diff options
| -rw-r--r-- | NEWS | 5 | ||||
| -rw-r--r-- | elf/Makefile | 2 | ||||
| -rw-r--r-- | elf/dl-tunables.list | 5 | ||||
| -rw-r--r-- | manual/tunables.texi | 17 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/setvmaname.c | 15 |
5 files changed, 38 insertions, 6 deletions
diff --git a/NEWS b/NEWS index 4580fe381d..139cfef1b0 100644 --- a/NEWS +++ b/NEWS @@ -38,6 +38,11 @@ Major new features: and the wfN format length modifiers for arguments pointing to types int_fastN_t or uint_fastN_t, as specified in draft ISO C2X. +* A new tunable, glibc.mem.decorate_maps, can be used to add additional + information on underlying memory allocated by the glibc (for instance, + on thread stack created by pthread_create or memory allocated by + malloc). + Deprecated and removed features, and other changes affecting compatibility: * The ldconfig program now skips file names containing ';' or ending in diff --git a/elf/Makefile b/elf/Makefile index 328dbe82de..f9bd86a05a 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -2985,5 +2985,5 @@ $(objpfx)tst-dlclose-lazy.out: \ $(objpfx)tst-decorate-maps: $(shared-thread-library) tst-decorate-maps-ENV = \ - GLIBC_TUNABLES=glibc.malloc.arena_max=8:glibc.malloc.mmap_threshold=1024 + GLIBC_TUNABLES=glibc.malloc.arena_max=8:glibc.malloc.mmap_threshold=1024:glibc.mem.decorate_maps=1 tst-decorate-maps-ARGS = 8 diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list index 695ba7192e..888d2ede04 100644 --- a/elf/dl-tunables.list +++ b/elf/dl-tunables.list @@ -160,6 +160,11 @@ glibc { maxval: 255 security_level: SXID_IGNORE } + decorate_maps { + type: INT_32 + minval: 0 + maxval: 1 + } } rtld { diff --git a/manual/tunables.texi b/manual/tunables.texi index 776fd93fd9..c28360adcd 100644 --- a/manual/tunables.texi +++ b/manual/tunables.texi @@ -653,6 +653,23 @@ support in the kernel if this tunable has any non-zero value. The default value is @samp{0}, which disables all memory tagging. @end deftp +@deftp Tunable glibc.mem.decorate_maps +If the kernel supports naming anonymous virtual memory areas (since +Linux version 5.17, although not always enabled by some kernel +configurations), this tunable can be used to control whether +@theglibc{} decorates the underlying memory obtained from operating +system with a string describing its usage (for instance, on the thread +stack created by @code{ptthread_create} or memory allocated by +@code{malloc}). + +The process mappings can be obtained by reading the @code{/proc/<pid>maps} +(with @code{pid} being either the @dfn{process ID} or @code{self} for the +process own mapping). + +This tunable takes a value of 0 and 1, where 1 enables the feature. +The default value is @samp{0}, which disables the decoration. +@end deftp + @node gmon Tunables @section gmon Tunables @cindex gmon tunables diff --git a/sysdeps/unix/sysv/linux/setvmaname.c b/sysdeps/unix/sysv/linux/setvmaname.c index 9960ab5917..cd6d571772 100644 --- a/sysdeps/unix/sysv/linux/setvmaname.c +++ b/sysdeps/unix/sysv/linux/setvmaname.c @@ -20,6 +20,7 @@ #include <setvmaname.h> #include <sys/prctl.h> #include <sysdep.h> +#include <elf/dl-tunables.h> /* If PR_SET_VMA_ANON_NAME is not supported by the kernel, prctl returns EINVAL. However, it also returns the same error for invalid argument. @@ -34,11 +35,15 @@ __set_vma_name (void *start, size_t len, const char *name) if (atomic_load_relaxed (&prctl_supported) == 0) return; - int r = INTERNAL_SYSCALL_CALL (prctl, PR_SET_VMA, PR_SET_VMA_ANON_NAME, - start, len, name); - if (r == 0 || r != -EINVAL) - return; - + /* Set the prctl as not supported to avoid checking the tunable on every + call. */ + if (TUNABLE_GET (glibc, mem, decorate_maps, int32_t, NULL) != 0) + { + int r = INTERNAL_SYSCALL_CALL (prctl, PR_SET_VMA, PR_SET_VMA_ANON_NAME, + start, len, name); + if (r == 0 || r != -EINVAL) + return; + } atomic_store_relaxed (&prctl_supported, 0); return; } |