* [PATCH] riscv: Remove support for variable page sizes
@ 2019-09-30 12:45 Florian Weimer
2019-10-07 16:21 ` RISC-V maintainer review of glibc patch needed (was: Re: [PATCH] riscv: Remove support for variable page sizes) Florian Weimer
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Florian Weimer @ 2019-09-30 12:45 UTC (permalink / raw)
To: libc-alpha; +Cc: Palmer Dabbelt, Jim Wilson, DJ Delorie
[NB: I could use some help with testing here.]
_dl_var_init is used to patch the read-only data section after
relocation. Several architectures use this to update
GLRO(page_size) with the correct value for the static dlopen case,
where _rtld_global_ro has not been initialized by the dynamic
loader.
RISC-V does not need this. The RISC-V Instruction Set Manual,
Volume II: Privileged Architecture, Document Version
20190608-Priv-MSU-Ratified says this:
After much deliberation, we have settled on a conventional
page size of 4 KiB for both RV32 and RV64. We expect this
decision to ease the porting of low-level runtime software
and device drivers. The TLB reach problem is ameliorated by
transparent superpage support in modern operating systems
[2]. Additionally, multi-level TLB hierarchies are quite
inexpensive relative to the multi-level cache hierarchies
whose address space they map.
[2] Juan Navarro, Sitaram Iyer, Peter Druschel, and
Alan Cox. Practical, transparent operating system support
for superpages. SIGOPS Oper. Syst. Rev., 36(SI):89–104,
December 2002.
This means that the initialization of
_rtld_global_ro._dl_page_size in elf/rtld.c with EXEC_PAGESIZE
is sufficient for RISC-V.
2019-09-30 Florian Weimer <fweimer@redhat.com>
riscv: Remove support for variable page sizes.
* sysdeps/unix/sysv/linux/riscv/Makefile [$(subdir) == elf]
(sysdep_routines): Do not add dl-static.
* sysdeps/unix/sysv/linux/riscv/dl-static.c: Remove file.
* sysdeps/unix/sysv/linux/riscv/ldsodefs.h: Likewise.
diff --git a/sysdeps/unix/sysv/linux/riscv/Makefile b/sysdeps/unix/sysv/linux/riscv/Makefile
index b47858769f..b7ad31885c 100644
--- a/sysdeps/unix/sysv/linux/riscv/Makefile
+++ b/sysdeps/unix/sysv/linux/riscv/Makefile
@@ -1,9 +1,5 @@
ifeq ($(subdir),elf)
sysdep_routines += dl-vdso
-ifeq ($(build-shared),yes)
-# This is needed for DSO loading from static binaries.
-sysdep-dl-routines += dl-static
-endif
endif
ifeq ($(subdir),misc)
diff --git a/sysdeps/unix/sysv/linux/riscv/dl-static.c b/sysdeps/unix/sysv/linux/riscv/dl-static.c
deleted file mode 100644
index e52612a267..0000000000
--- a/sysdeps/unix/sysv/linux/riscv/dl-static.c
+++ /dev/null
@@ -1,84 +0,0 @@
-/* Variable initialization. RISC-V version
- Copyright (C) 2001-2019 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
-
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version.
-
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library. If not, see
- <https://www.gnu.org/licenses/>. */
-
-#include <ldsodefs.h>
-
-#ifdef SHARED
-
-void
-_dl_var_init (void *array[])
-{
- /* It has to match "variables" below. */
- enum
- {
- DL_PAGESIZE = 0
- };
-
- GLRO(dl_pagesize) = *((size_t *) array[DL_PAGESIZE]);
-}
-
-#else
-
-static void *variables[] =
-{
- &GLRO(dl_pagesize)
-};
-
-static void
-_dl_unprotect_relro (struct link_map *l)
-{
- ElfW(Addr) start = ((l->l_addr + l->l_relro_addr)
- & ~(GLRO(dl_pagesize) - 1));
- ElfW(Addr) end = ((l->l_addr + l->l_relro_addr + l->l_relro_size)
- & ~(GLRO(dl_pagesize) - 1));
-
- if (start != end)
- __mprotect ((void *) start, end - start, PROT_READ | PROT_WRITE);
-}
-
-void
-_dl_static_init (struct link_map *l)
-{
- struct link_map *rtld_map = l;
- struct r_scope_elem **scope;
- const ElfW(Sym) *ref = NULL;
- lookup_t loadbase;
- void (*f) (void *[]);
- size_t i;
-
- loadbase = _dl_lookup_symbol_x ("_dl_var_init", l, &ref, l->l_local_scope,
- NULL, 0, 1, NULL);
-
- for (scope = l->l_local_scope; *scope != NULL; scope++)
- for (i = 0; i < (*scope)->r_nlist; i++)
- if ((*scope)->r_list[i] == loadbase)
- {
- rtld_map = (*scope)->r_list[i];
- break;
- }
-
- if (ref != NULL)
- {
- f = (void (*) (void *[])) DL_SYMBOL_ADDRESS (loadbase, ref);
- _dl_unprotect_relro (rtld_map);
- f (variables);
- _dl_protect_relro (rtld_map);
- }
-}
-
-#endif
diff --git a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h b/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
deleted file mode 100644
index a46e676752..0000000000
--- a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
+++ /dev/null
@@ -1,32 +0,0 @@
-/* RISC-V dynamic linker data structures for loaded ELF shared objects.
- Copyright (C) 2001-2019 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
-
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version.
-
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library. If not, see
- <https://www.gnu.org/licenses/>. */
-
-#ifndef _LDSODEFS_H
-
-/* Get the real definitions. */
-#include_next <ldsodefs.h>
-
-/* Now define our stuff. */
-
-/* We need special support to initialize DSO loaded for statically linked
- binaries. */
-extern void _dl_static_init (struct link_map *map);
-#undef DL_STATIC_INIT
-#define DL_STATIC_INIT(map) _dl_static_init (map)
-
-#endif /* ldsodefs.h */
^ permalink raw reply [flat|nested] 6+ messages in thread
* RISC-V maintainer review of glibc patch needed (was: Re: [PATCH] riscv: Remove support for variable page sizes)
2019-09-30 12:45 [PATCH] riscv: Remove support for variable page sizes Florian Weimer
@ 2019-10-07 16:21 ` Florian Weimer
2019-10-07 16:50 ` Andrew Waterman
2019-10-07 21:08 ` [PATCH] riscv: Remove support for variable page sizes Alistair Francis
2019-10-08 22:48 ` Jim Wilson
2 siblings, 1 reply; 6+ messages in thread
From: Florian Weimer @ 2019-10-07 16:21 UTC (permalink / raw)
To: libc-alpha, isa-dev, linux-riscv
Cc: Palmer Dabbelt, Jim Wilson, DJ Delorie, andrew, krste, binutils, gcc
Ping. I need a review of this glibc patch from a RISC-V architecture
maintainer:
<https://sourceware.org/ml/libc-alpha/2019-09/msg00506.html>
I believe this is another artifact needlessly copied over from the MIPS
port of glibc, but this one we can fix easily.
Thanks,
Florian
* Florian Weimer:
> _dl_var_init is used to patch the read-only data section after
> relocation. Several architectures use this to update
> GLRO(page_size) with the correct value for the static dlopen case,
> where _rtld_global_ro has not been initialized by the dynamic
> loader.
>
> RISC-V does not need this. The RISC-V Instruction Set Manual,
> Volume II: Privileged Architecture, Document Version
> 20190608-Priv-MSU-Ratified says this:
>
> After much deliberation, we have settled on a conventional
> page size of 4 KiB for both RV32 and RV64. We expect this
> decision to ease the porting of low-level runtime software
> and device drivers. The TLB reach problem is ameliorated by
> transparent superpage support in modern operating systems
> [2]. Additionally, multi-level TLB hierarchies are quite
> inexpensive relative to the multi-level cache hierarchies
> whose address space they map.
>
> [2] Juan Navarro, Sitaram Iyer, Peter Druschel, and
> Alan Cox. Practical, transparent operating system support
> for superpages. SIGOPS Oper. Syst. Rev., 36(SI):89–104,
> December 2002.
>
> This means that the initialization of
> _rtld_global_ro._dl_page_size in elf/rtld.c with EXEC_PAGESIZE
> is sufficient for RISC-V.
>
> 2019-09-30 Florian Weimer <fweimer@redhat.com>
>
> riscv: Remove support for variable page sizes.
> * sysdeps/unix/sysv/linux/riscv/Makefile [$(subdir) == elf]
> (sysdep_routines): Do not add dl-static.
> * sysdeps/unix/sysv/linux/riscv/dl-static.c: Remove file.
> * sysdeps/unix/sysv/linux/riscv/ldsodefs.h: Likewise.
>
> diff --git a/sysdeps/unix/sysv/linux/riscv/Makefile b/sysdeps/unix/sysv/linux/riscv/Makefile
> index b47858769f..b7ad31885c 100644
> --- a/sysdeps/unix/sysv/linux/riscv/Makefile
> +++ b/sysdeps/unix/sysv/linux/riscv/Makefile
> @@ -1,9 +1,5 @@
> ifeq ($(subdir),elf)
> sysdep_routines += dl-vdso
> -ifeq ($(build-shared),yes)
> -# This is needed for DSO loading from static binaries.
> -sysdep-dl-routines += dl-static
> -endif
> endif
>
> ifeq ($(subdir),misc)
> diff --git a/sysdeps/unix/sysv/linux/riscv/dl-static.c b/sysdeps/unix/sysv/linux/riscv/dl-static.c
> deleted file mode 100644
> index e52612a267..0000000000
> --- a/sysdeps/unix/sysv/linux/riscv/dl-static.c
> +++ /dev/null
> @@ -1,84 +0,0 @@
> -/* Variable initialization. RISC-V version
> - Copyright (C) 2001-2019 Free Software Foundation, Inc.
> - This file is part of the GNU C Library.
> -
> - The GNU C Library is free software; you can redistribute it and/or
> - modify it under the terms of the GNU Lesser General Public
> - License as published by the Free Software Foundation; either
> - version 2.1 of the License, or (at your option) any later version.
> -
> - The GNU C Library is distributed in the hope that it will be useful,
> - but WITHOUT ANY WARRANTY; without even the implied warranty of
> - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - Lesser General Public License for more details.
> -
> - You should have received a copy of the GNU Lesser General Public
> - License along with the GNU C Library. If not, see
> - <https://www.gnu.org/licenses/>. */
> -
> -#include <ldsodefs.h>
> -
> -#ifdef SHARED
> -
> -void
> -_dl_var_init (void *array[])
> -{
> - /* It has to match "variables" below. */
> - enum
> - {
> - DL_PAGESIZE = 0
> - };
> -
> - GLRO(dl_pagesize) = *((size_t *) array[DL_PAGESIZE]);
> -}
> -
> -#else
> -
> -static void *variables[] =
> -{
> - &GLRO(dl_pagesize)
> -};
> -
> -static void
> -_dl_unprotect_relro (struct link_map *l)
> -{
> - ElfW(Addr) start = ((l->l_addr + l->l_relro_addr)
> - & ~(GLRO(dl_pagesize) - 1));
> - ElfW(Addr) end = ((l->l_addr + l->l_relro_addr + l->l_relro_size)
> - & ~(GLRO(dl_pagesize) - 1));
> -
> - if (start != end)
> - __mprotect ((void *) start, end - start, PROT_READ | PROT_WRITE);
> -}
> -
> -void
> -_dl_static_init (struct link_map *l)
> -{
> - struct link_map *rtld_map = l;
> - struct r_scope_elem **scope;
> - const ElfW(Sym) *ref = NULL;
> - lookup_t loadbase;
> - void (*f) (void *[]);
> - size_t i;
> -
> - loadbase = _dl_lookup_symbol_x ("_dl_var_init", l, &ref, l->l_local_scope,
> - NULL, 0, 1, NULL);
> -
> - for (scope = l->l_local_scope; *scope != NULL; scope++)
> - for (i = 0; i < (*scope)->r_nlist; i++)
> - if ((*scope)->r_list[i] == loadbase)
> - {
> - rtld_map = (*scope)->r_list[i];
> - break;
> - }
> -
> - if (ref != NULL)
> - {
> - f = (void (*) (void *[])) DL_SYMBOL_ADDRESS (loadbase, ref);
> - _dl_unprotect_relro (rtld_map);
> - f (variables);
> - _dl_protect_relro (rtld_map);
> - }
> -}
> -
> -#endif
> diff --git a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h b/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
> deleted file mode 100644
> index a46e676752..0000000000
> --- a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
> +++ /dev/null
> @@ -1,32 +0,0 @@
> -/* RISC-V dynamic linker data structures for loaded ELF shared objects.
> - Copyright (C) 2001-2019 Free Software Foundation, Inc.
> - This file is part of the GNU C Library.
> -
> - The GNU C Library is free software; you can redistribute it and/or
> - modify it under the terms of the GNU Lesser General Public
> - License as published by the Free Software Foundation; either
> - version 2.1 of the License, or (at your option) any later version.
> -
> - The GNU C Library is distributed in the hope that it will be useful,
> - but WITHOUT ANY WARRANTY; without even the implied warranty of
> - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - Lesser General Public License for more details.
> -
> - You should have received a copy of the GNU Lesser General Public
> - License along with the GNU C Library. If not, see
> - <https://www.gnu.org/licenses/>. */
> -
> -#ifndef _LDSODEFS_H
> -
> -/* Get the real definitions. */
> -#include_next <ldsodefs.h>
> -
> -/* Now define our stuff. */
> -
> -/* We need special support to initialize DSO loaded for statically linked
> - binaries. */
> -extern void _dl_static_init (struct link_map *map);
> -#undef DL_STATIC_INIT
> -#define DL_STATIC_INIT(map) _dl_static_init (map)
> -
> -#endif /* ldsodefs.h */
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: RISC-V maintainer review of glibc patch needed (was: Re: [PATCH] riscv: Remove support for variable page sizes)
2019-10-07 16:21 ` RISC-V maintainer review of glibc patch needed (was: Re: [PATCH] riscv: Remove support for variable page sizes) Florian Weimer
@ 2019-10-07 16:50 ` Andrew Waterman
0 siblings, 0 replies; 6+ messages in thread
From: Andrew Waterman @ 2019-10-07 16:50 UTC (permalink / raw)
To: Florian Weimer
Cc: libc-alpha, Palmer Dabbelt, Jim Wilson, DJ Delorie,
Krste Asanovic, binutils, GCC Development
LGTM; I believe you are right on both counts that this was borrowed
from MIPS and that we do not need this for RISC-V.
On Mon, Oct 7, 2019 at 6:21 PM Florian Weimer <fweimer@redhat.com> wrote:
>
> Ping. I need a review of this glibc patch from a RISC-V architecture
> maintainer:
>
> <https://sourceware.org/ml/libc-alpha/2019-09/msg00506.html>
>
> I believe this is another artifact needlessly copied over from the MIPS
> port of glibc, but this one we can fix easily.
>
> Thanks,
> Florian
>
> * Florian Weimer:
>
> > _dl_var_init is used to patch the read-only data section after
> > relocation. Several architectures use this to update
> > GLRO(page_size) with the correct value for the static dlopen case,
> > where _rtld_global_ro has not been initialized by the dynamic
> > loader.
> >
> > RISC-V does not need this. The RISC-V Instruction Set Manual,
> > Volume II: Privileged Architecture, Document Version
> > 20190608-Priv-MSU-Ratified says this:
> >
> > After much deliberation, we have settled on a conventional
> > page size of 4 KiB for both RV32 and RV64. We expect this
> > decision to ease the porting of low-level runtime software
> > and device drivers. The TLB reach problem is ameliorated by
> > transparent superpage support in modern operating systems
> > [2]. Additionally, multi-level TLB hierarchies are quite
> > inexpensive relative to the multi-level cache hierarchies
> > whose address space they map.
> >
> > [2] Juan Navarro, Sitaram Iyer, Peter Druschel, and
> > Alan Cox. Practical, transparent operating system support
> > for superpages. SIGOPS Oper. Syst. Rev., 36(SI):89–104,
> > December 2002.
> >
> > This means that the initialization of
> > _rtld_global_ro._dl_page_size in elf/rtld.c with EXEC_PAGESIZE
> > is sufficient for RISC-V.
> >
> > 2019-09-30 Florian Weimer <fweimer@redhat.com>
> >
> > riscv: Remove support for variable page sizes.
> > * sysdeps/unix/sysv/linux/riscv/Makefile [$(subdir) == elf]
> > (sysdep_routines): Do not add dl-static.
> > * sysdeps/unix/sysv/linux/riscv/dl-static.c: Remove file.
> > * sysdeps/unix/sysv/linux/riscv/ldsodefs.h: Likewise.
> >
> > diff --git a/sysdeps/unix/sysv/linux/riscv/Makefile b/sysdeps/unix/sysv/linux/riscv/Makefile
> > index b47858769f..b7ad31885c 100644
> > --- a/sysdeps/unix/sysv/linux/riscv/Makefile
> > +++ b/sysdeps/unix/sysv/linux/riscv/Makefile
> > @@ -1,9 +1,5 @@
> > ifeq ($(subdir),elf)
> > sysdep_routines += dl-vdso
> > -ifeq ($(build-shared),yes)
> > -# This is needed for DSO loading from static binaries.
> > -sysdep-dl-routines += dl-static
> > -endif
> > endif
> >
> > ifeq ($(subdir),misc)
> > diff --git a/sysdeps/unix/sysv/linux/riscv/dl-static.c b/sysdeps/unix/sysv/linux/riscv/dl-static.c
> > deleted file mode 100644
> > index e52612a267..0000000000
> > --- a/sysdeps/unix/sysv/linux/riscv/dl-static.c
> > +++ /dev/null
> > @@ -1,84 +0,0 @@
> > -/* Variable initialization. RISC-V version
> > - Copyright (C) 2001-2019 Free Software Foundation, Inc.
> > - This file is part of the GNU C Library.
> > -
> > - The GNU C Library is free software; you can redistribute it and/or
> > - modify it under the terms of the GNU Lesser General Public
> > - License as published by the Free Software Foundation; either
> > - version 2.1 of the License, or (at your option) any later version.
> > -
> > - The GNU C Library is distributed in the hope that it will be useful,
> > - but WITHOUT ANY WARRANTY; without even the implied warranty of
> > - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > - Lesser General Public License for more details.
> > -
> > - You should have received a copy of the GNU Lesser General Public
> > - License along with the GNU C Library. If not, see
> > - <https://www.gnu.org/licenses/>. */
> > -
> > -#include <ldsodefs.h>
> > -
> > -#ifdef SHARED
> > -
> > -void
> > -_dl_var_init (void *array[])
> > -{
> > - /* It has to match "variables" below. */
> > - enum
> > - {
> > - DL_PAGESIZE = 0
> > - };
> > -
> > - GLRO(dl_pagesize) = *((size_t *) array[DL_PAGESIZE]);
> > -}
> > -
> > -#else
> > -
> > -static void *variables[] =
> > -{
> > - &GLRO(dl_pagesize)
> > -};
> > -
> > -static void
> > -_dl_unprotect_relro (struct link_map *l)
> > -{
> > - ElfW(Addr) start = ((l->l_addr + l->l_relro_addr)
> > - & ~(GLRO(dl_pagesize) - 1));
> > - ElfW(Addr) end = ((l->l_addr + l->l_relro_addr + l->l_relro_size)
> > - & ~(GLRO(dl_pagesize) - 1));
> > -
> > - if (start != end)
> > - __mprotect ((void *) start, end - start, PROT_READ | PROT_WRITE);
> > -}
> > -
> > -void
> > -_dl_static_init (struct link_map *l)
> > -{
> > - struct link_map *rtld_map = l;
> > - struct r_scope_elem **scope;
> > - const ElfW(Sym) *ref = NULL;
> > - lookup_t loadbase;
> > - void (*f) (void *[]);
> > - size_t i;
> > -
> > - loadbase = _dl_lookup_symbol_x ("_dl_var_init", l, &ref, l->l_local_scope,
> > - NULL, 0, 1, NULL);
> > -
> > - for (scope = l->l_local_scope; *scope != NULL; scope++)
> > - for (i = 0; i < (*scope)->r_nlist; i++)
> > - if ((*scope)->r_list[i] == loadbase)
> > - {
> > - rtld_map = (*scope)->r_list[i];
> > - break;
> > - }
> > -
> > - if (ref != NULL)
> > - {
> > - f = (void (*) (void *[])) DL_SYMBOL_ADDRESS (loadbase, ref);
> > - _dl_unprotect_relro (rtld_map);
> > - f (variables);
> > - _dl_protect_relro (rtld_map);
> > - }
> > -}
> > -
> > -#endif
> > diff --git a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h b/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
> > deleted file mode 100644
> > index a46e676752..0000000000
> > --- a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
> > +++ /dev/null
> > @@ -1,32 +0,0 @@
> > -/* RISC-V dynamic linker data structures for loaded ELF shared objects.
> > - Copyright (C) 2001-2019 Free Software Foundation, Inc.
> > - This file is part of the GNU C Library.
> > -
> > - The GNU C Library is free software; you can redistribute it and/or
> > - modify it under the terms of the GNU Lesser General Public
> > - License as published by the Free Software Foundation; either
> > - version 2.1 of the License, or (at your option) any later version.
> > -
> > - The GNU C Library is distributed in the hope that it will be useful,
> > - but WITHOUT ANY WARRANTY; without even the implied warranty of
> > - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > - Lesser General Public License for more details.
> > -
> > - You should have received a copy of the GNU Lesser General Public
> > - License along with the GNU C Library. If not, see
> > - <https://www.gnu.org/licenses/>. */
> > -
> > -#ifndef _LDSODEFS_H
> > -
> > -/* Get the real definitions. */
> > -#include_next <ldsodefs.h>
> > -
> > -/* Now define our stuff. */
> > -
> > -/* We need special support to initialize DSO loaded for statically linked
> > - binaries. */
> > -extern void _dl_static_init (struct link_map *map);
> > -#undef DL_STATIC_INIT
> > -#define DL_STATIC_INIT(map) _dl_static_init (map)
> > -
> > -#endif /* ldsodefs.h */
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] riscv: Remove support for variable page sizes
2019-09-30 12:45 [PATCH] riscv: Remove support for variable page sizes Florian Weimer
2019-10-07 16:21 ` RISC-V maintainer review of glibc patch needed (was: Re: [PATCH] riscv: Remove support for variable page sizes) Florian Weimer
@ 2019-10-07 21:08 ` Alistair Francis
2019-10-08 22:48 ` Jim Wilson
2 siblings, 0 replies; 6+ messages in thread
From: Alistair Francis @ 2019-10-07 21:08 UTC (permalink / raw)
To: Florian Weimer; +Cc: GNU C Library, Palmer Dabbelt, Jim Wilson, DJ Delorie
On Mon, Sep 30, 2019 at 5:46 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> [NB: I could use some help with testing here.]
>
> _dl_var_init is used to patch the read-only data section after
> relocation. Several architectures use this to update
> GLRO(page_size) with the correct value for the static dlopen case,
> where _rtld_global_ro has not been initialized by the dynamic
> loader.
>
> RISC-V does not need this. The RISC-V Instruction Set Manual,
> Volume II: Privileged Architecture, Document Version
> 20190608-Priv-MSU-Ratified says this:
>
> After much deliberation, we have settled on a conventional
> page size of 4 KiB for both RV32 and RV64. We expect this
> decision to ease the porting of low-level runtime software
> and device drivers. The TLB reach problem is ameliorated by
> transparent superpage support in modern operating systems
> [2]. Additionally, multi-level TLB hierarchies are quite
> inexpensive relative to the multi-level cache hierarchies
> whose address space they map.
>
> [2] Juan Navarro, Sitaram Iyer, Peter Druschel, and
> Alan Cox. Practical, transparent operating system support
> for superpages. SIGOPS Oper. Syst. Rev., 36(SI):89–104,
> December 2002.
>
> This means that the initialization of
> _rtld_global_ro._dl_page_size in elf/rtld.c with EXEC_PAGESIZE
> is sufficient for RISC-V.
>
> 2019-09-30 Florian Weimer <fweimer@redhat.com>
>
> riscv: Remove support for variable page sizes.
> * sysdeps/unix/sysv/linux/riscv/Makefile [$(subdir) == elf]
> (sysdep_routines): Do not add dl-static.
> * sysdeps/unix/sysv/linux/riscv/dl-static.c: Remove file.
> * sysdeps/unix/sysv/linux/riscv/ldsodefs.h: Likewise.
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Alistair
>
> diff --git a/sysdeps/unix/sysv/linux/riscv/Makefile b/sysdeps/unix/sysv/linux/riscv/Makefile
> index b47858769f..b7ad31885c 100644
> --- a/sysdeps/unix/sysv/linux/riscv/Makefile
> +++ b/sysdeps/unix/sysv/linux/riscv/Makefile
> @@ -1,9 +1,5 @@
> ifeq ($(subdir),elf)
> sysdep_routines += dl-vdso
> -ifeq ($(build-shared),yes)
> -# This is needed for DSO loading from static binaries.
> -sysdep-dl-routines += dl-static
> -endif
> endif
>
> ifeq ($(subdir),misc)
> diff --git a/sysdeps/unix/sysv/linux/riscv/dl-static.c b/sysdeps/unix/sysv/linux/riscv/dl-static.c
> deleted file mode 100644
> index e52612a267..0000000000
> --- a/sysdeps/unix/sysv/linux/riscv/dl-static.c
> +++ /dev/null
> @@ -1,84 +0,0 @@
> -/* Variable initialization. RISC-V version
> - Copyright (C) 2001-2019 Free Software Foundation, Inc.
> - This file is part of the GNU C Library.
> -
> - The GNU C Library is free software; you can redistribute it and/or
> - modify it under the terms of the GNU Lesser General Public
> - License as published by the Free Software Foundation; either
> - version 2.1 of the License, or (at your option) any later version.
> -
> - The GNU C Library is distributed in the hope that it will be useful,
> - but WITHOUT ANY WARRANTY; without even the implied warranty of
> - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - Lesser General Public License for more details.
> -
> - You should have received a copy of the GNU Lesser General Public
> - License along with the GNU C Library. If not, see
> - <https://www.gnu.org/licenses/>. */
> -
> -#include <ldsodefs.h>
> -
> -#ifdef SHARED
> -
> -void
> -_dl_var_init (void *array[])
> -{
> - /* It has to match "variables" below. */
> - enum
> - {
> - DL_PAGESIZE = 0
> - };
> -
> - GLRO(dl_pagesize) = *((size_t *) array[DL_PAGESIZE]);
> -}
> -
> -#else
> -
> -static void *variables[] =
> -{
> - &GLRO(dl_pagesize)
> -};
> -
> -static void
> -_dl_unprotect_relro (struct link_map *l)
> -{
> - ElfW(Addr) start = ((l->l_addr + l->l_relro_addr)
> - & ~(GLRO(dl_pagesize) - 1));
> - ElfW(Addr) end = ((l->l_addr + l->l_relro_addr + l->l_relro_size)
> - & ~(GLRO(dl_pagesize) - 1));
> -
> - if (start != end)
> - __mprotect ((void *) start, end - start, PROT_READ | PROT_WRITE);
> -}
> -
> -void
> -_dl_static_init (struct link_map *l)
> -{
> - struct link_map *rtld_map = l;
> - struct r_scope_elem **scope;
> - const ElfW(Sym) *ref = NULL;
> - lookup_t loadbase;
> - void (*f) (void *[]);
> - size_t i;
> -
> - loadbase = _dl_lookup_symbol_x ("_dl_var_init", l, &ref, l->l_local_scope,
> - NULL, 0, 1, NULL);
> -
> - for (scope = l->l_local_scope; *scope != NULL; scope++)
> - for (i = 0; i < (*scope)->r_nlist; i++)
> - if ((*scope)->r_list[i] == loadbase)
> - {
> - rtld_map = (*scope)->r_list[i];
> - break;
> - }
> -
> - if (ref != NULL)
> - {
> - f = (void (*) (void *[])) DL_SYMBOL_ADDRESS (loadbase, ref);
> - _dl_unprotect_relro (rtld_map);
> - f (variables);
> - _dl_protect_relro (rtld_map);
> - }
> -}
> -
> -#endif
> diff --git a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h b/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
> deleted file mode 100644
> index a46e676752..0000000000
> --- a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h
> +++ /dev/null
> @@ -1,32 +0,0 @@
> -/* RISC-V dynamic linker data structures for loaded ELF shared objects.
> - Copyright (C) 2001-2019 Free Software Foundation, Inc.
> - This file is part of the GNU C Library.
> -
> - The GNU C Library is free software; you can redistribute it and/or
> - modify it under the terms of the GNU Lesser General Public
> - License as published by the Free Software Foundation; either
> - version 2.1 of the License, or (at your option) any later version.
> -
> - The GNU C Library is distributed in the hope that it will be useful,
> - but WITHOUT ANY WARRANTY; without even the implied warranty of
> - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - Lesser General Public License for more details.
> -
> - You should have received a copy of the GNU Lesser General Public
> - License along with the GNU C Library. If not, see
> - <https://www.gnu.org/licenses/>. */
> -
> -#ifndef _LDSODEFS_H
> -
> -/* Get the real definitions. */
> -#include_next <ldsodefs.h>
> -
> -/* Now define our stuff. */
> -
> -/* We need special support to initialize DSO loaded for statically linked
> - binaries. */
> -extern void _dl_static_init (struct link_map *map);
> -#undef DL_STATIC_INIT
> -#define DL_STATIC_INIT(map) _dl_static_init (map)
> -
> -#endif /* ldsodefs.h */
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] riscv: Remove support for variable page sizes
2019-09-30 12:45 [PATCH] riscv: Remove support for variable page sizes Florian Weimer
2019-10-07 16:21 ` RISC-V maintainer review of glibc patch needed (was: Re: [PATCH] riscv: Remove support for variable page sizes) Florian Weimer
2019-10-07 21:08 ` [PATCH] riscv: Remove support for variable page sizes Alistair Francis
@ 2019-10-08 22:48 ` Jim Wilson
2019-10-09 7:05 ` Florian Weimer
2 siblings, 1 reply; 6+ messages in thread
From: Jim Wilson @ 2019-10-08 22:48 UTC (permalink / raw)
To: Florian Weimer; +Cc: GNU C Library, Palmer Dabbelt, DJ Delorie
On Mon, Sep 30, 2019 at 5:45 AM Florian Weimer <fweimer@redhat.com> wrote:
> [NB: I could use some help with testing here.]
I was out sick most of last week, but I did a top of tree
riscv64-linux native binutils/gcc/glibc build this week which ended up
testing your patch. I got 16 glibc failures which is what I expected.
6 of those are asin/acos ULP problems, so I think only 10 real
problems. I did have to add -Wno-error=stringop-overflow to gccwarn
to complete the glibc build, but I believe that is a gcc bug, and I
see that there are already a number of stringop-overflow bugs that
have been reported, so it might be related to one of the existing bug
reports.
Jim
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] riscv: Remove support for variable page sizes
2019-10-08 22:48 ` Jim Wilson
@ 2019-10-09 7:05 ` Florian Weimer
0 siblings, 0 replies; 6+ messages in thread
From: Florian Weimer @ 2019-10-09 7:05 UTC (permalink / raw)
To: Jim Wilson; +Cc: GNU C Library, Palmer Dabbelt, DJ Delorie
* Jim Wilson:
> On Mon, Sep 30, 2019 at 5:45 AM Florian Weimer <fweimer@redhat.com> wrote:
>> [NB: I could use some help with testing here.]
>
> I was out sick most of last week, but I did a top of tree
> riscv64-linux native binutils/gcc/glibc build this week which ended up
> testing your patch. I got 16 glibc failures which is what I expected.
> 6 of those are asin/acos ULP problems, so I think only 10 real
> problems. I did have to add -Wno-error=stringop-overflow to gccwarn
> to complete the glibc build, but I believe that is a gcc bug, and I
> see that there are already a number of stringop-overflow bugs that
> have been reported, so it might be related to one of the existing bug
> reports.
Thanks for the additional testing.
Florian
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-10-09 7:05 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-30 12:45 [PATCH] riscv: Remove support for variable page sizes Florian Weimer
2019-10-07 16:21 ` RISC-V maintainer review of glibc patch needed (was: Re: [PATCH] riscv: Remove support for variable page sizes) Florian Weimer
2019-10-07 16:50 ` Andrew Waterman
2019-10-07 21:08 ` [PATCH] riscv: Remove support for variable page sizes Alistair Francis
2019-10-08 22:48 ` Jim Wilson
2019-10-09 7:05 ` Florian Weimer
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