[RFC,v8,09/20] Define a new dynamic section tag - DT_GNU_FLAGS_1
Commit Message
Define a new flags section DT_GNU_FLAGS_1 (no more bits are available
in DT_GNU_FLAGS).
One flag is currently defined: DF_GNU_1_UNIQUE.
libc and its companion DSOs (libpthread et al) should have this
section and flag set.
---
elf/elf.h | 7 ++++++-
elf/get-dynamic-info.h | 12 ++++++++++++
include/elf.h | 2 ++
include/link.h | 1 +
4 files changed, 21 insertions(+), 1 deletion(-)
Comments
On 09/02/2021 14:18, Vivek Das Mohapatra via Libc-alpha wrote:
> Define a new flags section DT_GNU_FLAGS_1 (no more bits are available
> in DT_GNU_FLAGS).
>
> One flag is currently defined: DF_GNU_1_UNIQUE.
>
> libc and its companion DSOs (libpthread et al) should have this
> section and flag set.
> ---
> elf/elf.h | 7 ++++++-
> elf/get-dynamic-info.h | 12 ++++++++++++
> include/elf.h | 2 ++
> include/link.h | 1 +
> 4 files changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/elf/elf.h b/elf/elf.h
> index 4f838d4af2..9f9b8e4291 100644
> --- a/elf/elf.h
> +++ b/elf/elf.h
> @@ -895,6 +895,7 @@ typedef struct
> Dyn.d_un.d_val field of the Elf*_Dyn structure. This follows Sun's
> approach. */
> #define DT_VALRNGLO 0x6ffffd00
> +#define DT_GNU_FLAGS_1 0x6ffffdf4 /* Open DSO once across all namespaces */
> #define DT_GNU_PRELINKED 0x6ffffdf5 /* Prelinking timestamp */
> #define DT_GNU_CONFLICTSZ 0x6ffffdf6 /* Size of conflict section */
> #define DT_GNU_LIBLISTSZ 0x6ffffdf7 /* Size of library list */
Ok, it matches binutils definition.
> @@ -909,7 +910,7 @@ typedef struct
> #define DT_SYMINENT 0x6ffffdff /* Entry size of syminfo */
> #define DT_VALRNGHI 0x6ffffdff
> #define DT_VALTAGIDX(tag) (DT_VALRNGHI - (tag)) /* Reverse order! */
> -#define DT_VALNUM 12
> +#define DT_VALNUM 13
>
Ok.
> /* DT_* entries which fall between DT_ADDRRNGHI & DT_ADDRRNGLO use the
> Dyn.d_un.d_ptr field of the Elf*_Dyn structure.
> @@ -998,6 +999,10 @@ typedef struct
> #define DF_1_WEAKFILTER 0x20000000
> #define DF_1_NOCOMMON 0x40000000
>
> +/* State flags selectable in the `d_un.d_val' element of the DT_GNU_FLAGS_1
> + entry in the dynamic section. */
> +#define DF_GNU_1_UNIQUE 0x00000001
> +
> /* Flags for the feature selection in DT_FEATURE_1. */
> #define DTF_1_PARINIT 0x00000001
> #define DTF_1_CONFEXP 0x00000002
Ok, it matches binutils definition.
> diff --git a/elf/get-dynamic-info.h b/elf/get-dynamic-info.h
> index d8ec32377d..d441b39576 100644
> --- a/elf/get-dynamic-info.h
> +++ b/elf/get-dynamic-info.h
> @@ -175,6 +175,18 @@ elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp)
> if (l->l_flags_1 & DF_1_NOW)
> info[DT_BIND_NOW] = info[VERSYMIDX (DT_FLAGS_1)];
> }
> + if (info[DT_VALTAGIDX (DT_GNU_FLAGS_1)
> + + DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM + DT_EXTRANUM] != NULL)
> + {
> + l->l_gnu_flags_1 = info[DT_VALTAGIDX (DT_GNU_FLAGS_1)
> + + DT_NUM + DT_THISPROCNUM
> + + DT_VERSIONTAGNUM + DT_EXTRANUM]->d_un.d_val;
> +
> + if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0)
> + && l->l_gnu_flags_1 & ~DT_GNU_1_SUPPORTED_MASK)
Use __glibc_likely.
> + _dl_debug_printf ("\nWARNING: Unsupported flag value(s) of 0x%x in DT_GNU_FLAGS_1.\n",
> + l->l_gnu_flags_1 & ~DT_GNU_1_SUPPORTED_MASK);
> + }
> if (info[DT_RUNPATH] != NULL)
> /* If both RUNPATH and RPATH are given, the latter is ignored. */
> info[DT_RPATH] = NULL;
Ok.
> diff --git a/include/elf.h b/include/elf.h
> index 14ed67ff67..5eee37c294 100644
> --- a/include/elf.h
> +++ b/include/elf.h
> @@ -25,5 +25,7 @@
> (DF_1_NOW | DF_1_NODELETE | DF_1_INITFIRST | DF_1_NOOPEN \
> | DF_1_ORIGIN | DF_1_NODEFLIB | DF_1_PIE)
>
> +#define DT_GNU_1_SUPPORTED_MASK DF_GNU_1_UNIQUE
> +
> #endif /* !_ISOMAC */
> #endif /* elf.h */
Ok.
> diff --git a/include/link.h b/include/link.h
> index b51fa0cbdf..55e0cad71d 100644
> --- a/include/link.h
> +++ b/include/link.h
> @@ -285,6 +285,7 @@ struct link_map
> unsigned int l_used;
>
> /* Various flag words. */
> + ElfW(Word) l_gnu_flags_1;
> ElfW(Word) l_feature_1;
> ElfW(Word) l_flags_1;
> ElfW(Word) l_flags;
>
Ok.
@@ -895,6 +895,7 @@ typedef struct
Dyn.d_un.d_val field of the Elf*_Dyn structure. This follows Sun's
approach. */
#define DT_VALRNGLO 0x6ffffd00
+#define DT_GNU_FLAGS_1 0x6ffffdf4 /* Open DSO once across all namespaces */
#define DT_GNU_PRELINKED 0x6ffffdf5 /* Prelinking timestamp */
#define DT_GNU_CONFLICTSZ 0x6ffffdf6 /* Size of conflict section */
#define DT_GNU_LIBLISTSZ 0x6ffffdf7 /* Size of library list */
@@ -909,7 +910,7 @@ typedef struct
#define DT_SYMINENT 0x6ffffdff /* Entry size of syminfo */
#define DT_VALRNGHI 0x6ffffdff
#define DT_VALTAGIDX(tag) (DT_VALRNGHI - (tag)) /* Reverse order! */
-#define DT_VALNUM 12
+#define DT_VALNUM 13
/* DT_* entries which fall between DT_ADDRRNGHI & DT_ADDRRNGLO use the
Dyn.d_un.d_ptr field of the Elf*_Dyn structure.
@@ -998,6 +999,10 @@ typedef struct
#define DF_1_WEAKFILTER 0x20000000
#define DF_1_NOCOMMON 0x40000000
+/* State flags selectable in the `d_un.d_val' element of the DT_GNU_FLAGS_1
+ entry in the dynamic section. */
+#define DF_GNU_1_UNIQUE 0x00000001
+
/* Flags for the feature selection in DT_FEATURE_1. */
#define DTF_1_PARINIT 0x00000001
#define DTF_1_CONFEXP 0x00000002
@@ -175,6 +175,18 @@ elf_get_dynamic_info (struct link_map *l, ElfW(Dyn) *temp)
if (l->l_flags_1 & DF_1_NOW)
info[DT_BIND_NOW] = info[VERSYMIDX (DT_FLAGS_1)];
}
+ if (info[DT_VALTAGIDX (DT_GNU_FLAGS_1)
+ + DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM + DT_EXTRANUM] != NULL)
+ {
+ l->l_gnu_flags_1 = info[DT_VALTAGIDX (DT_GNU_FLAGS_1)
+ + DT_NUM + DT_THISPROCNUM
+ + DT_VERSIONTAGNUM + DT_EXTRANUM]->d_un.d_val;
+
+ if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0)
+ && l->l_gnu_flags_1 & ~DT_GNU_1_SUPPORTED_MASK)
+ _dl_debug_printf ("\nWARNING: Unsupported flag value(s) of 0x%x in DT_GNU_FLAGS_1.\n",
+ l->l_gnu_flags_1 & ~DT_GNU_1_SUPPORTED_MASK);
+ }
if (info[DT_RUNPATH] != NULL)
/* If both RUNPATH and RPATH are given, the latter is ignored. */
info[DT_RPATH] = NULL;
@@ -25,5 +25,7 @@
(DF_1_NOW | DF_1_NODELETE | DF_1_INITFIRST | DF_1_NOOPEN \
| DF_1_ORIGIN | DF_1_NODEFLIB | DF_1_PIE)
+#define DT_GNU_1_SUPPORTED_MASK DF_GNU_1_UNIQUE
+
#endif /* !_ISOMAC */
#endif /* elf.h */
@@ -285,6 +285,7 @@ struct link_map
unsigned int l_used;
/* Various flag words. */
+ ElfW(Word) l_gnu_flags_1;
ElfW(Word) l_feature_1;
ElfW(Word) l_flags_1;
ElfW(Word) l_flags;