Unverified Commit 9549fb35 authored by Greg Ungerer's avatar Greg Ungerer Committed by Palmer Dabbelt
Browse files

riscv: support the elf-fdpic binfmt loader 



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: default avatarGreg Ungerer <gerg@kernel.org>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230711130754.481209-3-gerg@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent b922bf04

arch/riscv/include/asm/elf.h

+10 −1
Original line number Diff line number Diff line
@@ -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,

arch/riscv/include/asm/mmu.h

+4 −0
Original line number Diff line number Diff line
@@ -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,

arch/riscv/include/uapi/asm/ptrace.h

+5 −0
Original line number Diff line number Diff line
@@ -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

 *

fs/Kconfig.binfmt

+1 −1
Original line number Diff line number Diff line
@@ -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