Re: [PATCH 16/23] arm64: ilp32: introduce binfmt_ilp32.c

["Zhangjian (Bamvor)" <bamvor.zhangjian@huawei.com>]

Hi, again

I found another issue in binfmt_ilp32.c. We are using the ELF_ET_DYN_BASE
for ilp32 application. The default ELF_ET_DYN_BASE is calculated by
TASK_SIZE_64. IIUC, we should define the following things in binfmt_ilp32.c
which is the same value as aarch32:

+#undef ELF_ET_DYN_BASE
+#define ELF_ET_DYN_BASE COMPAT_ELF_ET_DYN_BASE

Note that the ilp32 library works without this patch. After read code and
debug, the address is corrected in get_unmapped_area. I suspect find_vma
fix this wrong address.

Ideas?

Regards

Bamvor

On 2016/6/13 11:05, Zhangjian (Bamvor) wrote:
> Hi, Yury
>
> On 2016/5/24 8:04, Yury Norov wrote:
>> to handle ILP32 binaries
>>
>> Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
>> ---
>>   arch/arm64/kernel/Makefile       |  1 +
>>   arch/arm64/kernel/binfmt_ilp32.c | 91 ++++++++++++++++++++++++++++++++++++++++
>>   2 files changed, 92 insertions(+)
>>   create mode 100644 arch/arm64/kernel/binfmt_ilp32.c
>>
>> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
>> index 6bc9738..9dfdf86 100644
>> --- a/arch/arm64/kernel/Makefile
>> +++ b/arch/arm64/kernel/Makefile
>> @@ -28,6 +28,7 @@ $(obj)/%.stub.o: $(obj)/%.o FORCE
>>   arm64-obj-$(CONFIG_AARCH32_EL0)        += sys32.o kuser32.o signal32.o     \
>>                          sys_compat.o entry32.o        \
>>                          ../../arm/kernel/opcodes.o binfmt_elf32.o
>> +arm64-obj-$(CONFIG_ARM64_ILP32)        += binfmt_ilp32.o
>>   arm64-obj-$(CONFIG_FUNCTION_TRACER)    += ftrace.o entry-ftrace.o
>>   arm64-obj-$(CONFIG_MODULES)        += arm64ksyms.o module.o
>>   arm64-obj-$(CONFIG_ARM64_MODULE_PLTS)    += module-plts.o
>> diff --git a/arch/arm64/kernel/binfmt_ilp32.c b/arch/arm64/kernel/binfmt_ilp32.c
>> new file mode 100644
>> index 0000000..a934fd4
>> --- /dev/null
>> +++ b/arch/arm64/kernel/binfmt_ilp32.c
>> @@ -0,0 +1,91 @@
>> +/*
>> + * Support for ILP32 Linux/aarch64 ELF binaries.
>> + */
>> +
>> +#include <linux/elfcore-compat.h>
>> +#include <linux/time.h>
>> +
>> +#undef    ELF_CLASS
>> +#define ELF_CLASS    ELFCLASS32
>> +
>> +#undef    elfhdr
>> +#undef    elf_phdr
>> +#undef    elf_shdr
>> +#undef    elf_note
>> +#undef    elf_addr_t
>> +#define elfhdr        elf32_hdr
>> +#define elf_phdr    elf32_phdr
>> +#define elf_shdr    elf32_shdr
>> +#define elf_note    elf32_note
>> +#define elf_addr_t    Elf32_Addr
>> +
>> +/*
>> + * Some data types as stored in coredump.
>> + */
>> +#define user_long_t        compat_long_t
>> +#define user_siginfo_t        compat_siginfo_t
>> +#define copy_siginfo_to_user    copy_siginfo_to_user32
>> +
>> +/*
>> + * The machine-dependent core note format types are defined in elfcore-compat.h,
>> + * which requires asm/elf.h to define compat_elf_gregset_t et al.
>> + */
>> +#define elf_prstatus    compat_elf_prstatus
>> +#define elf_prpsinfo    compat_elf_prpsinfo
>> +
>> +/*
>> + * Compat version of cputime_to_compat_timeval, perhaps this
>> + * should be an inline in <linux/compat.h>.
>> + */
>> +static void cputime_to_compat_timeval(const cputime_t cputime,
>> +                      struct compat_timeval *value)
>> +{
>> +    struct timeval tv;
>> +    cputime_to_timeval(cputime, &tv);
>> +    value->tv_sec = tv.tv_sec;
>> +    value->tv_usec = tv.tv_usec;
>> +}
>> +
>> +#undef cputime_to_timeval
>> +#define cputime_to_timeval cputime_to_compat_timeval
>> +
>> +/* AARCH64 ILP32 EABI. */
>> +#undef elf_check_arch
>> +#define elf_check_arch(x)        (((x)->e_machine == EM_AARCH64)    \
>> +                    && (x)->e_ident[EI_CLASS] == ELFCLASS32)
>> +
>> +#undef SET_PERSONALITY
>> +#define SET_PERSONALITY(ex)                        \
>> +do {                                    \
>> +    set_thread_flag(TIF_32BIT_AARCH64);                \
>> +    clear_thread_flag(TIF_32BIT);                    \
>> +} while (0)
>> +
>> +#undef ARCH_DLINFO
>> +#define ARCH_DLINFO                            \
>> +do {                                    \
>> +    NEW_AUX_ENT(AT_SYSINFO_EHDR,                    \
>> +            (elf_addr_t)(long)current->mm->context.vdso);    \
>> +} while (0)
>> +
>> +#ifdef __AARCH64EB__
>> +#define COMPAT_ELF_PLATFORM        ("aarch64_be:ilp32")
>> +#else
>> +#define COMPAT_ELF_PLATFORM        ("aarch64:ilp32")
>> +#endif
> fs/binfmt_elf.c use ELF_PLATFORM instead of the COMPAT one. Should we define
> ELF_PLATFORM directly?
> #undef ELF_PLATFORM
> #ifdef __AARCH64EB__
> #define ELF_PLATFORM            ("aarch64_be:ilp32")
> #else
> #define ELF_PLATFORM            ("aarch64:ilp32")
> #endif
>
> Regards
>
> Bamvor
>> +
>> +#undef ELF_HWCAP
>> +#undef ELF_HWCAP2
>> +#define ELF_HWCAP            ((u32) elf_hwcap)
>> +#define ELF_HWCAP2            ((u32) (elf_hwcap >> 32))
>> +
>> +/*
>> + * Rename a few of the symbols that binfmt_elf.c will define.
>> + * These are all local so the names don't really matter, but it
>> + * might make some debugging less confusing not to duplicate them.
>> + */
>> +#define elf_format        compat_elf_format
>> +#define init_elf_binfmt        init_compat_elf_binfmt
>> +#define exit_elf_binfmt        exit_compat_elf_binfmt
>> +
>> +#include "../../../fs/binfmt_elf.c"
>>
>