135 lines
4.3 KiB
Plaintext
135 lines
4.3 KiB
Plaintext
v1.19:
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- Support split BTF, where a main BTF file, vmlinux, can be used to find types
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and then a kernel module, for instance, can have just what is unique to it.
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For instance, looking for a type in the main vmlinux BTF info:
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$ pahole wmi_notify_handler
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pahole: type 'wmi_notify_handler' not found
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$
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If we look at the 'wmi' module BTF info that is in:
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$ ls -la /sys/kernel/btf/wmi
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-r--r--r--. 1 root root 2866 Nov 18 13:35 /sys/kernel/btf/wmi
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$
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$ pahole /sys/kernel/btf/wmi -C wmi_notify_handler
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typedef void (*wmi_notify_handler)(u32, void *);
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$
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'--btf_base=/sys/kernel/btf/vmlinux' was automatically added in this last
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example, an option that was also introduced in this version where types used in
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the wmi.ko module but present in vmlinux can be found so that there is no
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duplicity of types.
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- Update libbpf to get the split BTF support and use some of its functions to
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load BTF and speed up DWARF loading and BTF encoding.
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- Support cross-compiled ELF binaries with different endianness
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- Support showing typedefs for anonymous types, like structs, unions and enums,
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see the "Align enumerators" entry below for an example, another:
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$ pahole rwlock_t
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typedef struct {
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arch_rwlock_t raw_lock; /* 0 8 */
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/* size: 8, cachelines: 1, members: 1 */
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/* last cacheline: 8 bytes */
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} rwlock_t;
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$
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- Align enumerators:
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$ pahole ZSTD_strategy
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typedef enum {
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ZSTD_fast = 0,
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ZSTD_dfast = 1,
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ZSTD_greedy = 2,
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ZSTD_lazy = 3,
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ZSTD_lazy2 = 4,
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ZSTD_btlazy2 = 5,
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ZSTD_btopt = 6,
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ZSTD_btopt2 = 7,
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} ZSTD_strategy;
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$
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- Workaround bugs in the generation of DWARF records for functions in some gcc
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versions that were causing breakage in the encoding of BTF:
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97060 "Missing DW_AT_declaration=1 in dwarf data"
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- Ignore zero-sized ELF symbols instead of erroring out.
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- Handle union forward declaration properly in the BTF loader.
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- Introduce --numeric_version for use in scripts and Makefiles:
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$ pahole --version
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v1.19
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$ pahole --numeric_version
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119
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$
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To avoid things like this in the kernel's scripts/link-vmlinux.sh:
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pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
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- Try sole pfunct argument as a function name, just like pahole with type names:
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$ pfunct tcp_v4_rcv
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int tcp_v4_rcv(struct sk_buff * skb);
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$
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- Speed up pfunct using some of the load techniques used in pahole.
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- Discard CUs after BTF encoding as they're not used anymore, greatly reducing
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memory usage and speeding up vmlinux BTF encoding.
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- Revamp how per-CPU variables are encoded in BTF.
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- Include BTF info for static functions.
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- Use BTF's string APIs for strings management, greatly improving performance
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over the tsearch().
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- Increase size of DWARF lookup hash table, shaving off about 1 second out of
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about 20 seconds total for Linux BTF dedup.
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- Stop BTF encoding when errors are found in some DWARF CU.
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- Implement --packed, to show just packed structures, for instance, here are
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the top 5 packed data structures in the Linux kernel:
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$ pahole --sizes --packed | sort -k2 -nr | head -5
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e820_table 64004 0
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boot_params 4096 0
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efi_variable 2084 0
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snd_soc_tplg_pcm 912 0
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ntb_info_regs 800 0
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$
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And here is one of them:
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$ pahole efi_variable
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struct efi_variable {
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efi_char16_t VariableName[512]; /* 0 1024 */
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/* --- cacheline 16 boundary (1024 bytes) --- */
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efi_guid_t VendorGuid; /* 1024 16 */
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long unsigned int DataSize; /* 1040 8 */
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__u8 Data[1024]; /* 1048 1024 */
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/* --- cacheline 32 boundary (2048 bytes) was 24 bytes ago --- */
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efi_status_t Status; /* 2072 8 */
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__u32 Attributes; /* 2080 4 */
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/* size: 2084, cachelines: 33, members: 6 */
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/* last cacheline: 36 bytes */
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} __attribute__((__packed__));
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$
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- Fix bug in distros such as OpenSUSE:15.2 where DW_AT_alignment isn't defined.
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Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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