diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/setvmaname.c')
| -rw-r--r-- | sysdeps/unix/sysv/linux/setvmaname.c | 45 |
1 files changed, 33 insertions, 12 deletions
diff --git a/sysdeps/unix/sysv/linux/setvmaname.c b/sysdeps/unix/sysv/linux/setvmaname.c index 749c587..ea93a5f 100644 --- a/sysdeps/unix/sysv/linux/setvmaname.c +++ b/sysdeps/unix/sysv/linux/setvmaname.c @@ -22,6 +22,33 @@ #include <sysdep.h> #include <elf/dl-tunables.h> +static enum { + decorate_unknown = -1, + decorate_off, + decorate_on +} decorate_maps = decorate_unknown; + +bool +__is_decorate_maps_enabled (void) +{ + switch (atomic_load_relaxed (&decorate_maps)) + { + case decorate_unknown: + if (TUNABLE_GET (glibc, mem, decorate_maps, int32_t, NULL) != 0) + { + atomic_store_relaxed (&decorate_maps, decorate_on); + return true; + } + atomic_store_relaxed (&decorate_maps, decorate_off); + return false; + case decorate_off: + return false; + case decorate_on: + return true; + } + __builtin_unreachable (); +} + /* 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. Since it is an internal-only API, it assumes well formatted input: @@ -31,19 +58,13 @@ void __set_vma_name (void *start, size_t len, const char *name) { - static int prctl_supported = 1; - if (atomic_load_relaxed (&prctl_supported) == 0) - 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) + if (__is_decorate_maps_enabled ()) { int r = INTERNAL_SYSCALL_CALL (prctl, PR_SET_VMA, PR_SET_VMA_ANON_NAME, - start, len, name); - if (r == 0 || r != -EINVAL) - return; + start, len, name); + + /* Disable further attempts if not supported by the kernel. */ + if (r == -EINVAL) + atomic_store_relaxed (&decorate_maps, decorate_off); } - atomic_store_relaxed (&prctl_supported, 0); - return; } |