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scx_layered: Make verification easier on older kernels

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Refactor some BPF code to make verification easier on older kernels.
This is to make it easier to maintain backports.

Signed-off-by: Daniel Hodges <hodges.daniel.scott@gmail.com>
This commit is contained in:
Daniel Hodges 2024-08-28 08:03:02 -07:00
parent 5391816853
commit c511b42b7b
2 changed files with 9 additions and 7 deletions
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15
scheds/rust/scx_layered/src/bpf/main.bpf.c
View File

@ -94,7 +94,7 @@ static __noinline u32 iter_layer_cpu_ctx(u32 layer_idx, int idx)
}
// return the dsq id for the layer based on the LLC id.
static inline u64 layer_dsq_id(u32 layer_id, u32 llc_id)
static __noinline u64 layer_dsq_id(u32 layer_id, u32 llc_id)
{
return (layer_id * nr_llcs) + llc_id;
}
@ -862,8 +862,7 @@ void BPF_STRUCT_OPS(layered_dispatch, s32 cpu, struct task_struct *prev)
{
s32 sib = sibling_cpu(cpu);
struct cpu_ctx *cctx, *sib_cctx;
int idx, llc_id;
u32 layer_idx;
u32 idx, llc_id, layer_idx;
u64 dsq_id;
if (!(cctx = lookup_cpu_ctx(-1)))
@ -903,12 +902,12 @@ void BPF_STRUCT_OPS(layered_dispatch, s32 cpu, struct task_struct *prev)
bpf_for(idx, 0, nr_layers) {
layer_idx = iter_layer_cpu_ctx(cctx->layer_idx, idx);
if (disable_topology) {
if (layers[layer_idx].preempt && scx_bpf_consume(layer_idx))
if (MEMBER_VPTR(layers, [layer_idx].preempt) && scx_bpf_consume(layer_idx))
return;
} else {
bpf_for(llc_id, 0, nr_llcs) {
dsq_id = layer_dsq_id(layer_idx, llc_id);
if (layers[layer_idx].preempt && scx_bpf_consume(dsq_id))
if (MEMBER_VPTR(layers, [layer_idx].preempt) && scx_bpf_consume(dsq_id))
return;
}
}
@ -944,7 +943,8 @@ void BPF_STRUCT_OPS(layered_dispatch, s32 cpu, struct task_struct *prev)
return;
if (bpf_cpumask_test_cpu(cpu, layer_cpumask) ||
(cpu == fallback_cpu && layer->nr_cpus == 0)) {
(cpu <= nr_possible_cpus && cpu == fallback_cpu &&
MEMBER_VPTR(layer, ->nr_cpus) == 0)) {
if (scx_bpf_consume(dsq_id))
return;
}
@ -963,7 +963,8 @@ void BPF_STRUCT_OPS(layered_dispatch, s32 cpu, struct task_struct *prev)
bpf_for(llc_id, 0, nr_llcs) {
dsq_id = layer_dsq_id(layer_idx, llc_id);
if (!layers[layer_idx].preempt && layers[layer_idx].open &&
if (!MEMBER_VPTR(layers, [layer_idx].preempt) &&
MEMBER_VPTR(layers, [layer_idx].open) &&
scx_bpf_consume(dsq_id))
return;
}

1
scheds/rust/scx_layered/src/bpf/util.bpf.c
View File

@ -99,6 +99,7 @@ bool __noinline match_prefix(const char *prefix, const char *str, u32 max_len)
}
bpf_for(c, 0, max_len) {
c &= 0xfff;
if (c > len) {
scx_bpf_error("invalid length");
return false; /* appease the verifier */