Re: [PATCH 1/2] binfmt_elf_fdpic: support 64-bit systems

[Palmer Dabbelt <palmer@dabbelt.com>]

On Thu, 20 Apr 2023 07:58:29 PDT (-0700), gerg@kernel.org wrote:
> Hi Palmer,
>
> On 19/4/23 13:27, Palmer Dabbelt wrote:
>> On Wed, 29 Mar 2023 06:48:55 PDT (-0700), gerg@kernel.org wrote:
>>>
>>> On 22/3/23 08:49, Palmer Dabbelt wrote:
>>>> On Tue, 28 Feb 2023 05:51:25 PST (-0800), gerg@kernel.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@kernel.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@rivosinc.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.
>>>
>>> Just following up. I haven't seen any feedback on this - did I miss any?
>>
>> If you did then I did too.  I'm not really sure what to do here: it looks fine to me, but it's not really my area so I'd prefer to have someone who understands this stuff a bit better chime in.
>>
>> It looks like some Arm patches recently went in through that tree, though, so maybe that's how things are supposed to go here?
>
> There doesn't seem to be anyone who is clearly the designated maintainer
> for binfmt_elf_fdpic, or even just sheparding fixes for it. It mostly seems
> to be tree-wide changes and cleanups that are getting done to it.
>
> So I have no idea... I have at least one fix inside binfmt_elf_fdpic.c for
> ARM architecture that I am preparing now too, not sure how that is going to
> go either.

Looks like maybe nobody is taking these, then?  Certainly nobody has 
chimed in.  There's been some minor conflicts over the past few months, 
do you mind sending a v2?  If nobody says anything on that I'll just 
take it via the RISC-V tree.

>
> Regards
> Greg
>
>
>
>>>>> 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 */
>>>>