From 27600805e62f800bacf990354632eae4e487d34c Mon Sep 17 00:00:00 2001 From: Yazen Ghannam Date: Thu, 3 Sep 2026 10:43:25 -0500 Subject: x86/amd_node: Fix PCI device reference counting in amd_smn_init() The local "root" pointer is a temporary variable used during the device search. Therefore, refcount related to the search iterators should be cleaned up after the search is complete. Use the __free() cleanup macro to ensure the refcount is decremented when the temporary pointer goes out of scope. Additionally, increment the refcount when caching a root pointer. This ensures the in-use refcount is separate from the temporary search refcounting. Finally, drop the redundant "root = NULL" before the second search loop. The pci_get_class() iterator always decrements the refcount of its "from" argument, so the first loop can only fall through with "root" already NULL. Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching") Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com Reported-by: Sashiko Assisted-by: LLM Signed-off-by: Yazen Ghannam Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Mario Limonciello (AMD) Cc: Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com --- samples/bpf/tracex6.bpf.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 samples/bpf/tracex6.bpf.c (limited to 'samples/bpf/tracex6.bpf.c') diff --git a/samples/bpf/tracex6.bpf.c b/samples/bpf/tracex6.bpf.c new file mode 100644 index 000000000..9b23b4737 --- /dev/null +++ b/samples/bpf/tracex6.bpf.c @@ -0,0 +1,81 @@ +#include "vmlinux.h" +#include +#include +#include +#include + +struct { + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY); + __uint(key_size, sizeof(int)); + __uint(value_size, sizeof(u32)); + __uint(max_entries, 64); +} counters SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __type(key, int); + __type(value, u64); + __uint(max_entries, 64); +} values SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __type(key, int); + __type(value, struct bpf_perf_event_value); + __uint(max_entries, 64); +} values2 SEC(".maps"); + +SEC("kprobe/htab_map_get_next_key") +int bpf_prog1(struct pt_regs *ctx) +{ + u32 key = bpf_get_smp_processor_id(); + u64 count, *val; + s64 error; + + count = bpf_perf_event_read(&counters, key); + error = (s64)count; + if (error <= -2 && error >= -22) + return 0; + + val = bpf_map_lookup_elem(&values, &key); + if (val) + *val = count; + else + bpf_map_update_elem(&values, &key, &count, BPF_NOEXIST); + + return 0; +} + +/* + * Since *_map_lookup_elem can't be expected to trigger bpf programs + * due to potential deadlocks (bpf_disable_instrumentation), this bpf + * program will be attached to bpf_map_copy_value (which is called + * from map_lookup_elem) and will only filter the hashtable type. + */ +SEC("kprobe/bpf_map_copy_value") +int BPF_KPROBE(bpf_prog2, struct bpf_map *map) +{ + u32 key = bpf_get_smp_processor_id(); + struct bpf_perf_event_value *val, buf; + enum bpf_map_type type; + int error; + + type = BPF_CORE_READ(map, map_type); + if (type != BPF_MAP_TYPE_HASH) + return 0; + + error = bpf_perf_event_read_value(&counters, key, &buf, sizeof(buf)); + if (error) + return 0; + + val = bpf_map_lookup_elem(&values2, &key); + if (val) + *val = buf; + else + bpf_map_update_elem(&values2, &key, &buf, BPF_NOEXIST); + + return 0; +} + +char _license[] SEC("license") = "GPL"; +u32 _version SEC("version") = LINUX_VERSION_CODE; -- cgit v1.3.1