diff options
| author | Nicolas Pitre <npitre@baylibre.com> | 2025-06-16 15:22:44 -0400 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-07-09 22:57:53 -0700 |
| commit | e795000e755c309d1f9bd2a0590eca38b4625f3a (patch) | |
| tree | 3336ca4b7cd87b4d1843a8d044e9528ad0deee8b /lib/math/div64.c | |
| parent | d71b90e5ba83b32b4e3980f8c07ba2012ad9378a (diff) | |
mul_u64_u64_div_u64: fix the division-by-zero behavior
The current implementation forces a compile-time 1/0 division, which
generates an undefined instruction (ud2 on x86) rather than a proper
runtime division-by-zero exception.
Change to trigger an actual div-by-0 exception at runtime, consistent with
other division operations. Use a non-1 dividend to prevent the compiler
from optimizing the division into a comparison.
Link: https://lkml.kernel.org/r/q246p466-1453-qon9-29so-37105116009q@onlyvoer.pbz
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Cc: Biju Das <biju.das.jz@bp.renesas.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Cc: David Laight <david.laight.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib/math/div64.c')
| -rw-r--r-- | lib/math/div64.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/lib/math/div64.c b/lib/math/div64.c index 5faa29208bdb..bf77b9843175 100644 --- a/lib/math/div64.c +++ b/lib/math/div64.c @@ -212,12 +212,13 @@ u64 mul_u64_u64_div_u64(u64 a, u64 b, u64 c) #endif - /* make sure c is not zero, trigger exception otherwise */ -#pragma GCC diagnostic push -#pragma GCC diagnostic ignored "-Wdiv-by-zero" - if (unlikely(c == 0)) - return 1/0; -#pragma GCC diagnostic pop + /* make sure c is not zero, trigger runtime exception otherwise */ + if (unlikely(c == 0)) { + unsigned long zero = 0; + + OPTIMIZER_HIDE_VAR(zero); + return ~0UL/zero; + } int shift = __builtin_ctzll(c); |