[tip: core/objtool] x86/unwind/orc: Remove boot-time ORC unwind tables sorting

[tip-bot2 for Shile Zhang]

The following commit has been merged into the core/objtool branch of tip:

Commit-ID:     f14bf6a350dfd6613dbf91be5b423bc7eab690da
Gitweb:        https://git.kernel.org/tip/f14bf6a350dfd6613dbf91be5b423bc7eab690da
Author:        Shile Zhang <shile.zhang@xxxxxxxxxxxxxxxxx>
AuthorDate:    Wed, 04 Dec 2019 08:46:33 +08:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 13 Dec 2019 10:47:58 +01:00

x86/unwind/orc: Remove boot-time ORC unwind tables sorting

Now that the orc_unwind and orc_unwind_ip tables are sorted at build time,
remove the boot time sorting pass.

No change in functionality.

[ mingo: Rewrote the changelog and code comments. ]

Signed-off-by: Shile Zhang <shile.zhang@xxxxxxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: linux-kbuild@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20191204004633.88660-8-shile.zhang@xxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/kernel/unwind_orc.c | 8 +++++---
 scripts/link-vmlinux.sh      | 5 ++++-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 332ae65..abdf891 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -273,9 +273,11 @@ void __init unwind_init(void)
 		return;
 	}
 
-	/* Sort the .orc_unwind and .orc_unwind_ip tables: */
-	sort(__start_orc_unwind_ip, num_entries, sizeof(int), orc_sort_cmp,
-	     orc_sort_swap);
+	/*
+	 * Note, the orc_unwind and orc_unwind_ip tables were already
+	 * sorted at build time via the 'sorttable' tool.
+	 * It's ready for binary search straight away, no need to sort it.
+	 */
 
 	/* Initialize the fast lookup table: */
 	lookup_num_blocks = orc_lookup_end - orc_lookup;
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index a81aa76..c287ad9 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -306,7 +306,10 @@ vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
 
 if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
 	info SORTTAB vmlinux
-	sorttable vmlinux
+	if ! sorttable vmlinux; then
+		echo >&2 Failed to sort kernel tables
+		exit 1
+	fi
 fi
 
 info SYSMAP System.map