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scx_lavd: fix/work around a verifier error

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Without this, the BPF verifier spits the following errors
with *some* version of vmlinux.h. So added +1 to work around
the problem.

---------------
; bpf_for(j, 0, 64) { @ main.bpf.c:1926
509: (bf) r1 = r8                     ; R1_w=fp-32 R8_w=fp-32 refs=66,2035
510: (b4) w2 = 0                      ; R2_w=0 refs=66,2035
511: (b4) w3 = 64                     ; R3_w=64 refs=66,2035
512: (85) call bpf_iter_num_new#104189        ; R0=scalar() fp-32=iter_num(ref_id=2048,state=active,depth=0) refs=66,2035,2048
513: (bf) r1 = r8                     ; R1=fp-32 R8=fp-32 refs=66,2035,2048
514: (85) call bpf_iter_num_next#104191 515: R0_w=rdonly_mem(id=2049,ref_obj_id=2048,sz=4) R6=scalar(id=2047,smin=smin32=0,smax=umax=smax32=umax32=7,var_off=(0x0; 0x7)) R7=scalar() R8=fp-32 R9=map_value(map=bpf_bpf.bss,ks=4,vs=4584,off=384,smin=smin32=0,smax=umax=smax32=umax32=3968,var_off=(0x0; 0xf80)) R10=fp0 fp-16=iter_num(ref_id=66,state=active,depth=1) fp-24=iter_num(ref_id=2035,state=active,depth=1) fp-32=iter_num(ref_id=2048,state=active,depth=1) fp-80=scalar(id=1) fp-88=map_value(map=.data.LAVD,ks=4,vs=1320,off=40,smin=smin32=0,smax=umax=smax32=umax32=1240,var_off=(0x0; 0x7f8)) fp-96=????0 fp-112=rcu_ptr_bpf_cpumask() fp-120=rcu_ptr_bpf_cpumask() fp-128=rcu_ptr_bpf_cpumask() fp-136=rcu_ptr_bpf_cpumask() refs=66,2035,2048
; bpf_for(j, 0, 64) { @ main.bpf.c:1926
515: (15) if r0 == 0x0 goto pc+49     ; R0_w=rdonly_mem(id=2049,ref_obj_id=2048,sz=4) refs=66,2035,2048
516: (64) w6 <<= 6                    ; R6=scalar(smin=smin32=0,smax=umax=smax32=umax32=448,var_off=(0x0; 0x1c0)) refs=66,2035,2048
517: (61) r8 = *(u32 *)(r0 +0)        ; R0=rdonly_mem(id=2049,ref_obj_id=2048,sz=4) R8_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff)) refs=66,2035,2048
518: (26) if w8 > 0x3f goto pc+46     ; R8_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=63,var_off=(0x0; 0x3f)) refs=66,2035,2048
; if (cpumask & 0x1LLU << j) { @ main.bpf.c:1927
519: (bf) r1 = r7                     ; R1_w=scalar(id=2053) R7=scalar(id=2053) refs=66,2035,2048
520: (7f) r1 >>= r8                   ; R1_w=scalar() R8_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=63,var_off=(0x0; 0x3f)) refs=66,2035,2048
521: (57) r1 &= 1                     ; R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1,var_off=(0x0; 0x1)) refs=66,2035,2048
522: (15) if r1 == 0x0 goto pc+38     ; R1_w=1 refs=66,2035,2048
; cpu = (i * 64) + j; @ main.bpf.c:1928
523: (4c) w8 |= w6                    ; R6=scalar(smin=smin32=0,smax=umax=smax32=umax32=448,var_off=(0x0; 0x1c0)) R8_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=511,var_off=(0x0; 0x1ff)) refs=66,2035,2048
; bpf_cpumask_set_cpu(cpu, cd_cpumask); @ main.bpf.c:1929
524: (bc) w1 = w8                     ; R1_w=scalar(id=2054,smin=smin32=0,smax=umax=smax32=umax32=511,var_off=(0x0; 0x1ff)) R8_w=scalar(id=2054,smin=smin32=0,smax=umax=smax32=umax32=511,var_off=(0x0; 0x1ff)) refs=66,2035,2048
525: (79) r2 = *(u64 *)(r10 -88)      ; R2_w=map_value(map=.data.LAVD,ks=4,vs=1320,off=40,smin=smin32=0,smax=umax=smax32=umax32=1240,var_off=(0x0; 0x7f8)) R10=fp0 fp-88=map_value(map=.data.LAVD,ks=4,vs=1320,off=40,smin=smin32=0,smax=umax=smax32=umax32=1240,var_off=(0x0; 0x7f8)) refs=66,2035,2048
526: (85) call bpf_cpumask_set_cpu#93595
invalid access to map value, value_size=1320 off=1280 size=48
R2 max value is outside of the allowed memory range
processed 24200 insns (limit 1000000) max_states_per_insn 19 total_states 961 peak_states 789 mark_read 44
---------------

Signed-off-by: Changwoo Min <changwoo@igalia.com>
This commit is contained in:
Changwoo Min 2024-10-22 17:19:37 +09:00
parent d5b8aafa1a
commit 89749ecad7
1 changed files with 5 additions and 1 deletions
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6
scheds/rust/scx_lavd/src/bpf/util.bpf.c
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@ -16,7 +16,11 @@ private(LAVD) struct bpf_cpumask __kptr *big_cpumask; /* CPU mask for big CPUs *
private(LAVD) struct bpf_cpumask __kptr *little_cpumask; /* CPU mask for little CPUs */ private(LAVD) struct bpf_cpumask __kptr *little_cpumask; /* CPU mask for little CPUs */
private(LAVD) struct bpf_cpumask __kptr *active_cpumask; /* CPU mask for active CPUs */ private(LAVD) struct bpf_cpumask __kptr *active_cpumask; /* CPU mask for active CPUs */
private(LAVD) struct bpf_cpumask __kptr *ovrflw_cpumask; /* CPU mask for overflow CPUs */ private(LAVD) struct bpf_cpumask __kptr *ovrflw_cpumask; /* CPU mask for overflow CPUs */
private(LAVD) struct bpf_cpumask cpdom_cpumask[LAVD_CPDOM_MAX_NR]; /* CPU mask for each compute domain */ private(LAVD) struct bpf_cpumask cpdom_cpumask[LAVD_CPDOM_MAX_NR+1]; /* CPU mask for each compute domain */
/*
* I am sure that +1 shouldn't be necessary here.
* But it is added to workaround a verifier bug (?).
*/
const volatile u64 nr_cpu_ids; /* maximum CPU IDs */ const volatile u64 nr_cpu_ids; /* maximum CPU IDs */
static volatile u64 nr_cpus_onln; /* current number of online CPUs */ static volatile u64 nr_cpus_onln; /* current number of online CPUs */