On Fri, Dec 27, 2019 at 04:07:03AM +0000, Justin Hibbits wrote:
> Author: jhibbits
> Date: Fri Dec 27 04:07:03 2019
> New Revision: 356113
> URL: https://svnweb.freebsd.org/changeset/base/356113
>
> Log:
> Eliminate the last MI difference in AT_* definitions (for powerpc).
>
> Summary:
> As a transition aide, implement an alternative elfN_freebsd_fixup which
> is called for old powerpc binaries. Similarly, add a translation to rtld to
> convert old values to new ones (as expected by a new rtld).
>
> Translation of old<->new values is incomplete, but sufficient to allow an
> installworld of a new userspace from an old one when a new kernel is
> running.
>
> Test Plan:
> Someone needs to see how a new kernel/rtld/libc works with an old
> binary. If if works we can probalby ship this. If not we probalby need
> some more compat bits.
>
> Submitted by: brooks
> Reviewed by: jhibbits
> Differential Revision: https://reviews.freebsd.org/D20799
>
> Modified:
> head/libexec/rtld-elf/rtld.c
> head/sys/kern/imgact_elf.c
> head/sys/sys/elf_common.h
> head/sys/sys/param.h
>
> Modified: head/libexec/rtld-elf/rtld.c
> ==============================================================================
> --- head/libexec/rtld-elf/rtld.c Fri Dec 27 04:00:04 2019
> (r356112)
> +++ head/libexec/rtld-elf/rtld.c Fri Dec 27 04:07:03 2019
> (r356113)
> @@ -382,6 +382,9 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entr
> caddr_t imgentry;
> char buf[MAXPATHLEN];
> int argc, fd, i, phnum, rtld_argc;
> +#ifdef __powerpc__
> + int old_auxv_format = 1;
> +#endif
> bool dir_enable, explicit_fd, search_in_path;
>
> /*
> @@ -407,7 +410,28 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entr
> for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
> if (auxp->a_type < AT_COUNT)
> aux_info[auxp->a_type] = auxp;
> +#ifdef __powerpc__
> + if (auxp->a_type == 23) /* AT_STACKPROT */
> + old_auxv_format = 0;
> +#endif
> }
> +
> +#ifdef __powerpc__
> + if (old_auxv_format) {
> + /* Remap from old-style auxv numbers. */
> + aux_info[23] = aux_info[21]; /* AT_STACKPROT */
> + aux_info[21] = aux_info[19]; /* AT_PAGESIZESLEN */
> + aux_info[19] = aux_info[17]; /* AT_NCPUS */
> + aux_info[17] = aux_info[15]; /* AT_CANARYLEN */
> + aux_info[15] = aux_info[13]; /* AT_EXECPATH */
> + aux_info[13] = NULL; /* AT_GID */
> +
> + aux_info[20] = aux_info[18]; /* AT_PAGESIZES */
> + aux_info[18] = aux_info[16]; /* AT_OSRELDATE */
> + aux_info[16] = aux_info[14]; /* AT_CANARY */
> + aux_info[14] = NULL; /* AT_EGID */
> + }
> +#endif
>
> /* Initialize and relocate ourselves. */
> assert(aux_info[AT_BASE] != NULL);
>
> Modified: head/sys/kern/imgact_elf.c
> ==============================================================================
> --- head/sys/kern/imgact_elf.c Fri Dec 27 04:00:04 2019
> (r356112)
> +++ head/sys/kern/imgact_elf.c Fri Dec 27 04:07:03 2019
> (r356113)
> @@ -1323,6 +1323,102 @@ ret:
>
> #define suword __CONCAT(suword, __ELF_WORD_SIZE)
>
> +#ifdef __powerpc__
> +#define OLD_AT_NULL AT_NULL
> +#define OLD_AT_IGNORE AT_IGNORE
> +#define OLD_AT_EXECFD AT_EXECFD
> +#define OLD_AT_PHDR AT_PHDR
> +#define OLD_AT_PHENT AT_PHENT
> +#define OLD_AT_PHNUM AT_PHNUM
> +#define OLD_AT_PAGESZ AT_PAGESZ
> +#define OLD_AT_BASE AT_BASE
> +#define OLD_AT_FLAGS AT_FLAGS
> +#define OLD_AT_ENTRY AT_ENTRY
> +#define OLD_AT_NOTELF AT_NOTELF
> +#define OLD_AT_UID AT_UID
> +#define OLD_AT_EUID AT_EUID
> +#define OLD_AT_EXECPATH 13
> +#define OLD_AT_CANARY 14
> +#define OLD_AT_CANARYLEN 15
> +#define OLD_AT_OSRELDATE 16
> +#define OLD_AT_NCPUS 17
> +#define OLD_AT_PAGESIZES 18
> +#define OLD_AT_PAGESIZESLEN 19
> +#define OLD_AT_STACKPROT 21
> +#define OLD_AT_TIMEKEEP AT_TIMEKEEP
> +#define OLD_AT_EHDRFLAGS AT_EHDRFLAGS
> +#define OLD_AT_HWCAP AT_HWCAP
> +#define OLD_AT_HWCAP2 AT_HWCAP2
> +
> +#define OLD_AT_COUNT 27 /* Count of defined aux entry types. */
Arguably these definitions must be in powerpc/include/elf.h.
Then you could use symbolic names in the rtld hack.
Ideally the rtld hack would be moved to powerpc64 subdirectory as well,
by providing an inline function, trivial on other arches.
> +
> +static int
> +__elfN(freebsd_fixup_old_auxargs)(register_t **stack_base,
> + struct image_params *imgp)
> +{
> + Elf_Auxargs *args = (Elf_Auxargs *)imgp->auxargs;
> + Elf_Auxinfo *argarray, *pos;
> + Elf_Addr *base, *auxbase;
> + int error;
> +
> + base = (Elf_Addr *)*stack_base;
> + auxbase = base + imgp->args->argc + 1 + imgp->args->envc + 1;
> + argarray = pos = malloc(OLD_AT_COUNT * sizeof(*pos), M_TEMP,
> + M_WAITOK | M_ZERO);
> +
> + if (args->execfd != -1)
> + AUXARGS_ENTRY(pos, OLD_AT_EXECFD, args->execfd);
> + AUXARGS_ENTRY(pos, OLD_AT_PHDR, args->phdr);
> + AUXARGS_ENTRY(pos, OLD_AT_PHENT, args->phent);
> + AUXARGS_ENTRY(pos, OLD_AT_PHNUM, args->phnum);
> + AUXARGS_ENTRY(pos, OLD_AT_PAGESZ, args->pagesz);
> + AUXARGS_ENTRY(pos, OLD_AT_FLAGS, args->flags);
> + AUXARGS_ENTRY(pos, OLD_AT_ENTRY, args->entry);
> + AUXARGS_ENTRY(pos, OLD_AT_BASE, args->base);
> + AUXARGS_ENTRY(pos, OLD_AT_EHDRFLAGS, args->hdr_eflags);
> + if (imgp->execpathp != 0)
> + AUXARGS_ENTRY(pos, OLD_AT_EXECPATH, imgp->execpathp);
> + AUXARGS_ENTRY(pos, OLD_AT_OSRELDATE,
> + imgp->proc->p_ucred->cr_prison->pr_osreldate);
> + if (imgp->canary != 0) {
> + AUXARGS_ENTRY(pos, OLD_AT_CANARY, imgp->canary);
> + AUXARGS_ENTRY(pos, OLD_AT_CANARYLEN, imgp->canarylen);
> + }
> + AUXARGS_ENTRY(pos, OLD_AT_NCPUS, mp_ncpus);
> + if (imgp->pagesizes != 0) {
> + AUXARGS_ENTRY(pos, OLD_AT_PAGESIZES, imgp->pagesizes);
> + AUXARGS_ENTRY(pos, OLD_AT_PAGESIZESLEN, imgp->pagesizeslen);
> + }
> + if (imgp->sysent->sv_timekeep_base != 0) {
> + AUXARGS_ENTRY(pos, OLD_AT_TIMEKEEP,
> + imgp->sysent->sv_timekeep_base);
> + }
> + AUXARGS_ENTRY(pos, OLD_AT_STACKPROT, imgp->sysent->sv_shared_page_obj
> + != NULL && imgp->stack_prot != 0 ? imgp->stack_prot :
> + imgp->sysent->sv_stackprot);
> + if (imgp->sysent->sv_hwcap != NULL)
> + AUXARGS_ENTRY(pos, OLD_AT_HWCAP, *imgp->sysent->sv_hwcap);
> + if (imgp->sysent->sv_hwcap2 != NULL)
> + AUXARGS_ENTRY(pos, OLD_AT_HWCAP2, *imgp->sysent->sv_hwcap2);
> + AUXARGS_ENTRY(pos, OLD_AT_NULL, 0);
> +
> + free(imgp->auxargs, M_TEMP);
> + imgp->auxargs = NULL;
> + KASSERT(pos - argarray <= OLD_AT_COUNT, ("Too many auxargs"));
> +
> + error = copyout(argarray, auxbase, sizeof(*argarray) * OLD_AT_COUNT);
> + free(argarray, M_TEMP);
> + if (error != 0)
> + return (error);
> +
> + base--;
> + if (suword(base, imgp->args->argc) == -1)
> + return (EFAULT);
> + *stack_base = (register_t *)base;
> + return (0);
> +}
> +#endif /* __powerpc__ */
> +
> int
> __elfN(freebsd_copyout_auxargs)(struct image_params *imgp, uintptr_t base)
> {
> @@ -1382,6 +1478,11 @@ int
> __elfN(freebsd_fixup)(uintptr_t *stack_base, struct image_params *imgp)
> {
> Elf_Addr *base;
> +
> +#ifdef __powerpc__
> + if (imgp->proc->p_osrel < P_OSREL_POWERPC_NEW_AUX_ARGS)
> + return (__elfN(freebsd_fixup_old_auxargs)(stack_base, imgp));
> +#endif /* __powerpc__ */
And this must be moved to powerpc/powerpc/elf_machdep.c by providing
MD variant of sv_fixup, instead of contaminating the MI code.
>
> base = (Elf_Addr *)*stack_base;
> base--;
>
> Modified: head/sys/sys/elf_common.h
> ==============================================================================
> --- head/sys/sys/elf_common.h Fri Dec 27 04:00:04 2019 (r356112)
> +++ head/sys/sys/elf_common.h Fri Dec 27 04:07:03 2019 (r356113)
> @@ -935,7 +935,6 @@ typedef struct {
> #define AT_NOTELF 10 /* Program is not ELF ?? */
> #define AT_UID 11 /* Real uid. */
> #define AT_EUID 12 /* Effective uid. */
> -#ifndef __powerpc__
> #define AT_GID 13 /* Real gid. */
> #define AT_EGID 14 /* Effective gid. */
> #define AT_EXECPATH 15 /* Path to the executable. */
> @@ -945,20 +944,8 @@ typedef struct {
> #define AT_NCPUS 19 /* Number of CPUs. */
> #define AT_PAGESIZES 20 /* Pagesizes. */
> #define AT_PAGESIZESLEN 21 /* Number of pagesizes. */
> -#else /* defined(__powerpc__) */
> -#define AT_EXECPATH 13
> -#define AT_CANARY 14
> -#define AT_CANARYLEN 15
> -#define AT_OSRELDATE 16
> -#define AT_NCPUS 17
> -#define AT_PAGESIZES 18
> -#define AT_PAGESIZESLEN 19
> -#define AT_STACKPROT 21
> -#endif /* defined(__powerpc__) */
> #define AT_TIMEKEEP 22 /* Pointer to timehands. */
> -#ifndef __powerpc__
> #define AT_STACKPROT 23 /* Initial stack protection. */
> -#endif
> #define AT_EHDRFLAGS 24 /* e_flags field from elf hdr */
> #define AT_HWCAP 25 /* CPU feature flags. */
> #define AT_HWCAP2 26 /* CPU feature flags 2. */
>
> Modified: head/sys/sys/param.h
> ==============================================================================
> --- head/sys/sys/param.h Fri Dec 27 04:00:04 2019 (r356112)
> +++ head/sys/sys/param.h Fri Dec 27 04:07:03 2019 (r356113)
> @@ -60,7 +60,7 @@
> * in the range 5 to 9.
> */
> #undef __FreeBSD_version
> -#define __FreeBSD_version 1300069 /* Master, propagated to newvers */
> +#define __FreeBSD_version 1300070 /* Master, propagated to newvers */
>
> /*
> * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,
> @@ -90,6 +90,7 @@
> #define P_OSREL_VMTOTAL64 1200054
> #define P_OSREL_CK_SUPERBLOCK 1300000
> #define P_OSREL_CK_INODE 1300005
> +#define P_OSREL_POWERPC_NEW_AUX_ARGS 1300070
>
> #define P_OSREL_MAJOR(x) ((x) / 100000)
> #endif
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