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From: Peter Zijlstra <peterz@infradead.org>
To: tglx@linutronix.de, jpoimboe@redhat.com
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
	peterz@infradead.org, mhiramat@kernel.org, mbenes@suse.cz,
	brgerst@gmail.com
Subject: [PATCH v3 16/26] objtool: Optimize find_rela_by_dest_range()
Date: Tue, 24 Mar 2020 16:31:29 +0100
Message-ID: <20200324160924.861321325@infradead.org> (raw)
In-Reply-To: <20200324153113.098167666@infradead.org>

Perf shows there is significant time in find_rela_by_dest(); this is
because we have to iterate the address space per byte, looking for
relocation entries.

Optimize this by reducing the address space granularity.

This reduces objtool on vmlinux.o runtime from 4.8 to 4.4 seconds.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 tools/objtool/elf.c |   15 +++++++++++----
 tools/objtool/elf.h |   16 +++++++++++++++-
 2 files changed, 26 insertions(+), 5 deletions(-)

--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -215,7 +215,7 @@ struct symbol *find_symbol_by_name(struc
 struct rela *find_rela_by_dest_range(struct elf *elf, struct section *sec,
 				     unsigned long offset, unsigned int len)
 {
-	struct rela *rela;
+	struct rela *rela, *r = NULL;
 	unsigned long o;
 
 	if (!sec->rela)
@@ -223,12 +223,19 @@ struct rela *find_rela_by_dest_range(str
 
 	sec = sec->rela;
 
-	for (o = offset; o < offset + len; o++) {
+	for_offset_range(o, offset, offset + len) {
 		hash_for_each_possible(elf->rela_hash, rela, hash,
 				       sec_offset_hash(sec, o)) {
-			if (rela->sec == sec && rela->offset == o)
-				return rela;
+			if (rela->sec != sec)
+				continue;
+
+			if (rela->offset >= offset && rela->offset < offset + len) {
+				if (!r || rela->offset < r->offset)
+					r = rela;
+			}
 		}
+		if (r)
+			return r;
 	}
 
 	return NULL;
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -83,9 +83,23 @@ struct elf {
 	DECLARE_HASHTABLE(rela_hash, 20);
 };
 
+#define OFFSET_STRIDE_BITS	4
+#define OFFSET_STRIDE		(1UL << OFFSET_STRIDE_BITS)
+#define OFFSET_STRIDE_MASK	(~(OFFSET_STRIDE - 1))
+
+#define for_offset_range(_offset, _start, _end)		\
+	for (_offset = ((_start) & OFFSET_STRIDE_MASK);	\
+	     _offset <= ((_end) & OFFSET_STRIDE_MASK);	\
+	     _offset += OFFSET_STRIDE)
+
 static inline u32 sec_offset_hash(struct section *sec, unsigned long offset)
 {
-	u32 ol = offset, oh = offset >> 32, idx = sec->idx;
+	u32 ol, oh, idx = sec->idx;
+
+	offset &= OFFSET_STRIDE_MASK;
+
+	ol = offset;
+	oh = offset >> 32;
 
 	__jhash_mix(ol, oh, idx);
 



  parent reply index

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24 15:31 [PATCH v3 00/26] objtool: vmlinux.o and noinstr validation Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 01/26] objtool: Introduce validate_return() Peter Zijlstra
2020-03-25  8:39   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 02/26] objtool: Rename func_for_each_insn() Peter Zijlstra
2020-03-25  8:43   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 03/26] objtool: Rename func_for_each_insn_all() Peter Zijlstra
2020-03-25  8:44   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 04/26] x86/kexec: Use RIP relative addressing Peter Zijlstra
2020-03-25  9:34   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 05/26] x86/kexec: Make relocate_kernel_64.S objtool clean Peter Zijlstra
2020-03-24 20:55   ` Josh Poimboeuf
2020-03-25  9:56   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 06/26] objtool: Optimize find_symbol_by_index() Peter Zijlstra
2020-03-25 10:01   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 07/26] objtool: Add a statistics mode Peter Zijlstra
2020-03-25 10:10   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 08/26] objtool: Optimize find_section_by_index() Peter Zijlstra
2020-03-25 10:12   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 09/26] objtool: Optimize find_section_by_name() Peter Zijlstra
2020-03-25 10:18   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 10/26] objtool: Optimize find_symbol_*() and read_symbols() Peter Zijlstra
2020-03-25 10:20   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 11/26] objtool: Rename find_containing_func() Peter Zijlstra
2020-03-25 10:21   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 12/26] objtool: Resize insn_hash Peter Zijlstra
2020-03-25 10:21   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 13/26] objtool: Optimize find_symbol_by_name() Peter Zijlstra
2020-03-25 10:25   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 14/26] objtool: Optimize read_sections() Peter Zijlstra
2020-03-25 12:10   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-04-21 14:47   ` [PATCH v3 14/26] " youling257
2020-04-21 15:49     ` Peter Zijlstra
2020-04-21 15:57       ` Borislav Petkov
2020-04-21 17:50       ` youling 257
2020-03-24 15:31 ` [PATCH v3 15/26] objtool: Delete cleanup() Peter Zijlstra
2020-03-25 12:11   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` Peter Zijlstra [this message]
2020-03-25 12:19   ` [PATCH v3 16/26] objtool: Optimize find_rela_by_dest_range() Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 17/26] objtool: Re-arrange validate_functions() Peter Zijlstra
2020-03-24 21:10   ` Josh Poimboeuf
2020-03-24 21:15     ` Peter Zijlstra
2020-03-25 12:22   ` Miroslav Benes
2020-03-26 10:08   ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 18/26] objtool: Fix !CFI insn_state propagation Peter Zijlstra
2020-03-24 21:40   ` Josh Poimboeuf
2020-03-24 22:11     ` Peter Zijlstra
2020-03-24 23:00       ` Peter Zijlstra
2020-03-25 14:39         ` Josh Poimboeuf
2020-03-25 14:41   ` [PATCH v3.1 18a/26] objtool: Remove CFI save/restore special case Peter Zijlstra
2020-03-25 14:42   ` [PATCH v3.1 18b/26] objtool: Factor out CFI hints Peter Zijlstra
2020-03-25 14:43   ` [PATCH v3.1 18c/26] objtool: Rename struct cfi_state Peter Zijlstra
2020-03-25 14:43   ` [PATCH v3.1 18d/26] objtool: Fix !CFI insn_state propagation Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 19/26] objtool: Implement noinstr validation Peter Zijlstra
2020-03-24 21:41   ` Josh Poimboeuf
2020-03-25 14:44   ` [PATCH v3.1 " Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 20/26] objtool: Optimize !vmlinux.o again Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 21/26] objtool: Use sec_offset_hash() for insn_hash Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 22/26] objtool: Detect loading function pointers across noinstr Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 23/26] kbuild/objtool: Add objtool-vmlinux.o pass Peter Zijlstra
2020-03-24 22:03   ` Josh Poimboeuf
2020-03-24 22:05     ` Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 24/26] objtool: Avoid iterating !text section symbols Peter Zijlstra
2020-03-24 22:09   ` Josh Poimboeuf
2020-03-24 15:31 ` [PATCH v3 25/26] objtool: Rearrange validate_section() Peter Zijlstra
2020-03-24 22:10   ` Josh Poimboeuf
2020-03-24 15:31 ` [PATCH v3 26/26] objtool: Add STT_NOTYPE noinstr validation Peter Zijlstra
2020-03-24 22:16   ` Josh Poimboeuf
2020-03-24 22:34     ` Peter Zijlstra
2020-03-25 14:42       ` Josh Poimboeuf
2020-03-25 15:53         ` Peter Zijlstra
2020-03-25 16:40           ` Josh Poimboeuf
2020-03-25 16:50             ` Peter Zijlstra
2020-03-26  8:01               ` Julien Thierry

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