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Message-ID: <mhng-fec49316-5da9-4cab-af79-6115f13668c1@palmer-ri-x1c9a>
Date: Tue, 21 Mar 2023 15:49:40 -0700 (PDT)
From: Palmer Dabbelt <palmer@...belt.com>
To: gerg@...nel.org, viro@...iv.linux.org.uk, brauner@...nel.org,
ebiederm@...ssion.com, keescook@...omium.org
CC: linux-riscv@...ts.infradead.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, gerg@...nel.org
Subject: Re: [PATCH 1/2] binfmt_elf_fdpic: support 64-bit systems
On Tue, 28 Feb 2023 05:51:25 PST (-0800), gerg@...nel.org wrote:
> The binfmt_flat_fdpic code has a number of 32-bit specific data
> structures associated with it. Extend it to be able to support and
> be used on 64-bit systems as well.
>
> The new code defines a number of key 64-bit variants of the core
> elf-fdpic data structures - along side the existing 32-bit sized ones.
> A common set of generic named structures are defined to be either
> the 32-bit or 64-bit ones as required at compile time. This is a
> similar technique to that used in the ELF binfmt loader.
>
> For example:
>
> elf_fdpic_loadseg is either elf32_fdpic_loadseg or elf64_fdpic_loadseg
> elf_fdpic_loadmap is either elf32_fdpic_loadmap or elf64_fdpic_loadmap
>
> the choice based on ELFCLASS32 or ELFCLASS64.
>
> Signed-off-by: Greg Ungerer <gerg@...nel.org>
> ---
> fs/binfmt_elf_fdpic.c | 38 +++++++++++++++++-----------------
> include/linux/elf-fdpic.h | 14 ++++++++++++-
> include/uapi/linux/elf-fdpic.h | 15 ++++++++++++++
> 3 files changed, 47 insertions(+), 20 deletions(-)
Adding some of the binfmt/fs folks, who weren't directly on the mail.
It's looking like we're generally OK with this in RISC-V land, though
there's still no userspace posted. I don't think there's any rush here
and it might be prudent to wait for userspace to start going through a
bit of a review, but figured I'd at least poke everyone to see if
there's any thoughts.
I'm fine either way, so
Acked-by: Palmer Dabbelt <palmer@...osinc.com>
if that helps any. Also happy to take this through the RISC-V tree
along with the other if that's easier, but again no rush.
>
> diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
> index a05eafcacfb27..2eea6dd429fd6 100644
> --- a/fs/binfmt_elf_fdpic.c
> +++ b/fs/binfmt_elf_fdpic.c
> @@ -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;
> @@ -740,12 +740,12 @@ 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;
> #endif
> - struct elf32_fdpic_loadseg *seg;
> - struct elf32_phdr *phdr;
> + struct elf_fdpic_loadseg *seg;
> + struct elf_phdr *phdr;
> unsigned long load_addr, stop;
> unsigned nloads, tmp;
> size_t size;
> @@ -767,7 +767,7 @@ 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;
>
> load_addr = params->load_addr;
> @@ -843,8 +843,8 @@ 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) +
> @@ -854,11 +854,11 @@ 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;
> @@ -927,8 +927,8 @@ 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;
>
> @@ -1011,8 +1011,8 @@ 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;
>
> diff --git a/include/linux/elf-fdpic.h b/include/linux/elf-fdpic.h
> index 3bea95a1af537..e533f45131945 100644
> --- a/include/linux/elf-fdpic.h
> +++ b/include/linux/elf-fdpic.h
> @@ -10,13 +10,25 @@
>
> #include <uapi/linux/elf-fdpic.h>
>
> +#if ELF_CLASS == ELFCLASS32
> +#define Elf_Sword Elf32_Sword
> +#define elf_fdpic_loadseg elf32_fdpic_loadseg
> +#define elf_fdpic_loadmap elf32_fdpic_loadmap
> +#define ELF_FDPIC_LOADMAP_VERSION ELF32_FDPIC_LOADMAP_VERSION
> +#else
> +#define Elf_Sword Elf64_Sxword
> +#define elf_fdpic_loadmap elf64_fdpic_loadmap
> +#define elf_fdpic_loadseg elf64_fdpic_loadseg
> +#define ELF_FDPIC_LOADMAP_VERSION ELF64_FDPIC_LOADMAP_VERSION
> +#endif
> +
> /*
> * binfmt binary parameters structure
> */
> struct elf_fdpic_params {
> struct elfhdr hdr; /* ref copy of ELF header */
> struct elf_phdr *phdrs; /* ref copy of PT_PHDR table */
> - struct elf32_fdpic_loadmap *loadmap; /* loadmap to be passed to userspace */
> + struct elf_fdpic_loadmap *loadmap; /* loadmap to be passed to userspace */
> unsigned long elfhdr_addr; /* mapped ELF header user address */
> unsigned long ph_addr; /* mapped PT_PHDR user address */
> unsigned long map_addr; /* mapped loadmap user address */
> diff --git a/include/uapi/linux/elf-fdpic.h b/include/uapi/linux/elf-fdpic.h
> index 4fcc6cfebe185..ec23f08711292 100644
> --- a/include/uapi/linux/elf-fdpic.h
> +++ b/include/uapi/linux/elf-fdpic.h
> @@ -32,4 +32,19 @@ struct elf32_fdpic_loadmap {
>
> #define ELF32_FDPIC_LOADMAP_VERSION 0x0000
>
> +/* segment mappings for ELF FDPIC libraries/executables/interpreters */
> +struct elf64_fdpic_loadseg {
> + Elf64_Addr addr; /* core address to which mapped */
> + Elf64_Addr p_vaddr; /* VMA recorded in file */
> + Elf64_Word p_memsz; /* allocation size recorded in file */
> +};
> +
> +struct elf64_fdpic_loadmap {
> + Elf64_Half version; /* version of these structures, just in case... */
> + Elf64_Half nsegs; /* number of segments */
> + struct elf64_fdpic_loadseg segs[];
> +};
> +
> +#define ELF64_FDPIC_LOADMAP_VERSION 0x0000
> +
> #endif /* _UAPI_LINUX_ELF_FDPIC_H */
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