Unverified Commit 150e3c92 authored by Palmer Dabbelt's avatar Palmer Dabbelt
Browse files

Merge patch series "riscv: support ELF format binaries in nommu mode" 

Greg Ungerer <gerg@kernel.org> says:

The following changes add the ability to run ELF format binaries when
running RISC-V in nommu mode. That support is actually part of the
ELF-FDPIC loader, so these changes are all about making that work on
RISC-V.

The first issue to deal with is making the ELF-FDPIC loader capable of
handling 64-bit ELF files. As coded right now it only supports 32-bit
ELF files.

Secondly some changes are required to enable and compile the ELF-FDPIC
loader on RISC-V and to pass the ELF-FDPIC mapping addresses through to
user space when execing the new program.

These changes have not been used to run actual ELF-FDPIC binaries.
It is used to load and run normal ELF - compiled -pie format. Though the
underlying changes are expected to work with full ELF-FDPIC binaries if
or when that is supported on RISC-V in gcc.

To avoid needing changes to the C-library (tested with uClibc-ng
currently) there is a simple runtime dynamic loader (interpreter)
available to do the final relocations, https://github.com/gregungerer/uldso.
The nice thing about doing it this way is that the same program
binary can also be loaded with the usual ELF loader in MMU linux.

The motivation here is to provide an easy to use alternative to the
flat format binaries normally used for RISC-V nommu based systems.

* b4-shazam-merge:
  riscv: support the elf-fdpic binfmt loader
  binfmt_elf_fdpic: support 64-bit systems

Link: https://lore.kernel.org/r/20230711130754.481209-1-gerg@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parents 7f7d3ea6 9549fb35

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

fs/binfmt_elf_fdpic.c

+19 −19
Original line number Diff line number Diff line
@@ -138,7 +138,7 @@ static int is_constdisp(struct elfhdr *hdr) 
static int elf_fdpic_fetch_phdrs(struct elf_fdpic_params *params,

				 struct file *file)

{

	struct elf32_phdr *phdr;

	struct elf_phdr *phdr;

	unsigned long size;

	int retval, loop;

	loff_t pos = params->hdr.e_phoff;
@@ -560,8 +560,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm, 
	sp &= ~7UL;



	/* stack the load map(s) */

	len = sizeof(struct elf32_fdpic_loadmap);

	len += sizeof(struct elf32_fdpic_loadseg) * exec_params->loadmap->nsegs;

	len = sizeof(struct elf_fdpic_loadmap);

	len += sizeof(struct elf_fdpic_loadseg) * exec_params->loadmap->nsegs;

	sp = (sp - len) & ~7UL;

	exec_params->map_addr = sp;
@@ -571,8 +571,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm, 
	current->mm->context.exec_fdpic_loadmap = (unsigned long) sp;



	if (interp_params->loadmap) {

		len = sizeof(struct elf32_fdpic_loadmap);

		len += sizeof(struct elf32_fdpic_loadseg) *

		len = sizeof(struct elf_fdpic_loadmap);

		len += sizeof(struct elf_fdpic_loadseg) *

			interp_params->loadmap->nsegs;

		sp = (sp - len) & ~7UL;

		interp_params->map_addr = sp;
@@ -740,13 +740,13 @@ static int elf_fdpic_map_file(struct elf_fdpic_params *params, 
			      struct mm_struct *mm,

			      const char *what)

{

	struct elf32_fdpic_loadmap *loadmap;

	struct elf_fdpic_loadmap *loadmap;

#ifdef CONFIG_MMU

	struct elf32_fdpic_loadseg *mseg;

	struct elf_fdpic_loadseg *mseg;

	unsigned long load_addr;

#endif

	struct elf32_fdpic_loadseg *seg;

	struct elf32_phdr *phdr;

	struct elf_fdpic_loadseg *seg;

	struct elf_phdr *phdr;

	unsigned nloads, tmp;

	unsigned long stop;

	int loop, ret;
@@ -766,7 +766,7 @@ static int elf_fdpic_map_file(struct elf_fdpic_params *params, 


	params->loadmap = loadmap;



	loadmap->version = ELF32_FDPIC_LOADMAP_VERSION;

	loadmap->version = ELF_FDPIC_LOADMAP_VERSION;

	loadmap->nsegs = nloads;



	/* map the requested LOADs into the memory space */
@@ -839,8 +839,8 @@ static int elf_fdpic_map_file(struct elf_fdpic_params *params, 
			if (phdr->p_vaddr >= seg->p_vaddr &&

			    phdr->p_vaddr + phdr->p_memsz <=

			    seg->p_vaddr + seg->p_memsz) {

				Elf32_Dyn __user *dyn;

				Elf32_Sword d_tag;

				Elf_Dyn __user *dyn;

				Elf_Sword d_tag;



				params->dynamic_addr =

					(phdr->p_vaddr - seg->p_vaddr) +
@@ -850,11 +850,11 @@ static int elf_fdpic_map_file(struct elf_fdpic_params *params, 
				 * one item, and that the last item is a NULL

				 * entry */

				if (phdr->p_memsz == 0 ||

				    phdr->p_memsz % sizeof(Elf32_Dyn) != 0)

				    phdr->p_memsz % sizeof(Elf_Dyn) != 0)

					goto dynamic_error;



				tmp = phdr->p_memsz / sizeof(Elf32_Dyn);

				dyn = (Elf32_Dyn __user *)params->dynamic_addr;

				tmp = phdr->p_memsz / sizeof(Elf_Dyn);

				dyn = (Elf_Dyn __user *)params->dynamic_addr;

				if (get_user(d_tag, &dyn[tmp - 1].d_tag) ||

				    d_tag != 0)

					goto dynamic_error;
@@ -923,8 +923,8 @@ static int elf_fdpic_map_file_constdisp_on_uclinux( 
	struct file *file,

	struct mm_struct *mm)

{

	struct elf32_fdpic_loadseg *seg;

	struct elf32_phdr *phdr;

	struct elf_fdpic_loadseg *seg;

	struct elf_phdr *phdr;

	unsigned long load_addr, base = ULONG_MAX, top = 0, maddr = 0;

	int loop, ret;
@@ -1007,8 +1007,8 @@ static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params, 
					     struct file *file,

					     struct mm_struct *mm)

{

	struct elf32_fdpic_loadseg *seg;

	struct elf32_phdr *phdr;

	struct elf_fdpic_loadseg *seg;

	struct elf_phdr *phdr;

	unsigned long load_addr, delta_vaddr;

	int loop, dvset;