Add support for enabling and using the binfmt_elf_fdpic program loader
on RISC-V platforms. The most important change is to setup registers
during program load to pass the mapping addresses to the new process.
One of the interesting features of the elf-fdpic loader is that it
also allows appropriately compiled ELF format binaries to be loaded on
nommu systems. Appropriate being those compiled with -pie.
Signed-off-by: Greg Ungerer <gerg@xxxxxxxxxx>
---
v1->v2: rebase onto linux-6.5-rc1
increment PTRACE_GETFDPIC value to keep it unique
arch/riscv/include/asm/elf.h | 11 ++++++++++-
arch/riscv/include/asm/mmu.h | 4 ++++
arch/riscv/include/uapi/asm/ptrace.h | 5 +++++
fs/Kconfig.binfmt | 2 +-
4 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h
index c24280774caf..c33fe923ef6d 100644
--- a/arch/riscv/include/asm/elf.h
+++ b/arch/riscv/include/asm/elf.h
@@ -41,6 +41,7 @@ extern bool compat_elf_check_arch(Elf32_Ehdr *hdr);
#define compat_elf_check_arch compat_elf_check_arch
#define CORE_DUMP_USE_REGSET
+#define ELF_FDPIC_CORE_EFLAGS 0
#define ELF_EXEC_PAGESIZE (PAGE_SIZE)
/*
@@ -69,6 +70,13 @@ extern bool compat_elf_check_arch(Elf32_Ehdr *hdr);
#define ELF_HWCAP riscv_get_elf_hwcap()
extern unsigned long elf_hwcap;
+#define ELF_FDPIC_PLAT_INIT(_r, _exec_map_addr, _interp_map_addr, dynamic_addr) \
+ do { \
+ (_r)->a1 = _exec_map_addr; \
+ (_r)->a2 = _interp_map_addr; \
+ (_r)->a3 = dynamic_addr; \
+ } while (0)
+
/*
* This yields a string that ld.so will use to load implementation
* specific libraries for optimization. This is more specific in
@@ -78,7 +86,6 @@ extern unsigned long elf_hwcap;
#define COMPAT_ELF_PLATFORM (NULL)
-#ifdef CONFIG_MMU
#define ARCH_DLINFO \
do { \
/* \
@@ -115,6 +122,8 @@ do { \
else \
NEW_AUX_ENT(AT_IGNORE, 0); \
} while (0)
+
+#ifdef CONFIG_MMU
#define ARCH_HAS_SETUP_ADDITIONAL_PAGES
struct linux_binprm;
extern int arch_setup_additional_pages(struct linux_binprm *bprm,
diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
index 0099dc116168..355504b37f8e 100644
--- a/arch/riscv/include/asm/mmu.h
+++ b/arch/riscv/include/asm/mmu.h
@@ -20,6 +20,10 @@ typedef struct {
/* A local icache flush is needed before user execution can resume. */
cpumask_t icache_stale_mask;
#endif
+#ifdef CONFIG_BINFMT_ELF_FDPIC
+ unsigned long exec_fdpic_loadmap;
+ unsigned long interp_fdpic_loadmap;
+#endif
} mm_context_t;
void __init create_pgd_mapping(pgd_t *pgdp, uintptr_t va, phys_addr_t pa,
diff --git a/arch/riscv/include/uapi/asm/ptrace.h b/arch/riscv/include/uapi/asm/ptrace.h
index e17c550986a6..30f6d6537adc 100644
--- a/arch/riscv/include/uapi/asm/ptrace.h
+++ b/arch/riscv/include/uapi/asm/ptrace.h
@@ -10,6 +10,11 @@
#include <linux/types.h>
+#define PTRACE_GETFDPIC 33
+
+#define PTRACE_GETFDPIC_EXEC 0
+#define PTRACE_GETFDPIC_INTERP 1
+
/*
* User-mode register state for core dumps, ptrace, sigcontext
*
diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index 93539aac0e5b..f5693164ca9a 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -58,7 +58,7 @@ config ARCH_USE_GNU_PROPERTY
config BINFMT_ELF_FDPIC
bool "Kernel support for FDPIC ELF binaries"
default y if !BINFMT_ELF
- depends on ARM || ((M68K || SUPERH || XTENSA) && !MMU)
+ depends on ARM || ((M68K || RISCV || SUPERH || XTENSA) && !MMU)
select ELFCORE
help
ELF FDPIC binaries are based on ELF, but allow the individual load
--
2.25.1
