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

["Zhangjian (Bamvor)" <bamvor dot zhangjian at huawei dot 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"