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symtab: add support for CRC values from __kcrctab

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New kernels changed the format of storing CRC values from absolute
symbol value to the address in __kcrctab or __kcrctab_gpl section.
This change adds support for CRC values described in this format.

	* src/abg-elf-helpers.h (get_crc_for_symbol): Defined new
	helper function to extract CRC from ELF symbol.
	* src/abg-elf-helpers.cc (get_crc_for_symbol): Implemented this
	function with support of old and new CRC values format.
	* src/abg-symtab-reader.cc (symtab::load_): Used the new
	function when building CRC values map.

Change-Id: I7de5c737d5caaef0c5b7b2ea0d448368889a16be
Signed-off-by: Aleksei Vetrov <vvvvvv@google.com>
Signed-off-by: Dodji Seketeli <dodji@redhat.com>
This commit is contained in:
Aleksei Vetrov 2022-11-18 09:09:07 +00:00 committed by Dodji Seketeli
parent 102758ad9a
commit c6ac7db457
3 changed files with 54 additions and 1 deletions
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47
src/abg-elf-helpers.cc
View File

@ -905,6 +905,53 @@ get_version_for_symbol(Elf* elf_handle,
return false;
}
/// Return the CRC from the "__crc_" symbol.
///
/// @param elf_handle the elf handle to use.
///
/// @param crc_symbol symbol containing CRC value.
///
/// @param crc_value the CRC found for @p crc_symbol.
///
/// @return true iff a CRC was found for given @p crc_symbol.
bool
get_crc_for_symbol(Elf* elf_handle, GElf_Sym* crc_symbol, uint32_t& crc_value)
{
size_t crc_section_index = crc_symbol->st_shndx;
uint64_t crc_symbol_value = crc_symbol->st_value;
if (crc_section_index == SHN_ABS)
{
crc_value = crc_symbol_value;
return true;
}
Elf_Scn* kcrctab_section = elf_getscn(elf_handle, crc_section_index);
if (kcrctab_section == NULL)
return false;
GElf_Shdr sheader_mem;
GElf_Shdr* sheader = gelf_getshdr(kcrctab_section, &sheader_mem);
if (sheader == NULL)
return false;
Elf_Data* kcrctab_data = elf_rawdata(kcrctab_section, NULL);
if (kcrctab_data == NULL)
return false;
if (crc_symbol_value < sheader->sh_addr)
return false;
size_t offset = crc_symbol_value - sheader->sh_addr;
if (offset + sizeof(uint32_t) > kcrctab_data->d_size
|| offset + sizeof(uint32_t) > sheader->sh_size)
return false;
crc_value = *reinterpret_cast<uint32_t*>(
reinterpret_cast<char*>(kcrctab_data->d_buf) + offset);
return true;
}
/// Test if the architecture of the current binary is ppc64.
///
/// @param elf_handle the ELF handle to consider.

3
src/abg-elf-helpers.h
View File

@ -141,6 +141,9 @@ get_version_for_symbol(Elf* elf_handle,
bool get_def_version,
elf_symbol::version& version);
bool
get_crc_for_symbol(Elf* elf_handle, GElf_Sym* crc_symbol, uint32_t& crc_value);
//
// Architecture specific helpers
//

5
src/abg-symtab-reader.cc
View File

@ -314,7 +314,10 @@ symtab::load_(Elf* elf_handle,
}
if (is_kernel && name.rfind("__crc_", 0) == 0)
{
ABG_ASSERT(crc_values.emplace(name.substr(6), sym->st_value).second);
uint32_t crc_value;
ABG_ASSERT(elf_helpers::get_crc_for_symbol(elf_handle,
sym, crc_value));
ABG_ASSERT(crc_values.emplace(name.substr(6), crc_value).second);
continue;
}
if (strings_section && is_kernel && name.rfind("__kstrtabns_", 0) == 0)