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Message-ID: <mhng-10a90bed-b62d-4e5a-8295-e6b512a350d2@palmer-ri-x1c9a>
Date: Mon, 10 Jul 2023 16:18:25 -0700 (PDT)
From: Palmer Dabbelt <palmer@...belt.com>
To: gerg@...nel.org
CC: viro@...iv.linux.org.uk, brauner@...nel.org, ebiederm@...ssion.com,
keescook@...omium.org, linux-riscv@...ts.infradead.org,
linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] binfmt_elf_fdpic: support 64-bit systems
On Thu, 20 Apr 2023 07:58:29 PDT (-0700), gerg@...nel.org wrote:
> Hi Palmer,
>
> On 19/4/23 13:27, Palmer Dabbelt wrote:
>> On Wed, 29 Mar 2023 06:48:55 PDT (-0700), gerg@...nel.org wrote:
>>>
>>> On 22/3/23 08:49, Palmer Dabbelt wrote:
>>>> 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.
>>>
>>> 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 */
>>>>
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