From 96fab38e02792a109c0d35ca2154e95a7b4c8fcb Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Mon, 8 Jun 2020 03:08:30 +0300 Subject: libcamera: ipa_module: Fix valgrind assertion failure MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit As the ELF parsing code uses non-const pointers to the ELF mapping, we have to map the module in private read-write mode. This causes issues with valgrind, due to the IPA manager mapping the module in shared read-only mode and valgrind having trouble loading debugging symbols later at dlopen time due to conflicting mappings. This is likely a bug in valgrind (reported as [1]), but we can easily work around it by using shared read-only mappings only. As such a mapping shouldn't be less efficient than private read-write mappings, switch the mapping type. This requires modifying the ELF parsing functions to operate on const memory, which is a good idea anyway as they're not supposed to modify the ELF file. [1] https://bugs.kde.org/show_bug.cgi?id=422601 Signed-off-by: Laurent Pinchart Reviewed-by: Niklas Söderlund Reviewed-by: Paul Elder --- src/libcamera/ipa_module.cpp | 42 +++++++++++++++++++++++------------------- 1 file changed, 23 insertions(+), 19 deletions(-) diff --git a/src/libcamera/ipa_module.cpp b/src/libcamera/ipa_module.cpp index 72e357ec..de512a7f 100644 --- a/src/libcamera/ipa_module.cpp +++ b/src/libcamera/ipa_module.cpp @@ -45,26 +45,27 @@ LOG_DEFINE_CATEGORY(IPAModule) namespace { template -typename std::remove_extent_t *elfPointer(Span elf, off_t offset, - size_t objSize) +typename std::remove_extent_t *elfPointer(Span elf, + off_t offset, size_t objSize) { size_t size = offset + objSize; if (size > elf.size() || size < objSize) return nullptr; return reinterpret_cast *> - (reinterpret_cast(elf.data()) + offset); + (reinterpret_cast(elf.data()) + offset); } template -typename std::remove_extent_t *elfPointer(Span elf, off_t offset) +typename std::remove_extent_t *elfPointer(Span elf, + off_t offset) { return elfPointer(elf, offset, sizeof(T)); } -int elfVerifyIdent(Span elf) +int elfVerifyIdent(Span elf) { - char *e_ident = elfPointer(elf, 0); + const char *e_ident = elfPointer(elf, 0); if (!e_ident) return -ENOEXEC; @@ -88,14 +89,15 @@ int elfVerifyIdent(Span elf) return 0; } -ElfW(Shdr) *elfSection(Span elf, ElfW(Ehdr) *eHdr, ElfW(Half) idx) +const ElfW(Shdr) *elfSection(Span elf, const ElfW(Ehdr) *eHdr, + ElfW(Half) idx) { if (idx >= eHdr->e_shnum) return nullptr; off_t offset = eHdr->e_shoff + idx * static_cast(eHdr->e_shentsize); - return elfPointer(elf, offset); + return elfPointer(elf, offset); } /** @@ -106,26 +108,26 @@ ElfW(Shdr) *elfSection(Span elf, ElfW(Ehdr) *eHdr, ElfW(Half) idx) * \return The memory region storing the symbol on success, or an empty span * otherwise */ -Span elfLoadSymbol(Span elf, const char *symbol) +Span elfLoadSymbol(Span elf, const char *symbol) { - ElfW(Ehdr) *eHdr = elfPointer(elf, 0); + const ElfW(Ehdr) *eHdr = elfPointer(elf, 0); if (!eHdr) return {}; - ElfW(Shdr) *sHdr = elfSection(elf, eHdr, eHdr->e_shstrndx); + const ElfW(Shdr) *sHdr = elfSection(elf, eHdr, eHdr->e_shstrndx); if (!sHdr) return {}; off_t shnameoff = sHdr->sh_offset; /* Locate .dynsym section header. */ - ElfW(Shdr) *dynsym = nullptr; + const ElfW(Shdr) *dynsym = nullptr; for (unsigned int i = 0; i < eHdr->e_shnum; i++) { sHdr = elfSection(elf, eHdr, i); if (!sHdr) return {}; off_t offset = shnameoff + sHdr->sh_name; - char *name = elfPointer(elf, offset); + const char *name = elfPointer(elf, offset); if (!name) return {}; @@ -146,16 +148,17 @@ Span elfLoadSymbol(Span elf, const char *symbol) off_t dynsym_nameoff = sHdr->sh_offset; /* Locate symbol in the .dynsym section. */ - ElfW(Sym) *targetSymbol = nullptr; + const ElfW(Sym) *targetSymbol = nullptr; unsigned int dynsym_num = dynsym->sh_size / dynsym->sh_entsize; for (unsigned int i = 0; i < dynsym_num; i++) { off_t offset = dynsym->sh_offset + dynsym->sh_entsize * i; - ElfW(Sym) *sym = elfPointer(elf, offset); + const ElfW(Sym) *sym = elfPointer(elf, offset); if (!sym) return {}; offset = dynsym_nameoff + sym->st_name; - char *name = elfPointer(elf, offset, strlen(symbol) + 1); + const char *name = elfPointer(elf, offset, + strlen(symbol) + 1); if (!name) return {}; @@ -176,7 +179,8 @@ Span elfLoadSymbol(Span elf, const char *symbol) if (!sHdr) return {}; off_t offset = sHdr->sh_offset + (targetSymbol->st_value - sHdr->sh_addr); - uint8_t *data = elfPointer(elf, offset, targetSymbol->st_size); + const uint8_t *data = elfPointer(elf, offset, + targetSymbol->st_size); if (!data) return {}; @@ -277,14 +281,14 @@ int IPAModule::loadIPAModuleInfo() return file.error(); } - Span data = file.map(0, -1, File::MapPrivate); + Span data = file.map(); int ret = elfVerifyIdent(data); if (ret) { LOG(IPAModule, Error) << "IPA module is not an ELF file"; return ret; } - Span info = elfLoadSymbol(data, "ipaModuleInfo"); + Span info = elfLoadSymbol(data, "ipaModuleInfo"); if (info.size() != sizeof(info_)) { LOG(IPAModule, Error) << "IPA module has no valid info"; return -EINVAL; -- cgit v1.2.1