Add C version of recordmcount for MIPS

From: Wu Zhangjin <[email protected]>

MIPS64 has 'weird' Elf64_Rel.r_info[1,2], which must be used instead of the generic Elf64_Rel.r_info, otherwise, the C version of recordmcount will not work for "segmentation fault".

----
[1] http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
[2] arch/mips/include/asm/module.h

Signed-off-by John Reiser <[email protected]>

Signed-off-by Maciej W. Rozycki <[email protected]>

Tested-by Wu Zhangjin <[email protected]>

---
 scripts/recordmcount.c |   41 +++++++++++++++++++++++++++++++++++++++++
 scripts/recordmcount.h |   34 ++++++++++++++++++++++++++++++----
 2 files changed, 71 insertions(+), 4 deletions(-)

scripts/recordmcount.c +41 -0

index 26e1271..2d32b9c 100644
@@ -217,6 +217,39 @@ is_mcounted_section_name(char const *const txtname)
 #define RECORD_MCOUNT_64
 #include "recordmcount.h"
 
+/* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
+ * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
+ * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
+ * to imply the order of the members; the spec does not say so.
+ *	typedef unsigned char Elf64_Byte;
+ * fails on MIPS64 because their <elf.h> already has it!
+ */
+
+typedef uint8_t myElf64_Byte;		/* Type for a 8-bit quantity.  */
+
+union mips_r_info {
+	Elf64_Xword r_info;
+	struct {
+		Elf64_Word r_sym;		/* Symbol index.  */
+		myElf64_Byte r_ssym;		/* Special symbol.  */
+		myElf64_Byte r_type3;		/* Third relocation.  */
+		myElf64_Byte r_type2;		/* Second relocation.  */
+		myElf64_Byte r_type;		/* First relocation.  */
+	} r_mips;
+};
+
+static uint64_t MIPS64_r_sym(Elf64_Rel const *rp)
+{
+	return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym);
+}
+
+static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
+{
+	rp->r_info = ((union mips_r_info){
+		.r_mips = { .r_sym = w(sym), .r_type = type }
+	}).r_info;
+}
+
 static void
 do_file(char const *const fname)
 {

@@ -268,6 +301,7 @@ do_file(char const *const fname)
 	case EM_386:	 reltype = R_386_32;                   break;
 	case EM_ARM:	 reltype = R_ARM_ABS32;                break;
 	case EM_IA_64:	 reltype = R_IA64_IMM64;   gpfx = '_'; break;
+	case EM_MIPS:	 /* reltype: e_class    */ gpfx = '_'; break;
 	case EM_PPC:	 reltype = R_PPC_ADDR32;   gpfx = '_'; break;
 	case EM_PPC64:	 reltype = R_PPC64_ADDR64; gpfx = '_'; break;
 	case EM_S390:    /* reltype: e_class    */ gpfx = '_'; break;

@@ -291,6 +325,8 @@ do_file(char const *const fname)
 		}
 		if (EM_S390 == w2(ehdr->e_machine))
 			reltype = R_390_32;
+		if (EM_MIPS == w2(ehdr->e_machine))
+			reltype = R_MIPS_32;
 		do32(ehdr, fname, reltype);
 	} break;
 	case ELFCLASS64: {

@@ -303,6 +339,11 @@ do_file(char const *const fname)
 		}
 		if (EM_S390 == w2(ghdr->e_machine))
 			reltype = R_390_64;
+		if (EM_MIPS == w2(ghdr->e_machine)) {
+			reltype = R_MIPS_64;
+			Elf64_r_sym = MIPS64_r_sym;
+			Elf64_r_info = MIPS64_r_info;
+		}
 		do64(ghdr, fname, reltype);
 	} break;
 	}  /* end switch */

scripts/recordmcount.h +30 -4

index 7f39d09..190fd18 100644
@@ -31,8 +31,12 @@
 #undef Elf_Rela
 #undef Elf_Sym
 #undef ELF_R_SYM
+#undef Elf_r_sym
 #undef ELF_R_INFO
+#undef Elf_r_info
 #undef ELF_ST_BIND
+#undef fn_ELF_R_SYM
+#undef fn_ELF_R_INFO
 #undef uint_t
 #undef _w
 #undef _align

@@ -52,8 +56,12 @@
 # define Elf_Rela		Elf64_Rela
 # define Elf_Sym		Elf64_Sym
 # define ELF_R_SYM		ELF64_R_SYM
+# define Elf_r_sym		Elf64_r_sym
 # define ELF_R_INFO		ELF64_R_INFO
+# define Elf_r_info		Elf64_r_info
 # define ELF_ST_BIND		ELF64_ST_BIND
+# define fn_ELF_R_SYM		fn_ELF64_R_SYM
+# define fn_ELF_R_INFO		fn_ELF64_R_INFO
 # define uint_t			uint64_t
 # define _w			w8
 # define _align			7u

@@ -72,14 +80,32 @@
 # define Elf_Rela		Elf32_Rela
 # define Elf_Sym		Elf32_Sym
 # define ELF_R_SYM		ELF32_R_SYM
+# define Elf_r_sym		Elf32_r_sym
 # define ELF_R_INFO		ELF32_R_INFO
+# define Elf_r_info		Elf32_r_info
 # define ELF_ST_BIND		ELF32_ST_BIND
+# define fn_ELF_R_SYM		fn_ELF32_R_SYM
+# define fn_ELF_R_INFO		fn_ELF32_R_INFO
 # define uint_t			uint32_t
 # define _w			w
 # define _align			3u
 # define _size			4
 #endif
 
+/* Functions and pointers that 64-bit EM_MIPS can override. */
+static uint_t fn_ELF_R_SYM(Elf_Rel const *rp)
+{
+	return ELF_R_SYM(_w(rp->r_info));
+}
+static uint_t (*Elf_r_sym)(Elf_Rel const *rp) = fn_ELF_R_SYM;
+
+static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
+{
+	rp->r_info = ELF_R_INFO(sym, type);
+}
+static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
+
+
 /* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
 static void append_func(Elf_Ehdr *const ehdr,
 			Elf_Shdr *const shstr,

@@ -197,22 +223,22 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
 	for (t = nrel; t; --t) {
 		if (!mcountsym) {
 			Elf_Sym const *const symp =
-				&sym0[ELF_R_SYM(_w(relp->r_info))];
+				&sym0[Elf_r_sym(relp)];
 			char const *symname = &str0[w(symp->st_name)];
 
 			if ('.' == symname[0])
 				++symname;  /* ppc64 hack */
 			if (0 == strcmp((('_' == gpfx) ? "_mcount" : "mcount"),
 					symname))
-				mcountsym = ELF_R_SYM(_w(relp->r_info));
+				mcountsym = Elf_r_sym(relp);
 		}
 
-		if (mcountsym == ELF_R_SYM(_w(relp->r_info))) {
+		if (mcountsym == Elf_r_sym(relp)) {
 			uint_t const addend = _w(_w(relp->r_offset) - recval);
 
 			mrelp->r_offset = _w(offbase
 				+ ((void *)mlocp - (void *)mloc0));
-			mrelp->r_info = _w(ELF_R_INFO(recsym, reltype));
+			Elf_r_info(mrelp, recsym, reltype);
 			if (sizeof(Elf_Rela) == rel_entsize) {
 				((Elf_Rela *)mrelp)->r_addend = addend;
 				*mlocp++ = 0;

Quoted 1 line · Wu Zhangjin

From: Wu Zhangjin <[email protected]>

The From above states that you wrote this. Did you modify what John and Maciej did? If so, please state clearly what each author has done, and how you modified it. If you did not write this, please change the From to the correct author.

If you did modify it, then state something like this in the change log.

Original version written by John Reiser <[email protected]>

Usage of "union mips_r_info" and the functions MIPS64_r_sym() and MIPS64_r_info() written by Maciej W. Rozycki <[email protected]>

Then state the changes you made.

Quoted 6 lines

MIPS64 has 'weird' Elf64_Rel.r_info[1,2], which must be used instead of the generic Elf64_Rel.r_info, otherwise, the C version of recordmcount will not work for "segmentation fault".

Quoted 7 lines

----
[1] http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
[2] arch/mips/include/asm/module.h

Signed-off-by John Reiser <[email protected]>

Signed-off-by Maciej W. Rozycki <[email protected]>

Tested-by Wu Zhangjin <[email protected]>

Again, if you made changes, you need a SoB yourself.

Thanks!

-- Steve

Quoted 168 lines

---
 scripts/recordmcount.c |   41 +++++++++++++++++++++++++++++++++++++++++ scripts/recordmcount.h |   34 ++++++++++++++++++++++++++++++----

 2 files changed, 71 insertions(+), 4 deletions(-)

scripts/recordmcount.c +33 -0

index 26e1271..2d32b9c 100644
@@ -217,6 +217,39 @@ is_mcounted_section_name(char const *const txtname)
  #define RECORD_MCOUNT_64
  #include "recordmcount.h"
 
+/* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
+ * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
+ * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
+ * to imply the order of the members; the spec does not say so.
+ *   typedef unsigned char Elf64_Byte;
+ * fails on MIPS64 because their <elf.h> already has it!
+ */
+
+typedef uint8_t myElf64_Byte;                /* Type for a 8-bit quantity.  */
+
+union mips_r_info {
+     Elf64_Xword r_info;
+     struct {
+             Elf64_Word r_sym;               /* Symbol index.  */
+             myElf64_Byte r_ssym;            /* Special symbol.  */
+             myElf64_Byte r_type3;           /* Third relocation.  */
+             myElf64_Byte r_type2;           /* Second relocation.  */
+             myElf64_Byte r_type;            /* First relocation.  */
+     } r_mips;
+};
+
+static uint64_t MIPS64_r_sym(Elf64_Rel const *rp)
+{
+     return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym);
+}
+
+static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
+{
+     rp->r_info = ((union mips_r_info){
+             .r_mips = { .r_sym = w(sym), .r_type = type }
+     }).r_info;
+}
+

 static void
 do_file(char const *const fname)
 {

scripts/recordmcount.c +8 -0

@@ -268,6 +301,7 @@ do_file(char const *const fname)
       case EM_386:     reltype = R_386_32;                   break;
       case EM_ARM:     reltype = R_ARM_ABS32;                break;
       case EM_IA_64:   reltype = R_IA64_IMM64;   gpfx = '_'; break;
+     case EM_MIPS:    /* reltype: e_class    */ gpfx = '_'; break;
       case EM_PPC:     reltype = R_PPC_ADDR32;   gpfx = '_'; break;
       case EM_PPC64:   reltype = R_PPC64_ADDR64; gpfx = '_'; break;
       case EM_S390:    /* reltype: e_class    */ gpfx = '_'; break;

@@ -291,6 +325,8 @@ do_file(char const *const fname)
               }
               if (EM_S390 == w2(ehdr->e_machine))
                       reltype = R_390_32;
+             if (EM_MIPS == w2(ehdr->e_machine))
+                     reltype = R_MIPS_32;
               do32(ehdr, fname, reltype);
       } break;
       case ELFCLASS64: {

@@ -303,6 +339,11 @@ do_file(char const *const fname)
               }
               if (EM_S390 == w2(ghdr->e_machine))
                       reltype = R_390_64;
+             if (EM_MIPS == w2(ghdr->e_machine)) {
+                     reltype = R_MIPS_64;
+                     Elf64_r_sym = MIPS64_r_sym;
+                     Elf64_r_info = MIPS64_r_info;
+             }
               do64(ghdr, fname, reltype);
       } break;
       }  /* end switch */

scripts/recordmcount.h +26 -0

index 7f39d09..190fd18 100644
@@ -31,8 +31,12 @@
  #undef Elf_Rela
  #undef Elf_Sym
  #undef ELF_R_SYM
+#undef Elf_r_sym
  #undef ELF_R_INFO
+#undef Elf_r_info
  #undef ELF_ST_BIND
+#undef fn_ELF_R_SYM
+#undef fn_ELF_R_INFO
  #undef uint_t
  #undef _w
  #undef _align

@@ -52,8 +56,12 @@
  # define Elf_Rela            Elf64_Rela
  # define Elf_Sym             Elf64_Sym
  # define ELF_R_SYM           ELF64_R_SYM
+# define Elf_r_sym           Elf64_r_sym
  # define ELF_R_INFO          ELF64_R_INFO
+# define Elf_r_info          Elf64_r_info
  # define ELF_ST_BIND         ELF64_ST_BIND
+# define fn_ELF_R_SYM                fn_ELF64_R_SYM
+# define fn_ELF_R_INFO               fn_ELF64_R_INFO
  # define uint_t                      uint64_t
  # define _w                  w8
  # define _align                      7u

@@ -72,14 +80,32 @@
  # define Elf_Rela            Elf32_Rela
  # define Elf_Sym             Elf32_Sym
  # define ELF_R_SYM           ELF32_R_SYM
+# define Elf_r_sym           Elf32_r_sym
  # define ELF_R_INFO          ELF32_R_INFO
+# define Elf_r_info          Elf32_r_info
  # define ELF_ST_BIND         ELF32_ST_BIND
+# define fn_ELF_R_SYM                fn_ELF32_R_SYM
+# define fn_ELF_R_INFO               fn_ELF32_R_INFO
  # define uint_t                      uint32_t
  # define _w                  w
  # define _align                      3u
  # define _size                       4
  #endif
 
+/* Functions and pointers that 64-bit EM_MIPS can override. */
+static uint_t fn_ELF_R_SYM(Elf_Rel const *rp)
+{
+     return ELF_R_SYM(_w(rp->r_info));
+}
+static uint_t (*Elf_r_sym)(Elf_Rel const *rp) = fn_ELF_R_SYM;
+
+static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
+{
+     rp->r_info = ELF_R_INFO(sym, type);
+}
+static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
+
+
  /* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
  static void append_func(Elf_Ehdr *const ehdr,
                       Elf_Shdr *const shstr,

@@ -197,22 +223,22 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
       for (t = nrel; t; --t) {
               if (!mcountsym) {

                      Elf_Sym const *const symp =
-                             &sym0[ELF_R_SYM(_w(relp->r_info))];
+                             &sym0[Elf_r_sym(relp)]; char const *symname = &str0[w(symp->st_name)];

                      if ('.' == symname[0])
                              ++symname;  /* ppc64 hack */
                      if (0 == strcmp((('_' == gpfx) ? "_mcount" : "mcount"), symname))
-                             mcountsym = ELF_R_SYM(_w(relp->r_info));
+                             mcountsym = Elf_r_sym(relp);
              }

-             if (mcountsym == ELF_R_SYM(_w(relp->r_info))) {
+             if (mcountsym == Elf_r_sym(relp)) {
                      uint_t const addend = _w(_w(relp->r_offset) - recval);

                      mrelp->r_offset = _w(offbase
                              + ((void *)mlocp - (void *)mloc0));
-                     mrelp->r_info = _w(ELF_R_INFO(recsym, reltype));
+                     Elf_r_info(mrelp, recsym, reltype); if (sizeof(Elf_Rela) == rel_entsize) { ((Elf_Rela *)mrelp)->r_addend = addend; *mlocp++ = 0;

Quoted 8 lines · Steven Rostedt

Quoted 1 line · Wu Zhangjin

From: Wu Zhangjin <[email protected]>

The From above states that you wrote this. Did you modify what John and Maciej did? If so, please state clearly what each author has done, and how you modified it. If you did not write this, please change the From to the correct author.

Quoted 7 lines

If you did modify it, then state something like this in the change log.

Original version written by John Reiser <[email protected]>

Usage of "union mips_r_info" and the functions MIPS64_r_sym() and MIPS64_r_info() written by Maciej W. Rozycki <[email protected]>

yeah, that is true above.

Quoted 1 line

Then state the changes you made.

I didn't change it, just added the comments in the patch log and tested it.

Should I resend the patch with the change log information about John and Maciej?

Quoted 19 lines · wu zhangjin

Quoted 8 lines · Steven Rostedt

Quoted 1 line · Wu Zhangjin

From: Wu Zhangjin <[email protected]>

The From above states that you wrote this. Did you modify what John and Maciej did? If so, please state clearly what each author has done, and how you modified it. If you did not write this, please change the From to the correct author.

Quoted 7 lines

If you did modify it, then state something like this in the change log.

Original version written by John Reiser <[email protected]>

Usage of "union mips_r_info" and the functions MIPS64_r_sym() and MIPS64_r_info() written by Maciej W. Rozycki <[email protected]>

yeah, that is true above.

Quoted 6 lines

Quoted 1 line

Then state the changes you made.

I didn't change it, just added the comments in the patch log and tested it.

Should I resend the patch with the change log information about John and Maciej?

I can make the changes.

Then the patch is originally John's, right?

I'll make him the author, with the comment about Maciej, and keep you as the Tested-by.

From: Wu Zhangjin <[email protected]>

Selects HAVE_C_RECORDMCOUNT to use the C version of the recordmcount intead of the old Perl Version of recordmcount.

Signed-off-by Wu Zhangjin <[email protected]>

---
 arch/mips/Kconfig |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

arch/mips/Kconfig +1 -0

index 46cae2b..144e4b3 100644
@@ -9,6 +9,7 @@ config MIPS
 	select HAVE_FUNCTION_TRACE_MCOUNT_TEST
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_FTRACE_MCOUNT_RECORD
+	select HAVE_C_RECORDMCOUNT
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES

Quoted 6 lines · Wu Zhangjin

From: Wu Zhangjin <[email protected]>

Selects HAVE_C_RECORDMCOUNT to use the C version of the recordmcount intead of the old Perl Version of recordmcount.

Signed-off-by Wu Zhangjin <[email protected]>

I'd like to get an Acked-by from Ralf and Maciej on this.