On Tue, 2025-06-17 at 19:17 -0400, Harishankar Vishwanathan wrote:
The previous commit improves the precision in scalar(32)_min_max_add, and scalar(32)_min_max_sub. The improvement in precision occurs in cases when all outcomes overflow or underflow, respectively. This commit adds selftests that exercise those cases.
Co-developed-by: Matan Shachnai m.shachnai@rutgers.edu Signed-off-by: Matan Shachnai m.shachnai@rutgers.edu Signed-off-by: Harishankar Vishwanathan harishankar.vishwanathan@gmail.com
Could you please also add test cases when one bound overflows while another does not? Or these are covered by some other tests?
[...]
+SEC("socket") +__description("64-bit addition overflow, all outcomes overflow") +__success __log_level(2) +__msg("7: (0f) r5 += r3 {{.*}} R5_w=scalar(smin=0x800003d67e960f7d,umin=0x551ee3d67e960f7d,umax=0xc0149fffffffffff,smin32=0xfe960f7d,umin32=0x7e960f7d,var_off=(0x3d67e960f7d; 0xfffffc298169f082))")
Would it be possible to pick some more "human readable" constants here? As-is it is hard to make sense what verifier actually computes.
+__retval(0) +__naked void add64_ovf(void) +{
- asm volatile (
- "call %[bpf_get_prandom_u32];"
- "r3 = r0;"
- "r4 = 0x950a43d67e960f7d ll;"
- "r3 |= r4;"
- "r5 = 0xc014a00000000000 ll;"
- "r5 += r3;"
- "r0 = 0;"
- "exit"
- :
- : __imm(bpf_get_prandom_u32)
- : __clobber_all);
+}
[...]