forked from OSchip/llvm-project
[llvm-readobj] - Add a few warnings for --gnu-hash-table.
The current implementation stops dumping in case of a single error it handles, though we can continue dumping. This patch refines it: it adds a few warnings and a few test cases. Differential revision: https://reviews.llvm.org/D73269
This commit is contained in:
Georgii Rymar
parent
7fd7a9a636
commit
5f8e51a9d4
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@ -100,3 +100,217 @@ ProgramHeaders:
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Sections:
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- Section: .gnu.hash
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- Section: .dynamic
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## Check we report a warning if there is no dynamic symbol section in the object.
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# RUN: yaml2obj --docnum=3 %s -o %t.nodynsym
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# RUN: llvm-readobj --gnu-hash-table %t.nodynsym 2>&1 | FileCheck %s -DFILE=%t.nodynsym --check-prefix=NODYNSYM
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# RUN: llvm-readelf --gnu-hash-table %t.nodynsym 2>&1 | FileCheck %s -DFILE=%t.nodynsym --check-prefix=NODYNSYM
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# NODYNSYM: GnuHashTable {
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# NODYNSYM-NEXT: Num Buckets: 1
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# NODYNSYM-NEXT: First Hashed Symbol Index: 0
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# NODYNSYM-NEXT: Num Mask Words: 1
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# NODYNSYM-NEXT: Shift Count: 0
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# NODYNSYM-NEXT: Bloom Filter: [0x0]
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# NODYNSYM-NEXT: Buckets: [0]
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# NODYNSYM-NEXT: warning: '[[FILE]]': unable to dump 'Values' for the SHT_GNU_HASH section: no dynamic symbol table found
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# NODYNSYM-NEXT: }
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--- !ELF
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FileHeader:
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Class: ELFCLASS64
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Data: ELFDATA2LSB
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Type: ET_DYN
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Machine: EM_X86_64
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Sections:
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- Name: .gnu.hash
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Type: SHT_GNU_HASH
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Flags: [ SHF_ALLOC ]
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Header:
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SymNdx: 0x0
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Shift2: 0x0
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BloomFilter: [ 0x0 ]
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HashBuckets: [ 0x0 ]
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HashValues: [ 0x0 ]
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- Name: .dynamic
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Type: SHT_DYNAMIC
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Flags: [ SHF_ALLOC ]
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Entries:
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- Tag: DT_GNU_HASH
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Value: 0x0
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- Tag: DT_NULL
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Value: 0x0
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ProgramHeaders:
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- Type: PT_LOAD
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Flags: [ PF_R, PF_X ]
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Sections:
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- Section: .gnu.hash
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- Section: .dynamic
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## Check what we do when the index of the first symbol in the dynamic symbol table
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## included in the hash table is larger than the number of dynamic symbols.
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# RUN: yaml2obj --docnum=4 %s -o %t.brokensymndx
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# RUN: llvm-readobj --gnu-hash-table %t.brokensymndx 2>&1 \
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# RUN: | FileCheck %s -DFILE=%t.brokensymndx --check-prefix=SYMNDX
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# RUN: llvm-readelf --gnu-hash-table %t.brokensymndx 2>&1 \
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# RUN: | FileCheck %s -DFILE=%t.brokensymndx --check-prefix=SYMNDX
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# SYMNDX: GnuHashTable {
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# SYMNDX-NEXT: Num Buckets: 1
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# SYMNDX-NEXT: First Hashed Symbol Index: 2
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# SYMNDX-NEXT: Num Mask Words: 1
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# SYMNDX-NEXT: Shift Count: 0
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# SYMNDX-NEXT: Bloom Filter: [0x1]
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# SYMNDX-NEXT: Buckets: [2]
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# SYMNDX-NEXT: warning: '[[FILE]]': the first hashed symbol index (2) is larger than the number of dynamic symbols (2)
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# SYMNDX-NEXT: }
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--- !ELF
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FileHeader:
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Class: ELFCLASS64
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Data: ELFDATA2LSB
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Type: ET_DYN
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Machine: EM_X86_64
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Sections:
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- Name: .gnu.hash
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Type: SHT_GNU_HASH
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Flags: [ SHF_ALLOC ]
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Header:
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SymNdx: 0x2
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Shift2: 0x0
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BloomFilter: [ 0x1 ]
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HashBuckets: [ 0x2 ]
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HashValues: [ 0x3 ]
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- Name: .dynamic
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Type: SHT_DYNAMIC
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Flags: [ SHF_ALLOC ]
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Link: 0
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Entries:
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- Tag: DT_GNU_HASH
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Value: 0x0
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- Tag: DT_NULL
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Value: 0x0
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DynamicSymbols:
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- Name: aaa
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Binding: STB_GLOBAL
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ProgramHeaders:
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- Type: PT_LOAD
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Flags: [ PF_R, PF_X ]
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Sections:
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- Section: .gnu.hash
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- Section: .dynamic
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## Check we emit a warning when the dynamic symbol table is empty.
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## A valid dynamic symbol table should have at least one symbol: the symbol with index 0.
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# RUN: yaml2obj --docnum=5 %s -o %t.emptydynsym
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# RUN: llvm-readobj --gnu-hash-table %t.emptydynsym 2>&1 \
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# RUN: | FileCheck %s -DFILE=%t.emptydynsym --check-prefix=EMPTY-DYNSYM
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# RUN: llvm-readelf --gnu-hash-table %t.emptydynsym 2>&1 \
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# RUN: | FileCheck %s -DFILE=%t.emptydynsym --check-prefix=EMPTY-DYNSYM
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# EMPTY-DYNSYM: GnuHashTable {
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# EMPTY-DYNSYM-NEXT: Num Buckets: 1
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# EMPTY-DYNSYM-NEXT: First Hashed Symbol Index: 0
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# EMPTY-DYNSYM-NEXT: Num Mask Words: 1
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# EMPTY-DYNSYM-NEXT: Shift Count: 0
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# EMPTY-DYNSYM-NEXT: Bloom Filter: [0x0]
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# EMPTY-DYNSYM-NEXT: Buckets: [0]
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# EMPTY-DYNSYM-NEXT: warning: '[[FILE]]': unable to dump 'Values' for the SHT_GNU_HASH section: the dynamic symbol table is empty
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# EMPTY-DYNSYM-NEXT: }
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--- !ELF
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FileHeader:
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Class: ELFCLASS64
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Data: ELFDATA2LSB
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Type: ET_DYN
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Machine: EM_X86_64
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Sections:
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- Name: .gnu.hash
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Type: SHT_GNU_HASH
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Flags: [ SHF_ALLOC ]
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Header:
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SymNdx: 0x0
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Shift2: 0x0
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BloomFilter: [ 0x0 ]
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HashBuckets: [ 0x0 ]
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HashValues: [ 0x0 ]
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- Name: .dynamic
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Type: SHT_DYNAMIC
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Flags: [ SHF_ALLOC ]
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Link: 0
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Entries:
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- Tag: DT_GNU_HASH
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Value: 0x0
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- Tag: DT_NULL
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Value: 0x0
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- Name: .dynsym
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Type: SHT_DYNSYM
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Size: 0
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ProgramHeaders:
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- Type: PT_LOAD
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Flags: [ PF_R, PF_X ]
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Sections:
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- Section: .gnu.hash
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- Section: .dynamic
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## Linkers might produce an empty no-op SHT_GNU_HASH section when
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## there are no dynamic symbols or when all dynamic symbols are undefined.
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## Such sections normally have a single zero entry in the bloom
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## filter, a single zero entry in the hash bucket and no values.
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##
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## The index of the first symbol in the dynamic symbol table
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## included in the hash table can be set to the number of dynamic symbols,
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## which is one larger than the index of the last dynamic symbol.
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## For empty tables however, this value is unimportant and can be ignored.
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# RUN: yaml2obj --docnum=6 %s -o %t.empty
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# RUN: llvm-readobj --gnu-hash-table %t.empty 2>&1 \
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# RUN: | FileCheck %s -DFILE=%t.empty --check-prefix=EMPTY --implicit-check-not="warning:"
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# RUN: llvm-readelf --gnu-hash-table %t.empty 2>&1 \
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# RUN: | FileCheck %s -DFILE=%t.empty --check-prefix=EMPTY --implicit-check-not="warning:"
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# EMPTY: GnuHashTable {
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# EMPTY-NEXT: Num Buckets: 1
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# EMPTY-NEXT: First Hashed Symbol Index: 1
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# EMPTY-NEXT: Num Mask Words: 1
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# EMPTY-NEXT: Shift Count: 0
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# EMPTY-NEXT: Bloom Filter: [0x0]
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# EMPTY-NEXT: Buckets: [0]
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# EMPTY-NEXT: Values: []
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# EMPTY-NEXT: }
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--- !ELF
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FileHeader:
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Class: ELFCLASS64
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Data: ELFDATA2LSB
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Type: ET_DYN
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Machine: EM_X86_64
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Sections:
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- Name: .gnu.hash
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Type: SHT_GNU_HASH
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Flags: [ SHF_ALLOC ]
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Header:
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SymNdx: 0x1
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Shift2: 0x0
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BloomFilter: [ 0x0 ]
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HashBuckets: [ 0x0 ]
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HashValues: [ ]
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- Name: .dynamic
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Type: SHT_DYNAMIC
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Flags: [ SHF_ALLOC ]
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Link: 0
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Entries:
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- Tag: DT_GNU_HASH
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Value: 0x0
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- Tag: DT_NULL
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Value: 0x0
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DynamicSymbols: []
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ProgramHeaders:
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- Type: PT_LOAD
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Flags: [ PF_R, PF_X ]
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Sections:
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- Section: .gnu.hash
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- Section: .dynamic
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@ -2495,12 +2495,50 @@ template <typename ELFT> void ELFDumper<ELFT>::printGnuHashTable() {
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W.printNumber("First Hashed Symbol Index", GnuHashTable->symndx);
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W.printNumber("Num Mask Words", GnuHashTable->maskwords);
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W.printNumber("Shift Count", GnuHashTable->shift2);
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W.printHexList("Bloom Filter", GnuHashTable->filter());
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W.printList("Buckets", GnuHashTable->buckets());
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Elf_Sym_Range Syms = dynamic_symbols();
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unsigned NumSyms = std::distance(Syms.begin(), Syms.end());
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if (!NumSyms)
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reportError(createError("No dynamic symbol section"), ObjF->getFileName());
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ArrayRef<typename ELFT::Off> BloomFilter = GnuHashTable->filter();
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W.printHexList("Bloom Filter", BloomFilter);
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ArrayRef<Elf_Word> Buckets = GnuHashTable->buckets();
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W.printList("Buckets", Buckets);
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if (!DynSymRegion.Addr) {
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reportWarning(createError("unable to dump 'Values' for the SHT_GNU_HASH "
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"section: no dynamic symbol table found"),
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ObjF->getFileName());
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return;
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}
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size_t NumSyms = dynamic_symbols().size();
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if (!NumSyms) {
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reportWarning(createError("unable to dump 'Values' for the SHT_GNU_HASH "
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"section: the dynamic symbol table is empty"),
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ObjF->getFileName());
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return;
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}
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if (GnuHashTable->symndx >= NumSyms) {
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// A normal empty GNU hash table section produced by linker might have
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// symndx set to the number of dynamic symbols + 1 (for the zero symbol)
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// and have dummy null values in the Bloom filter and in the buckets
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// vector. It happens because the value of symndx is not important for
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// dynamic loaders when the GNU hash table is empty. They just skip the
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// whole object during symbol lookup. In such cases, the symndx value is
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// irrelevant and we should not report a warning.
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bool IsEmptyHashTable =
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llvm::all_of(Buckets, [](Elf_Word V) { return V == 0; });
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if (!IsEmptyHashTable) {
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reportWarning(
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createError("the first hashed symbol index (" +
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Twine(GnuHashTable->symndx) +
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") is larger than the number of dynamic symbols (" +
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Twine(NumSyms) + ")"),
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ObjF->getFileName());
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return;
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}
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}
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W.printHexList("Values", GnuHashTable->values(NumSyms));
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}
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