speed up booting.

Add the ORC tables sorting in a parallel build process to speed up the build.

[ mingo: Rewrote the changelog and fixed some comments. ]

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Shile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: linux-kbuild@vger.kernel.org
Link: https://lkml.kernel.org/r/20191204004633.88660-7-shile.zhang@linux.alibaba.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
scripts/Makefile | 9 ++-
scripts/sorttable.c | 6 +-
scripts/sorttable.h | 180 +++++++++++++++++++++++++++++++++++++++++--
3 files changed, 189 insertions(+), 6 deletions(-)

diff --git a/scripts/Makefile b/scripts/Makefile
index 7491241..b0e9626 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -24,6 +24,15 @@ HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include
HOSTLDLIBS_sign-file = -lcrypto
HOSTLDLIBS_extract-cert = -lcrypto

+ifdef CONFIG_UNWINDER_ORC
+ifeq ($(ARCH),x86_64)
+ARCH := x86
+endif
+HOSTCFLAGS_sorttable.o += -I$(srctree)/tools/arch/x86/include
+HOSTCFLAGS_sorttable.o += -DUNWINDER_ORC_ENABLED
+HOSTLDLIBS_sorttable = -lpthread
+endif
+
always := $(hostprogs-y) $(hostprogs-m)

# The following hostprogs-y programs are only build on demand
diff --git a/scripts/sorttable.c b/scripts/sorttable.c
index ff98b7d..ec6b5e8 100644
--- a/scripts/sorttable.c
+++ b/scripts/sorttable.c
@@ -2,6 +2,10 @@
/*
* sorttable.c: Sort the kernel's table
*
+ * Added ORC unwind tables sort support and other updates:
+ * Copyright (C) 1999-2019 Alibaba Group Holding Limited. by:
+ * Shile Zhang <shile.zhang@linux.alibaba.com>
+ *
* Copyright 2011 - 2012 Cavium, Inc.
*
* Based on code taken from recortmcount.c which is:
@@ -9,7 +13,7 @@
* Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
*
* Restructured to fit Linux format, as well as other updates:
- * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
+ * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
*/

/*
diff --git a/scripts/sorttable.h b/scripts/sorttable.h
index 82589ff..a2baa2f 100644
--- a/scripts/sorttable.h
+++ b/scripts/sorttable.h
@@ -2,8 +2,15 @@
/*
* sorttable.h
*
+ * Added ORC unwind tables sort support and other updates:
+ * Copyright (C) 1999-2019 Alibaba Group Holding Limited. by:
+ * Shile Zhang <shile.zhang@linux.alibaba.com>
+ *
* Copyright 2011 - 2012 Cavium, Inc.
*
+ * Some of code was taken out of arch/x86/kernel/unwind_orc.c, written by:
+ * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
+ *
* Some of this code was taken out of recordmcount.h written by:
*
* Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
@@ -75,6 +82,104 @@
# define _w w
#endif

+#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
+/* ORC unwinder only support X86_64 */
+#include <errno.h>
+#include <pthread.h>
+#include <asm/orc_types.h>
+
+#define ERRSTR_MAXSZ 256
+
+char g_err[ERRSTR_MAXSZ];
+int *g_orc_ip_table;
+struct orc_entry *g_orc_table;
+
+pthread_t orc_sort_thread;
+
+static inline unsigned long orc_ip(const int *ip)
+{
+ return (unsigned long)ip + *ip;
+}
+
+static int orc_sort_cmp(const void *_a, const void *_b)
+{
+ struct orc_entry *orc_a;
+ const int *a = g_orc_ip_table + *(int *)_a;
+ const int *b = g_orc_ip_table + *(int *)_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 = g_orc_table + (a - g_orc_ip_table);
+ return orc_a->sp_reg == ORC_REG_UNDEFINED && !orc_a->end ? -1 : 1;
+}
+
+static void *sort_orctable(void *arg)
+{
+ int i;
+ int *idxs = NULL;
+ int *tmp_orc_ip_table = NULL;
+ struct orc_entry *tmp_orc_table = NULL;
+ unsigned int *orc_ip_size = (unsigned int *)arg;
+ unsigned int num_entries = *orc_ip_size / sizeof(int);
+ unsigned int orc_size = num_entries * sizeof(struct orc_entry);
+
+ idxs = (int *)malloc(*orc_ip_size);
+ if (!idxs) {
+ snprintf(g_err, ERRSTR_MAXSZ, "malloc idxs: %s",
+ strerror(errno));
+ pthread_exit(g_err);
+ }
+
+ tmp_orc_ip_table = (int *)malloc(*orc_ip_size);
+ if (!tmp_orc_ip_table) {
+ snprintf(g_err, ERRSTR_MAXSZ, "malloc tmp_orc_ip_table: %s",
+ strerror(errno));
+ pthread_exit(g_err);
+ }
+
+ tmp_orc_table = (struct orc_entry *)malloc(orc_size);
+ if (!tmp_orc_table) {
+ snprintf(g_err, ERRSTR_MAXSZ, "malloc tmp_orc_table: %s",
+ strerror(errno));
+ pthread_exit(g_err);
+ }
+
+ /* initialize indices array, convert ip_table to absolute address */
+ for (i = 0; i < num_entries; i++) {
+ idxs[i] = i;
+ tmp_orc_ip_table[i] = g_orc_ip_table[i] + i * sizeof(int);
+ }
+ memcpy(tmp_orc_table, g_orc_table, orc_size);
+
+ qsort(idxs, num_entries, sizeof(int), orc_sort_cmp);
+
+ for (i = 0; i < num_entries; i++) {
+ if (idxs[i] == i)
+ continue;
+
+ /* convert back to relative address */
+ g_orc_ip_table[i] = tmp_orc_ip_table[idxs[i]] - i * sizeof(int);
+ g_orc_table[i] = tmp_orc_table[idxs[i]];
+ }
+
+ free(idxs);
+ free(tmp_orc_ip_table);
+ free(tmp_orc_table);
+ pthread_exit(NULL);
+}
+#endif
+
static int compare_extable(const void *a, const void *b)
{
Elf_Addr av = _r(a);
@@ -91,6 +196,7 @@ static int do_sort(Elf_Ehdr *ehdr,
char const *const fname,
table_sort_t custom_sort)
{
+ int rc = -1;
Elf_Shdr *s, *shdr = (Elf_Shdr *)((char *)ehdr + _r(&ehdr->e_shoff));
Elf_Shdr *strtab_sec = NULL;
Elf_Shdr *symtab_sec = NULL;
@@ -111,6 +217,11 @@ static int do_sort(Elf_Ehdr *ehdr,
int idx;
unsigned int shnum;
unsigned int shstrndx;
+#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
+ unsigned int orc_ip_size = 0;
+ unsigned int orc_size = 0;
+ unsigned int orc_num_entries = 0;
+#endif

shstrndx = r2(&ehdr->e_shstrndx);
if (shstrndx == SHN_XINDEX)
@@ -141,21 +252,61 @@ static int do_sort(Elf_Ehdr *ehdr,
if (r(&s->sh_type) == SHT_SYMTAB_SHNDX)
symtab_shndx = (Elf32_Word *)((const char *)ehdr +
_r(&s->sh_offset));
+
+#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
+ /* locate the ORC unwind tables */
+ if (!strcmp(secstrings + idx, ".orc_unwind_ip")) {
+ orc_ip_size = s->sh_size;
+ g_orc_ip_table = (int *)((void *)ehdr +
+ s->sh_offset);
+ }
+ if (!strcmp(secstrings + idx, ".orc_unwind")) {
+ orc_size = s->sh_size;
+ g_orc_table = (struct orc_entry *)((void *)ehdr +
+ s->sh_offset);
+ }
+#endif
+ } /* for loop */
+
+#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
+ if (!g_orc_ip_table || !g_orc_table) {
+ fprintf(stderr,
+ "incomplete ORC unwind tables in file: %s\n", fname);
+ goto out;
+ }
+
+ orc_num_entries = orc_ip_size / sizeof(int);
+ if (orc_ip_size % sizeof(int) != 0 ||
+ orc_size % sizeof(struct orc_entry) != 0 ||
+ orc_num_entries != orc_size / sizeof(struct orc_entry)) {
+ fprintf(stderr,
+ "inconsistent ORC unwind table entries in file: %s\n",
+ fname);
+ goto out;
}

+ /* create thread to sort ORC unwind tables concurrently */
+ if (pthread_create(&orc_sort_thread, NULL,
+ sort_orctable, &orc_ip_size)) {
+ fprintf(stderr,
+ "pthread_create orc_sort_thread failed '%s': %s\n",
+ strerror(errno), fname);
+ goto out;
+ }
+#endif
if (!extab_sec) {
fprintf(stderr, "no __ex_table in file: %s\n", fname);
- return -1;
+ goto out;
}

if (!symtab_sec) {
fprintf(stderr, "no .symtab in file: %s\n", fname);
- return -1;
+ goto out;
}

if (!strtab_sec) {
fprintf(stderr, "no .strtab in file: %s\n", fname);
- return -1;
+ goto out;
}

extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);
@@ -192,7 +343,7 @@ static int do_sort(Elf_Ehdr *ehdr,
fprintf(stderr,
"no main_extable_sort_needed symbol in file: %s\n",
fname);
- return -1;
+ goto out;
}

sort_needed_sec = &shdr[get_secindex(r2(&sym->st_shndx),
@@ -205,6 +356,25 @@ static int do_sort(Elf_Ehdr *ehdr,

/* extable has been sorted, clear the flag */
w(0, sort_needed_loc);
+ rc = 0;

- return 0;
+out:
+#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
+ if (orc_sort_thread) {
+ void *retval = NULL;
+ /* wait for ORC tables sort done */
+ rc = pthread_join(orc_sort_thread, &retval);
+ if (rc)
+ fprintf(stderr,
+ "pthread_join failed '%s': %s\n",
+ strerror(errno), fname);
+ else if (retval) {
+ rc = -1;
+ fprintf(stderr,
+ "failed to sort ORC tables '%s': %s\n",
+ (char *)retval, fname);
+ }
+ }
+#endif
+ return rc;
}
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