| Message ID | 20230623140825.ehqk5ndl7uftstwy@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | scripts/mksysmap: Ignore prefixed KCFI symbols | expand |
Hi Pierre-Clément, On Fri, Jun 23, 2023 at 7:08 AM Pierre-Clément Tosi <ptosi@google.com> wrote: > > The (relatively) new KCFI feature in LLVM/Clang encodes type information > for C functions by generating symbols named __kcfi_typeid_<fname>, which > can then be referenced from assembly. However, some custom build rules > (e.g. EFI, nVHE, or early PIE on arm64) use objcopy to add a prefix to > all the symbols in their object files, making mksysmap's ignore filter > miss those KCFI symbols. > > Therefore, explicitly list those twice-prefixed KCFI symbols as ignored. > > Alternatively, this could also be achieved in a less verbose way by > ignoring any symbol containing the string "__kcfi_typeid_". However, > listing the combined prefixes explicitly saves us from running the small > risk of ignoring symbols that should be kept. > > Signed-off-by: Pierre-Clément Tosi <ptosi@google.com> > --- > scripts/mksysmap | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/scripts/mksysmap b/scripts/mksysmap > index 26f39772f7a5..17cf4292e26b 100755 > --- a/scripts/mksysmap > +++ b/scripts/mksysmap > @@ -61,7 +61,10 @@ ${NM} -n ${1} | sed >${2} -e " > / __microLA25Thunk_/d > > # CFI type identifiers > +/ __efistub___kcfi_typeid_/d Does the existing __efistub_/d rule not catch this? > / __kcfi_typeid_/d > +/ __kvm_nvhe___kcfi_typeid_/d > +/ __pi___kcfi_typeid_/d Either way, otherwise this looks reasonable to me. Thanks for the patch! Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Sami
On Sat, Jun 24, 2023 at 5:45 AM Sami Tolvanen <samitolvanen@google.com> wrote: > > Hi Pierre-Clément, > > On Fri, Jun 23, 2023 at 7:08 AM Pierre-Clément Tosi <ptosi@google.com> wrote: > > > > The (relatively) new KCFI feature in LLVM/Clang encodes type information > > for C functions by generating symbols named __kcfi_typeid_<fname>, which > > can then be referenced from assembly. However, some custom build rules > > (e.g. EFI, nVHE, or early PIE on arm64) use objcopy to add a prefix to > > all the symbols in their object files, making mksysmap's ignore filter > > miss those KCFI symbols. > > > > Therefore, explicitly list those twice-prefixed KCFI symbols as ignored. > > > > Alternatively, this could also be achieved in a less verbose way by > > ignoring any symbol containing the string "__kcfi_typeid_". However, > > listing the combined prefixes explicitly saves us from running the small > > risk of ignoring symbols that should be kept. > > > > Signed-off-by: Pierre-Clément Tosi <ptosi@google.com> > > --- > > scripts/mksysmap | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/scripts/mksysmap b/scripts/mksysmap > > index 26f39772f7a5..17cf4292e26b 100755 > > --- a/scripts/mksysmap > > +++ b/scripts/mksysmap > > @@ -61,7 +61,10 @@ ${NM} -n ${1} | sed >${2} -e " > > / __microLA25Thunk_/d > > > > # CFI type identifiers > > +/ __efistub___kcfi_typeid_/d > > Does the existing __efistub_/d rule not catch this? Agree with Sami. This line looks redundant to me. > > > / __kcfi_typeid_/d > > +/ __kvm_nvhe___kcfi_typeid_/d > > +/ __pi___kcfi_typeid_/d > > Either way, otherwise this looks reasonable to me. Thanks for the patch! > > Reviewed-by: Sami Tolvanen <samitolvanen@google.com> > > Sami
diff --git a/scripts/mksysmap b/scripts/mksysmap index 26f39772f7a5..17cf4292e26b 100755 --- a/scripts/mksysmap +++ b/scripts/mksysmap @@ -61,7 +61,10 @@ ${NM} -n ${1} | sed >${2} -e " / __microLA25Thunk_/d # CFI type identifiers +/ __efistub___kcfi_typeid_/d / __kcfi_typeid_/d +/ __kvm_nvhe___kcfi_typeid_/d +/ __pi___kcfi_typeid_/d # CRC from modversions / __crc_/d
The (relatively) new KCFI feature in LLVM/Clang encodes type information for C functions by generating symbols named __kcfi_typeid_<fname>, which can then be referenced from assembly. However, some custom build rules (e.g. EFI, nVHE, or early PIE on arm64) use objcopy to add a prefix to all the symbols in their object files, making mksysmap's ignore filter miss those KCFI symbols. Therefore, explicitly list those twice-prefixed KCFI symbols as ignored. Alternatively, this could also be achieved in a less verbose way by ignoring any symbol containing the string "__kcfi_typeid_". However, listing the combined prefixes explicitly saves us from running the small risk of ignoring symbols that should be kept. Signed-off-by: Pierre-Clément Tosi <ptosi@google.com> --- scripts/mksysmap | 3 +++ 1 file changed, 3 insertions(+)