[PATCH v2 5/8] ARM: add ELF_FDPIC support

[Nicolas Pitre]

This includes the necessary code to recognise the FDPIC format on ARM
and the ptrace command definitions used by the common ptrace code.

Based on patches originally from Mickael Guene <mickael.guene at st.com>.

Signed-off-by: Nicolas Pitre <nico at linaro.org>
---
 arch/arm/include/asm/elf.h         | 12 ++++++++++++
 arch/arm/include/asm/mmu.h         |  4 ++++
 arch/arm/include/uapi/asm/ptrace.h |  4 ++++
 fs/Kconfig.binfmt                  |  2 +-
 4 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/elf.h b/arch/arm/include/asm/elf.h
index e2786acf82..ad0ca4f2ba 100644
--- a/arch/arm/include/asm/elf.h
+++ b/arch/arm/include/asm/elf.h
@@ -100,6 +100,11 @@ struct elf32_hdr;
 extern int elf_check_arch(const struct elf32_hdr *);
 #define elf_check_arch elf_check_arch
 
+#define ELFOSABI_ARM_FDPIC  65	/* ARM FDPIC platform */
+#define elf_check_fdpic(x)  ((x)->e_ident[EI_OSABI] == ELFOSABI_ARM_FDPIC)
+#define elf_check_const_displacement(x)  ((x)->e_flags & EF_ARM_PIC)
+#define ELF_FDPIC_CORE_EFLAGS  0
+
 #define vmcore_elf64_check_arch(x) (0)
 
 extern int arm_elf_read_implies_exec(int);
@@ -120,6 +125,13 @@ int dump_task_regs(struct task_struct *t, elf_gregset_t *elfregs);
    have no such handler.  */
 #define ELF_PLAT_INIT(_r, load_addr)	(_r)->ARM_r0 = 0
 
+#define ELF_FDPIC_PLAT_INIT(_r, _exec_map_addr, _interp_map_addr, dynamic_addr) \
+	do { \
+		(_r)->ARM_r7 = _exec_map_addr; \
+		(_r)->ARM_r8 = _interp_map_addr; \
+		(_r)->ARM_r9 = dynamic_addr; \
+	} while(0)
+
 extern void elf_set_personality(const struct elf32_hdr *);
 #define SET_PERSONALITY(ex)	elf_set_personality(&(ex))
 
diff --git a/arch/arm/include/asm/mmu.h b/arch/arm/include/asm/mmu.h
index a5b4742105..e0eb16680a 100644
--- a/arch/arm/include/asm/mmu.h
+++ b/arch/arm/include/asm/mmu.h
@@ -33,6 +33,10 @@ typedef struct {
  */
 typedef struct {
 	unsigned long	end_brk;
+#ifdef CONFIG_BINFMT_ELF_FDPIC
+	unsigned long	exec_fdpic_loadmap;
+	unsigned long	interp_fdpic_loadmap;
+#endif
 } mm_context_t;
 
 #endif
diff --git a/arch/arm/include/uapi/asm/ptrace.h b/arch/arm/include/uapi/asm/ptrace.h
index 5af0ed1b82..3173eb9751 100644
--- a/arch/arm/include/uapi/asm/ptrace.h
+++ b/arch/arm/include/uapi/asm/ptrace.h
@@ -31,6 +31,10 @@
 #define PTRACE_SETVFPREGS	28
 #define PTRACE_GETHBPREGS	29
 #define PTRACE_SETHBPREGS	30
+#define PTRACE_GETFDPIC		31
+
+#define PTRACE_GETFDPIC_EXEC	0
+#define PTRACE_GETFDPIC_INTERP	1
 
 /*
  * PSR bits
diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index b2f82cf6bf..6ef70ce8e9 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -35,7 +35,7 @@ config ARCH_BINFMT_ELF_STATE
 config BINFMT_ELF_FDPIC
 	bool "Kernel support for FDPIC ELF binaries"
 	default y
-	depends on (FRV || BLACKFIN || (SUPERH32 && !MMU) || C6X)
+	depends on ((ARM && !MMU) || FRV || BLACKFIN || (SUPERH32 && !MMU) || C6X)
 	select ELFCORE
 	help
 	  ELF FDPIC binaries are based on ELF, but allow the individual load
-- 
2.9.5