2.2.5 plan
Jakub Jelinek
jakub@redhat.com
Thu Jan 3 10:05:00 GMT 2002
On Thu, Jan 03, 2002 at 09:55:17AM -0800, Ulrich Drepper wrote:
> Thorsten Kukuk <kukuk@suse.de> writes:
>
> > What happens with this, or is there a new bug which blocks 2.2.5 ?
>
> I really hoped for some feedback, any feedback. Then came the holiday
> break. I'm just now back and will look at it again.
I'd like to get the following patch in, but haven't managed to test it
extensively yet. Hope to do it very soon.
This patch is port of libgcc_s new EH registry scheme which glibc
_Unwind_Find_FDE needs to support if glibc _Unwind_Find_FDE comes before
libgcc_s _Unwind_Find_FDE in search scope, plus DW_CFA_restore fix and minor
optimization (almost all shared libraries have .eh_frame section 4/8 bytes
long, indicating no eh information, so the is no reason to register them).
2002-01-03 Jakub Jelinek <jakub@redhat.com>
* elf/Makefile (routines, shared-only-routines): Add
unwind-dw2-fde-glibc instead of unwind-dw2-fde.
* elf/elf.h (PT_GNU_EH_FRAME): Define.
* sysdeps/generic/unwind-dw2-fde-glibc.c: New file.
* sysdeps/generic/unwind-dw2-fde.c (__register_frame_info_bases):
Optimize if .eh_frame section contains no FDEs.
(__register_frame, __deregister_frame_info_bases,
__deregister_frame): Likewise.
* sysdeps/generic/unwind-dw2.c (execute_cfa_program): Fix
DW_CFA_restore handling.
--- libc/elf/Makefile 2001/12/27 19:33:10 1.1.1.35
+++ libc/elf/Makefile 2001/12/27 22:58:25 1.15
@@ -67,8 +67,8 @@ distribute := $(rtld-routines:=.c) dynam
include ../Makeconfig
ifeq ($(unwind-find-fde),yes)
-routines += unwind-dw2-fde
-shared-only-routines = unwind-dw2-fde
+routines += unwind-dw2-fde-glibc
+shared-only-routines = unwind-dw2-fde-glibc
endif
before-compile = $(objpfx)trusted-dirs.h
--- libc/elf/elf.h 2001/12/27 19:33:11 1.1.1.26
+++ libc/elf/elf.h 2001/12/27 21:54:33 1.11
@@ -560,6 +560,7 @@ typedef struct
#define PT_TLS 7 /* Thread-local storage segment */
#define PT_NUM 8 /* Number of defined types */
#define PT_LOOS 0x60000000 /* Start of OS-specific */
+#define PT_GNU_EH_FRAME 0x6474e550 /* GCC .eh_frame_hdr segment */
#define PT_HIOS 0x6fffffff /* End of OS-specific */
#define PT_LOPROC 0x70000000 /* Start of processor-specific */
#define PT_HIPROC 0x7fffffff /* End of processor-specific */
--- libc/sysdeps/generic/unwind-dw2-fde-glibc.c Thu Aug 24 05:00:32 2000
+++ libc/sysdeps/generic/unwind-dw2-fde-glibc.c Thu Jan 3 12:09:18 2002
@@ -0,0 +1,279 @@
+/* Copyright (C) 2001 Free Software Foundation, Inc.
+ Contributed by Jakub Jelinek <jakub@redhat.com>.
+
+ This file is part of GNU CC.
+
+ GNU CC is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ GNU CC 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with GNU CC; see the file COPYING. If not, write to
+ the Free Software Foundation, 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+/* As a special exception, if you link this library with other files,
+ some of which are compiled with GCC, to produce an executable,
+ this library does not by itself cause the resulting executable
+ to be covered by the GNU General Public License.
+ This exception does not however invalidate any other reasons why
+ the executable file might be covered by the GNU General Public License. */
+
+/* Locate the FDE entry for a given address, using PT_GNU_EH_FRAME ELF
+ segment and dl_iterate_phdr to avoid register/deregister calls at
+ DSO load/unload. */
+
+#ifdef _LIBC
+# include <shlib-compat.h>
+#endif
+
+#if !defined _LIBC || SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_2_5)
+
+#include <link.h>
+#include <stddef.h>
+
+#define _Unwind_Find_FDE _Unwind_Find_registered_FDE
+
+#include <unwind-dw2-fde.c>
+
+#undef _Unwind_Find_FDE
+
+fde * _Unwind_Find_registered_FDE (void *pc, struct dwarf_eh_bases *bases);
+
+struct unw_eh_callback_data
+{
+ _Unwind_Ptr pc;
+ void *tbase;
+ void *dbase;
+ void *func;
+ fde *ret;
+};
+
+struct unw_eh_frame_hdr
+{
+ unsigned char version;
+ unsigned char eh_frame_ptr_enc;
+ unsigned char fde_count_enc;
+ unsigned char table_enc;
+};
+
+/* Like base_of_encoded_value, but take the base from a struct object
+ instead of an _Unwind_Context. */
+
+static _Unwind_Ptr
+base_from_cb_data (unsigned char encoding, struct unw_eh_callback_data *data)
+{
+ if (encoding == DW_EH_PE_omit)
+ return 0;
+
+ switch (encoding & 0x70)
+ {
+ case DW_EH_PE_absptr:
+ case DW_EH_PE_pcrel:
+ case DW_EH_PE_aligned:
+ return 0;
+
+ case DW_EH_PE_textrel:
+ return (_Unwind_Ptr) data->tbase;
+ case DW_EH_PE_datarel:
+ return (_Unwind_Ptr) data->dbase;
+ }
+ abort ();
+}
+
+static int
+_Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr)
+{
+ struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr;
+ const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic;
+ long n, match;
+ _Unwind_Ptr load_base;
+ const unsigned char *p;
+ const struct unw_eh_frame_hdr *hdr;
+ _Unwind_Ptr eh_frame;
+ struct object ob;
+
+ /* Make sure struct dl_phdr_info is at least as big as we need. */
+ if (size < offsetof (struct dl_phdr_info, dlpi_phnum)
+ + sizeof (info->dlpi_phnum))
+ return -1;
+
+ match = 0;
+ phdr = info->dlpi_phdr;
+ load_base = info->dlpi_addr;
+ p_eh_frame_hdr = NULL;
+ p_dynamic = NULL;
+
+ /* See if PC falls into one of the loaded segments. Find the eh_frame
+ segment at the same time. */
+ for (n = info->dlpi_phnum; --n >= 0; phdr++)
+ {
+ if (phdr->p_type == PT_LOAD)
+ {
+ _Unwind_Ptr vaddr = phdr->p_vaddr + load_base;
+ if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz)
+ match = 1;
+ }
+ else if (phdr->p_type == PT_GNU_EH_FRAME)
+ p_eh_frame_hdr = phdr;
+ else if (phdr->p_type == PT_DYNAMIC)
+ p_dynamic = phdr;
+ }
+ if (!match || !p_eh_frame_hdr)
+ return 0;
+
+ /* Read .eh_frame_hdr header. */
+ hdr = (const struct unw_eh_frame_hdr *)
+ (p_eh_frame_hdr->p_vaddr + load_base);
+ if (hdr->version != 1)
+ return 1;
+
+#ifdef CRT_GET_RFIB_DATA
+# ifdef __i386__
+ data->dbase = NULL;
+ if (p_dynamic)
+ {
+ /* For dynamicly linked executables and shared libraries,
+ DT_PLTGOT is the gp value for that object. */
+ ElfW(Dyn) *dyn = (ElfW(Dyn) *)(p_dynamic->p_vaddr + load_base);
+ for (; dyn->d_tag != DT_NULL ; dyn++)
+ if (dyn->d_tag == DT_PLTGOT)
+ {
+ /* On IA-32, _DYNAMIC is writable and GLIBC has relocated it. */
+ data->dbase = (void *) dyn->d_un.d_ptr;
+ break;
+ }
+ }
+# else
+# error What is DW_EH_PE_datarel base on this platform?
+# endif
+#endif
+#ifdef CRT_GET_RFIB_TEXT
+# error What is DW_EH_PE_textrel base on this platform?
+#endif
+
+ p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc,
+ base_from_cb_data (hdr->eh_frame_ptr_enc,
+ data),
+ (const unsigned char *) (hdr + 1),
+ &eh_frame);
+
+ /* We require here specific table encoding to speed things up.
+ Also, DW_EH_PE_datarel here means using PT_GNU_EH_FRAME start
+ as base, not the processor specific DW_EH_PE_datarel. */
+ if (hdr->fde_count_enc != DW_EH_PE_omit
+ && hdr->table_enc == (DW_EH_PE_datarel | DW_EH_PE_sdata4))
+ {
+ _Unwind_Ptr fde_count;
+
+ p = read_encoded_value_with_base (hdr->fde_count_enc,
+ base_from_cb_data (hdr->fde_count_enc,
+ data),
+ p, &fde_count);
+ /* Shouldn't happen. */
+ if (fde_count == 0)
+ return 1;
+ if ((((_Unwind_Ptr) p) & 3) == 0)
+ {
+ struct fde_table {
+ signed initial_loc __attribute__ ((mode (SI)));
+ signed fde __attribute__ ((mode (SI)));
+ };
+ const struct fde_table *table = (const struct fde_table *) p;
+ size_t lo, hi, mid;
+ _Unwind_Ptr data_base = (_Unwind_Ptr) hdr;
+ fde *f;
+ unsigned int f_enc, f_enc_size;
+ _Unwind_Ptr range;
+
+ mid = fde_count - 1;
+ if (data->pc < table[0].initial_loc + data_base)
+ return 1;
+ else if (data->pc < table[mid].initial_loc + data_base)
+ {
+ lo = 0;
+ hi = mid;
+
+ while (lo < hi)
+ {
+ mid = (lo + hi) / 2;
+ if (data->pc < table[mid].initial_loc + data_base)
+ hi = mid;
+ else if (data->pc >= table[mid + 1].initial_loc + data_base)
+ lo = mid + 1;
+ else
+ break;
+ }
+
+ if (lo >= hi)
+ __gxx_abort ();
+ }
+
+ f = (fde *) (table[mid].fde + data_base);
+ f_enc = get_fde_encoding (f);
+ f_enc_size = size_of_encoded_value (f_enc);
+ read_encoded_value_with_base (f_enc & 0x0f, 0,
+ &f->pc_begin[f_enc_size], &range);
+ if (data->pc < table[mid].initial_loc + data_base + range)
+ data->ret = f;
+ data->func = (void *) (table[mid].initial_loc + data_base);
+ return 1;
+ }
+ }
+
+ /* We have no sorted search table, so need to go the slow way.
+ As soon as GLIBC will provide API so to notify that a library has been
+ removed, we could cache this (and thus use search_object). */
+ ob.pc_begin = NULL;
+ ob.tbase = data->tbase;
+ ob.dbase = data->dbase;
+ ob.u.single = (fde *) eh_frame;
+ ob.s.i = 0;
+ ob.s.b.mixed_encoding = 1; /* Need to assume worst case. */
+ data->ret = linear_search_fdes (&ob, (fde *) eh_frame, (void *) data->pc);
+ if (data->ret != NULL)
+ {
+ unsigned int encoding = get_fde_encoding (data->ret);
+ read_encoded_value_with_base (encoding,
+ base_from_cb_data (encoding, data),
+ data->ret->pc_begin,
+ (_Unwind_Ptr *)&data->func);
+ }
+ return 1;
+}
+
+fde *
+_Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases)
+{
+ struct unw_eh_callback_data data;
+ fde *ret;
+
+ ret = _Unwind_Find_registered_FDE (pc, bases);
+ if (ret != NULL)
+ return ret;
+
+ data.pc = (_Unwind_Ptr) pc;
+ data.tbase = NULL;
+ data.dbase = NULL;
+ data.func = NULL;
+ data.ret = NULL;
+
+ if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0)
+ return NULL;
+
+ if (data.ret)
+ {
+ bases->tbase = data.tbase;
+ bases->dbase = data.dbase;
+ bases->func = data.func;
+ }
+ return data.ret;
+}
+
+#endif
--- libc/sysdeps/generic/unwind-dw2-fde.c 2001/12/27 19:34:14 1.1.1.1
+++ libc/sysdeps/generic/unwind-dw2-fde.c 2001/12/27 21:54:38 1.2
@@ -101,6 +101,10 @@ void
__register_frame_info_bases (void *begin, struct object *ob,
void *tbase, void *dbase)
{
+ /* If .eh_frame is empty, don't register at all. */
+ if (*(uword *)begin == 0)
+ return;
+
ob->pc_begin = (void *)-1;
ob->tbase = tbase;
ob->dbase = dbase;
@@ -126,7 +130,13 @@ __register_frame_info (void *begin, stru
void
__register_frame (void *begin)
{
- struct object *ob = (struct object *) malloc (sizeof (struct object));
+ struct object *ob;
+
+ /* If .eh_frame is empty, don't register at all. */
+ if (*(uword *)begin == 0)
+ return;
+
+ ob = (struct object *) malloc (sizeof (struct object));
__register_frame_info (begin, ob);
}
@@ -186,6 +196,10 @@ __deregister_frame_info_bases (void *beg
struct object **p;
struct object *ob = 0;
+ /* If .eh_frame is empty, we haven't registered. */
+ if (*(uword *)begin == 0)
+ return ob;
+
init_object_mutex_once ();
__gthread_mutex_lock (&object_mutex);
@@ -235,7 +249,9 @@ __deregister_frame_info (void *begin)
void
__deregister_frame (void *begin)
{
- free (__deregister_frame_info (begin));
+ /* If .eh_frame is empty, we haven't registered. */
+ if (*(uword *)begin != 0)
+ free (__deregister_frame_info (begin));
}
@@ -968,7 +984,7 @@ _Unwind_Find_FDE (void *pc, struct dwarf
__gthread_mutex_lock (&object_mutex);
/* Linear search through the classified objects, to find the one
- containing the pc. Note that pc_begin is sorted decending, and
+ containing the pc. Note that pc_begin is sorted descending, and
we expect objects to be non-overlapping. */
for (ob = seen_objects; ob; ob = ob->next)
if (pc >= ob->pc_begin)
--- libc/sysdeps/generic/unwind-dw2.c 2001/12/27 19:34:14 1.1.1.1
+++ libc/sysdeps/generic/unwind-dw2.c 2001/12/27 21:54:38 1.2
@@ -721,9 +721,9 @@ execute_cfa_program (const unsigned char
_Unwind_Sword offset;
_Unwind_Ptr ptrtmp;
- if (insn & DW_CFA_advance_loc)
+ if ((insn & 0xc0) == DW_CFA_advance_loc)
fs->pc += (insn & 0x3f) * fs->code_align;
- else if (insn & DW_CFA_offset)
+ else if ((insn & 0xc0) == DW_CFA_offset)
{
reg = insn & 0x3f;
insn_ptr = read_uleb128 (insn_ptr, &ptrtmp);
@@ -731,7 +731,7 @@ execute_cfa_program (const unsigned char
fs->regs.reg[reg].how = REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = offset;
}
- else if (insn & DW_CFA_restore)
+ else if ((insn & 0xc0) == DW_CFA_restore)
{
reg = insn & 0x3f;
fs->regs.reg[reg].how = REG_UNSAVED;
Jakub
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