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Date: Wed, 27 Oct 2010 18:59:07 +0800
From: Wu Zhangjin <wuzhangjin@...il.com>
To: rostedt@...dmis.org, Ralf Baechle <ralf@...ux-mips.org>,
linux-mips@...ux-mips.org, linux-kernel@...r.kernel.org
Cc: John Reiser <jreiser@...wagon.com>,
"Maciej W. Rozycki" <macro@...ux-mips.org>,
David Daney <ddaney@...iumnetworks.com>,
Wu Zhangjin <wuzhangjin@...il.com>,
John Reiser <jreiser@...Wagon.com>
Subject: [PATCH 1/3] ftrace/MIPS: Add MIPS64 support for C version of recordmcount
From: Wu Zhangjin <wuzhangjin@...il.com>
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 <jreiser@...Wagon.com>
Signed-off-by: Maciej W. Rozycki <macro@...ux-mips.org>
Tested-by: Wu Zhangjin <wuzhangjin@...il.com>
---
scripts/recordmcount.c | 41 +++++++++++++++++++++++++++++++++++++++++
scripts/recordmcount.h | 34 ++++++++++++++++++++++++++++++----
2 files changed, 71 insertions(+), 4 deletions(-)
diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index 26e1271..2d32b9c 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -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 */
diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index 7f39d09..190fd18 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -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;
--
1.7.1
--
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