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Date:   Wed,  9 Feb 2022 19:57:43 +0100
From:   Alexander Lobakin <alexandr.lobakin@...el.com>
To:     linux-hardening@...r.kernel.org, x86@...nel.org
Cc:     Alexander Lobakin <alexandr.lobakin@...el.com>,
        Borislav Petkov <bp@...en8.de>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Kristen Carlson Accardi <kristen@...ux.intel.com>,
        Kees Cook <keescook@...omium.org>,
        Miklos Szeredi <miklos@...redi.hu>,
        Ard Biesheuvel <ardb@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        Bruce Schlobohm <bruce.schlobohm@...el.com>,
        Jessica Yu <jeyu@...nel.org>,
        kernel test robot <lkp@...el.com>,
        Miroslav Benes <mbenes@...e.cz>,
        Evgenii Shatokhin <eshatokhin@...tuozzo.com>,
        Jonathan Corbet <corbet@....net>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        Christoph Hellwig <hch@....de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnd Bergmann <arnd@...db.de>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Marios Pomonis <pomonis@...gle.com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        "H.J. Lu" <hjl.tools@...il.com>, Nicolas Pitre <nico@...xnic.net>,
        linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
        linux-arch@...r.kernel.org, live-patching@...r.kernel.org,
        llvm@...ts.linux.dev
Subject: [PATCH v10 06/15] x86: decouple ORC table sorting into a separate file

In order to be able to sort ORC entries from both the kernel and
the pre-boot compressed environment, place ORC sorting function
into the new file arch/x86/lib/orc.c.
It can be then included directly by the pre-boot code, and
ORC_COMPRESSED_BOOT definition guards out the sort_mutex which
is unavailable and unneeded in that environment.

Placing orc_ip() into `include/asm/orc_types.h` wipes out
sorttable.h's little code dup.

Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Alexander Lobakin <alexandr.lobakin@...el.com>
---
 arch/x86/include/asm/orc_types.h       |  7 +++
 arch/x86/kernel/unwind_orc.c           | 63 +--------------------
 arch/x86/lib/Makefile                  |  3 +
 arch/x86/lib/orc.c                     | 78 ++++++++++++++++++++++++++
 scripts/sorttable.h                    |  5 --
 tools/arch/x86/include/asm/orc_types.h |  7 +++
 6 files changed, 96 insertions(+), 67 deletions(-)
 create mode 100644 arch/x86/lib/orc.c

diff --git a/arch/x86/include/asm/orc_types.h b/arch/x86/include/asm/orc_types.h
index 5a2baf28a1dc..7708548713c4 100644
--- a/arch/x86/include/asm/orc_types.h
+++ b/arch/x86/include/asm/orc_types.h
@@ -67,6 +67,13 @@ struct orc_entry {
 #endif
 } __packed;
 
+static inline unsigned long orc_ip(const int *ip)
+{
+	return (unsigned long)ip + *ip;
+}
+
+void orc_sort(int *ip_table, struct orc_entry *orc_table, u32 num_orcs);
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ORC_TYPES_H */
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 2de3c8c5eba9..e5748bf15966 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -25,11 +25,6 @@ extern struct orc_entry __stop_orc_unwind[];
 static bool orc_init __ro_after_init;
 static unsigned int lookup_num_blocks __ro_after_init;
 
-static inline unsigned long orc_ip(const int *ip)
-{
-	return (unsigned long)ip + *ip;
-}
-
 static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table,
 				    unsigned int num_entries, unsigned long ip)
 {
@@ -188,53 +183,6 @@ static struct orc_entry *orc_find(unsigned long ip)
 }
 
 #ifdef CONFIG_MODULES
-
-static DEFINE_MUTEX(sort_mutex);
-static int *cur_orc_ip_table = __start_orc_unwind_ip;
-static struct orc_entry *cur_orc_table = __start_orc_unwind;
-
-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;
-}
-
 void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size,
 			void *_orc, size_t orc_size)
 {
@@ -246,16 +194,7 @@ void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size,
 		     orc_size % sizeof(*orc) != 0 ||
 		     num_entries != orc_size / sizeof(*orc));
 
-	/*
-	 * The 'cur_orc_*' globals allow the orc_sort_swap() callback to
-	 * associate an .orc_unwind_ip table entry with its corresponding
-	 * .orc_unwind entry so they can both be swapped.
-	 */
-	mutex_lock(&sort_mutex);
-	cur_orc_ip_table = orc_ip;
-	cur_orc_table = orc;
-	sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swap);
-	mutex_unlock(&sort_mutex);
+	orc_sort(orc_ip, orc, num_entries);
 
 	mod->arch.orc_unwind_ip = orc_ip;
 	mod->arch.orc_unwind = orc;
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index f76747862bd2..ff094cecebc4 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -50,6 +50,9 @@ lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o insn-eval.o
 lib-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
 lib-$(CONFIG_FUNCTION_ERROR_INJECTION)	+= error-inject.o
 lib-$(CONFIG_RETPOLINE) += retpoline.o
+ifdef CONFIG_MODULES
+lib-$(CONFIG_UNWINDER_ORC) += orc.o
+endif
 
 obj-y += msr.o msr-reg.o msr-reg-export.o hweight.o
 obj-y += iomem.o
diff --git a/arch/x86/lib/orc.c b/arch/x86/lib/orc.c
new file mode 100644
index 000000000000..6a42842bf4ef
--- /dev/null
+++ b/arch/x86/lib/orc.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ORC sorting shared by the compressed boot code and ORC module
+ * support.
+ */
+
+#include <asm/orc_types.h>
+#include <linux/mutex.h>
+#include <linux/sort.h>
+
+#ifndef ORC_COMPRESSED_BOOT
+static DEFINE_MUTEX(sort_mutex);
+
+#define sort_mutex_lock()	mutex_lock(&sort_mutex)
+#define sort_mutex_unlock()	mutex_unlock(&sort_mutex)
+#else /* ORC_COMPRESSED_BOOT */
+#define sort_mutex_lock()
+#define sort_mutex_unlock()
+#endif /* ORC_COMPRESSED_BOOT */
+
+static int *cur_orc_ip_table;
+static struct orc_entry *cur_orc_table;
+
+static void orc_sort_swap(void *_a, void *_b, int size)
+{
+	struct orc_entry *orc_a, *orc_b;
+	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);
+	swap(*orc_a, *orc_b);
+}
+
+static int orc_sort_cmp(const void *_a, const void *_b)
+{
+	const int *a = _a, *b = _b;
+	unsigned long a_val = orc_ip(a);
+	unsigned long b_val = orc_ip(b);
+	struct orc_entry *orc_a;
+
+	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;
+}
+
+void orc_sort(int *ip_table, struct orc_entry *orc_table, u32 num_orcs)
+{
+	/*
+	 * The 'cur_orc_*' globals allow the orc_sort_swap() callback to
+	 * associate an .orc_unwind_ip table entry with its corresponding
+	 * .orc_unwind entry so they can both be swapped.
+	 */
+	sort_mutex_lock();
+
+	cur_orc_ip_table = ip_table;
+	cur_orc_table = orc_table;
+	sort(ip_table, num_orcs, sizeof(int), orc_sort_cmp, orc_sort_swap);
+
+	sort_mutex_unlock();
+}
diff --git a/scripts/sorttable.h b/scripts/sorttable.h
index deb7c1d3e979..a6bb46f36854 100644
--- a/scripts/sorttable.h
+++ b/scripts/sorttable.h
@@ -103,11 +103,6 @@ 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;
diff --git a/tools/arch/x86/include/asm/orc_types.h b/tools/arch/x86/include/asm/orc_types.h
index 5a2baf28a1dc..7708548713c4 100644
--- a/tools/arch/x86/include/asm/orc_types.h
+++ b/tools/arch/x86/include/asm/orc_types.h
@@ -67,6 +67,13 @@ struct orc_entry {
 #endif
 } __packed;
 
+static inline unsigned long orc_ip(const int *ip)
+{
+	return (unsigned long)ip + *ip;
+}
+
+void orc_sort(int *ip_table, struct orc_entry *orc_table, u32 num_orcs);
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ORC_TYPES_H */
-- 
2.34.1

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