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| author | Will Deacon <will@kernel.org> | 2019-11-21 11:58:58 +0000 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-11-25 09:15:21 +0100 |
| commit | 1eb085d94256aaa69b00cf5a86e3c5f5bb2bc460 (patch) | |
| tree | 33510b14c7d093cbedf09d156e8dc6899004846d /lib/refcount.c | |
| parent | dcb786493f3e48da3272b710028d42ec608cfda1 (diff) | |
| download | lwn-1eb085d94256aaa69b00cf5a86e3c5f5bb2bc460.tar.gz lwn-1eb085d94256aaa69b00cf5a86e3c5f5bb2bc460.zip | |
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.c | 28 |
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 |