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authorWill Deacon <will@kernel.org>2019-11-21 14:58:58 +0300
committerIngo Molnar <mingo@kernel.org>2019-11-25 11:15:21 +0300
commit1eb085d94256aaa69b00cf5a86e3c5f5bb2bc460 (patch)
tree33510b14c7d093cbedf09d156e8dc6899004846d /lib/refcount.c
parentdcb786493f3e48da3272b710028d42ec608cfda1 (diff)
downloadlinux-1eb085d94256aaa69b00cf5a86e3c5f5bb2bc460.tar.xz
locking/refcount: Move saturation warnings out of line
Having the refcount saturation and warnings inline bloats the text, despite the fact that these paths should never be executed in normal operation. Move the refcount saturation and warnings out of line to reduce the image size when refcount_t checking is enabled. Relative to an x86_64 defconfig, the sizes reported by bloat-o-meter are: # defconfig+REFCOUNT_FULL, inline saturation (i.e. before this patch) Total: Before=14762076, After=14915442, chg +1.04% # defconfig+REFCOUNT_FULL, out-of-line saturation (i.e. after this patch) Total: Before=14762076, After=14835497, chg +0.50% A side-effect of this change is that we now only get one warning per refcount saturation type, rather than one per problematic call-site. Signed-off-by: Will Deacon <will@kernel.org> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Hanjun Guo <guohanjun@huawei.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Elena Reshetova <elena.reshetova@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20191121115902.2551-7-will@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'lib/refcount.c')
-rw-r--r--lib/refcount.c28
1 files changed, 28 insertions, 0 deletions
diff --git a/lib/refcount.c b/lib/refcount.c
index 3a534fbebdcc..8b7e249c0e10 100644
--- a/lib/refcount.c
+++ b/lib/refcount.c
@@ -8,6 +8,34 @@
#include <linux/spinlock.h>
#include <linux/bug.h>
+#define REFCOUNT_WARN(str) WARN_ONCE(1, "refcount_t: " str ".\n")
+
+void refcount_warn_saturate(refcount_t *r, enum refcount_saturation_type t)
+{
+ refcount_set(r, REFCOUNT_SATURATED);
+
+ switch (t) {
+ case REFCOUNT_ADD_NOT_ZERO_OVF:
+ REFCOUNT_WARN("saturated; leaking memory");
+ break;
+ case REFCOUNT_ADD_OVF:
+ REFCOUNT_WARN("saturated; leaking memory");
+ break;
+ case REFCOUNT_ADD_UAF:
+ REFCOUNT_WARN("addition on 0; use-after-free");
+ break;
+ case REFCOUNT_SUB_UAF:
+ REFCOUNT_WARN("underflow; use-after-free");
+ break;
+ case REFCOUNT_DEC_LEAK:
+ REFCOUNT_WARN("decrement hit 0; leaking memory");
+ break;
+ default:
+ REFCOUNT_WARN("unknown saturation event!?");
+ }
+}
+EXPORT_SYMBOL(refcount_warn_saturate);
+
/**
* refcount_dec_if_one - decrement a refcount if it is 1
* @r: the refcount