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

[Greg Ungerer <gerg@kernel.org>]

Hi Palmer,

On 11/7/23 09:18, Palmer Dabbelt wrote:
> 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.

Yes, its been complete silence


>  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.

Sounds like a good plan.
I will send out a v2 today.

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 */
>>>>>

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