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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 25/32] objtool: mcount: Move mcount_adjust out of wrapper
Date: Tue, 2 Jun 2020 12:50:18 -0700	[thread overview]
Message-ID: <7ccc13efc69cb327a44908951d1de7cf4f8bd9a6.1591125127.git.mhelsley@vmware.com> (raw)
In-Reply-To: <cover.1591125127.git.mhelsley@vmware.com>

The mcount_adjust variable defines how many bytes to move back
from the relocation address in order to be able to get to the
start of the function call instruction(s) needed to turn it
into a no-op. The values are very small and signed so we don't
need to worry about changing the size of the variable's type
inside the wrapper -- we can just use a regular int.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 tools/objtool/recordmcount.c | 12 +++++++++---
 tools/objtool/recordmcount.h |  5 -----
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 5ec44c9f2884..06a8f8ddefa7 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -385,6 +385,12 @@ static unsigned tot_relsize(unsigned int *rel_entsize)
 	}
 	return totrelsz;
 }
+
+/* zero or a small negative offset added to get the start of the call
+ * instruction
+ */
+static int mcount_adjust = 0;
+
 /* 32 bit and 64 bit are very similar */
 #include "recordmcount.h"
 #define RECORD_MCOUNT_64
@@ -495,7 +501,7 @@ static int do_file(char const *const fname)
 		rel_type_nop = R_386_NONE;
 		make_nop = make_nop_x86;
 		ideal_nop = ideal_nop5_x86_32;
-		mcount_adjust_32 = -1;
+		mcount_adjust = -1;
 		gpfx = 0;
 		break;
 	case EM_ARM:
@@ -524,7 +530,7 @@ static int do_file(char const *const fname)
 		ideal_nop = ideal_nop5_x86_64;
 		reltype = R_X86_64_64;
 		rel_type_nop = R_X86_64_NONE;
-		mcount_adjust_64 = -1;
+		mcount_adjust = -1;
 		gpfx = 0;
 		break;
 	}  /* end switch */
@@ -556,7 +562,7 @@ static int do_file(char const *const fname)
 		}
 		if (lf->ehdr.e_machine == EM_S390) {
 			reltype = R_390_64;
-			mcount_adjust_64 = -14;
+			mcount_adjust = -14;
 		}
 		if (lf->ehdr.e_machine == EM_MIPS) {
 			reltype = R_MIPS_64;
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index e2de71f99566..853c4006a34f 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -18,7 +18,6 @@
  * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
  */
 #undef append_func
-#undef mcount_adjust
 #undef sift_rel_mcount
 #undef do_func
 #undef Elf_Shdr
@@ -35,7 +34,6 @@
 # define append_func		append64
 # define sift_rel_mcount	sift64_rel_mcount
 # define do_func		do64
-# define mcount_adjust		mcount_adjust_64
 # define Elf_Rel		Elf64_Rel
 # define Elf_Rela		Elf64_Rela
 # define ELF_R_INFO		ELF64_R_INFO
@@ -48,7 +46,6 @@
 # define append_func		append32
 # define sift_rel_mcount	sift32_rel_mcount
 # define do_func		do32
-# define mcount_adjust		mcount_adjust_32
 # define Elf_Rel		Elf32_Rel
 # define Elf_Rela		Elf32_Rela
 # define ELF_R_INFO		ELF32_R_INFO
@@ -65,8 +62,6 @@ static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
 }
 static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
 
-static int mcount_adjust = 0;
-
 /* Append the new  __mcount_loc and its relocations. */
 static int append_func(uint_t const *const mloc0,
 			uint_t const *const mlocp,
-- 
2.20.1


  parent reply	other threads:[~2020-06-02 19:51 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 ` [RFC][PATCH v4 18/32] objtool: mcount: Move nop_mcount() Matt Helsley
2020-06-12 13:26   ` 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 ` Matt Helsley [this message]
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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