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From: Matt Helsley <mhelsley@vmware.com>
To: <linux-kernel@vger.kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Sami Tolvanen <samitolvanen@google.com>,
	Julien Thierry <jthierry@redhat.com>,
	Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
	Matt Helsley <mhelsley@vmware.com>
Subject: [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount()
Date: Tue, 2 Jun 2020 12:50:11 -0700	[thread overview]
Message-ID: <7109ceb239a88c2901eeb7f52c29f69cdb413cd3.1591125127.git.mhelsley@vmware.com> (raw)
In-Reply-To: <cover.1591125127.git.mhelsley@vmware.com>

The nop_mcount() function overwrites mcount calls that should be
ignored with no-ops. This operation varies by architecture and
wordsize so we retain the function pointers used to implement
the fundamental operation while nop_mcount() itself is responsible
for walking the relocations, determining if they should be turned
into no-ops, then calling the arch-specific code. Since none of
these use the recordmcount ELF wrappers anymore we can move it out
of the wrapper.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 tools/objtool/recordmcount.c | 47 +++++++++++++++++++++++++++++++++
 tools/objtool/recordmcount.h | 50 ------------------------------------
 2 files changed, 47 insertions(+), 50 deletions(-)

diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 89762908290e..88998a505859 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -398,6 +398,53 @@ static int find_section_sym_index(unsigned const txtndx,
 	return missing_sym;
 }
 
+/*
+ * Read the relocation table again, but this time its called on sections
+ * that are not going to be traced. The mcount calls here will be converted
+ * into nops.
+ */
+static int nop_mcount(struct section * const rels,
+		      const char *const txtname)
+{
+	struct reloc *reloc;
+	struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
+	unsigned mcountsym = 0;
+	int once = 0;
+
+	list_for_each_entry(reloc, &rels->reloc_list, list) {
+		int ret = -1;
+
+		if (!mcountsym)
+			mcountsym = get_mcountsym(reloc);
+
+		if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
+			if (make_nop) {
+				ret = make_nop(txts, reloc->offset);
+				if (ret < 0)
+					return -1;
+			}
+			if (warn_on_notrace_sect && !once) {
+				printf("Section %s has mcount callers being ignored\n",
+				       txtname);
+				once = 1;
+				/* just warn? */
+				if (!make_nop)
+					return 0;
+			}
+		}
+
+		/*
+		 * If we successfully removed the mcount, mark the relocation
+		 * as a nop (don't do anything with it).
+		 */
+		if (!ret) {
+			reloc->type = rel_type_nop;
+			rels->changed = true;
+		}
+	}
+	return 0;
+}
+
 /* 32 bit and 64 bit are very similar */
 #include "recordmcount.h"
 #define RECORD_MCOUNT_64
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index 6754bde0bacc..e033b600bd61 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -20,7 +20,6 @@
 #undef append_func
 #undef mcount_adjust
 #undef sift_rel_mcount
-#undef nop_mcount
 #undef has_rel_mcount
 #undef tot_relsize
 #undef do_func
@@ -37,7 +36,6 @@
 #ifdef RECORD_MCOUNT_64
 # define append_func		append64
 # define sift_rel_mcount	sift64_rel_mcount
-# define nop_mcount		nop_mcount_64
 # define has_rel_mcount		has64_rel_mcount
 # define tot_relsize		tot64_relsize
 # define do_func		do64
@@ -53,7 +51,6 @@
 #else
 # define append_func		append32
 # define sift_rel_mcount	sift32_rel_mcount
-# define nop_mcount		nop_mcount_32
 # define has_rel_mcount		has32_rel_mcount
 # define tot_relsize		tot32_relsize
 # define do_func		do32
@@ -171,53 +168,6 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
 	return mlocp;
 }
 
-/*
- * Read the relocation table again, but this time its called on sections
- * that are not going to be traced. The mcount calls here will be converted
- * into nops.
- */
-static int nop_mcount(struct section * const rels,
-		      const char *const txtname)
-{
-	struct reloc *reloc;
-	struct section *txts = find_section_by_index(lf, rels->sh.sh_info);
-	unsigned mcountsym = 0;
-	int once = 0;
-
-	list_for_each_entry(reloc, &rels->reloc_list, list) {
-		int ret = -1;
-
-		if (!mcountsym)
-			mcountsym = get_mcountsym(reloc);
-
-		if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) {
-			if (make_nop) {
-				ret = make_nop(txts, reloc->offset);
-				if (ret < 0)
-					return -1;
-			}
-			if (warn_on_notrace_sect && !once) {
-				printf("Section %s has mcount callers being ignored\n",
-				       txtname);
-				once = 1;
-				/* just warn? */
-				if (!make_nop)
-					return 0;
-			}
-		}
-
-		/*
-		 * If we successfully removed the mcount, mark the relocation
-		 * as a nop (don't do anything with it).
-		 */
-		if (!ret) {
-			reloc->type = rel_type_nop;
-			rels->changed = true;
-		}
-	}
-	return 0;
-}
-
 static char const *has_rel_mcount(const struct section * const rels)
 {
 	const struct section *txts;
-- 
2.20.1


  parent reply	other threads:[~2020-06-02 19:52 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-02 19:49 [RFC][PATCH v4 00/32] objtool: Make recordmcount a subcommand Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 01/32] objtool: Prepare to merge recordmcount Matt Helsley
2020-06-09  8:54   ` Julien Thierry
2020-06-09 15:42     ` Matt Helsley
2020-06-09 19:31       ` Julien Thierry
2020-06-02 19:49 ` [RFC][PATCH v4 02/32] objtool: Make recordmcount into mcount subcmd Matt Helsley
2020-06-09  9:00   ` Julien Thierry
2020-06-09 18:39     ` Matt Helsley
2020-06-09 18:52       ` Steven Rostedt
2020-06-09 18:56         ` Matt Helsley
2020-06-09 19:11       ` Julien Thierry
2020-06-02 19:49 ` [RFC][PATCH v4 03/32] objtool: recordmcount: Start using objtool's elf wrapper Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 04/32] objtool: recordmcount: Search for __mcount_loc before walking the sections Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 05/32] objtool: recordmcount: Convert do_func() relhdrs Matt Helsley
2020-06-02 19:49 ` [RFC][PATCH v4 06/32] objtool: mcount: Remove unused fname parameter Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 07/32] objtool: mcount: Use libelf for section header names Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 08/32] objtool: mcount: Walk objtool Elf structs in find_secsym_ndx Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 09/32] objtool: mcount: Use symbol structs to find mcount relocations Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 10/32] objtool: mcount: Walk relocation lists Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 11/32] objtool: mcount: Move get_mcountsym Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 12/32] objtool: mcount: Replace MIPS offset types Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 13/32] objtool: mcount: Move is_fake_mcount() Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 14/32] objtool: mcount: Stop using ehdr in find_section_sym_index Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 15/32] objtool: mcount: Move find_section_sym_index() Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 16/32] objtool: mcount: Restrict using ehdr in append_func() Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 17/32] objtool: mcount: Use objtool ELF to write Matt Helsley
2020-06-02 19:50 ` Matt Helsley [this message]
2020-06-12 13:26   ` [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount() Peter Zijlstra
2020-06-12 16:05     ` Peter Zijlstra
2020-06-17 17:36       ` Matt Helsley
2020-06-17 18:30         ` Peter Zijlstra
2020-06-13 19:49     ` Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 19/32] objtool: mcount: Move has_rel_mcount() and tot_relsize() Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 20/32] objtool: mcount: Move relocation entry size detection Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 21/32] objtool: mcount: Only keep ELF file size Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 22/32] objtool: mcount: Use ELF header from objtool Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 23/32] objtool: mcount: Remove unused file mapping Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 24/32] objtool: mcount: Reduce usage of _size wrapper Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 25/32] objtool: mcount: Move mcount_adjust out of wrapper Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 26/32] objtool: mcount: Pre-allocate new ELF sections Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 27/32] objtool: mcount: Generic location and relocation table types Matt Helsley
2020-06-09  6:41   ` Kamalesh Babulal
2020-06-09 18:12     ` Matt Helsley
2020-06-10  4:35       ` Kamalesh Babulal
2020-06-02 19:50 ` [RFC][PATCH v4 28/32] objtool: mcount: Move sift_rel_mcount out of wrapper file Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 29/32] objtool: mcount: Remove wrapper for ELF relocation type Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 30/32] objtool: mcount: Remove wrapper double-include trick Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 31/32] objtool: mcount: Remove endian wrappers Matt Helsley
2020-06-02 19:50 ` [RFC][PATCH v4 32/32] objtool: mcount: Rename Matt Helsley

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