symtab: add support for CRC values from __kcrctab
Commit Message
From: Aleksei Vetrov <vvvvvv@google.com>
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>
---
src/abg-elf-helpers.cc | 47 ++++++++++++++++++++++++++++++++++++++++
src/abg-elf-helpers.h | 3 +++
src/abg-symtab-reader.cc | 5 ++++-
3 files changed, 54 insertions(+), 1 deletion(-)
Comments
Hello,
Giuliano Procida <gprocida@google.com> a écrit:
> From: Aleksei Vetrov <vvvvvv@google.com>
>
> 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>
Applied to master, thanks!
[...]
Cheers,
@@ -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.
@@ -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
//
@@ -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)