| Message ID | 20240614233105.265009-1-jhubbard@nvidia.com |
|---|---|
| Headers | show |
| Series | selftests/vDSO: fix clang build errors, and Makefile cleanup | expand |
On 6/14/24 4:31 PM, John Hubbard wrote: > Hi, > > Jason A. Donenfeld, I've added you because I ended up looking through > your latest "implement getrandom() in vDSO" series [1], which also > touches this Makefile, so just a heads up about upcoming (minor) merge > conflicts. Belatedly adding Carlos Llamas and Thomas Gleixner to Cc. > > Changes since v2: > > 1. Added two patches, both of which apply solely to the Makefile. > These provide a smaller, cleaner, and more accurate Makefile. > > 2. Added Reviewed-by and Tested-by tags for the original patch, which > fixes all of the clang errors and warnings for this selftest. > > 3. Removed an obsolete blurb from the commit description of the original > patch, now that Valentin Obst LLVM build fix has been merged. > > > [1] https://lore.kernel.org/20240614190646.2081057-1-Jason@zx2c4.com > > > John Hubbard (3): > selftests/vDSO: fix clang build errors and warnings > selftests/mm: remove partially duplicated "all:" target in Makefile > selftests/vDSO: remove duplicate compiler invocations from Makefile > > tools/testing/selftests/vDSO/Makefile | 29 ++++++++----------- > tools/testing/selftests/vDSO/parse_vdso.c | 16 ++++++---- > .../selftests/vDSO/vdso_standalone_test_x86.c | 18 ++++++++++-- > 3 files changed, 39 insertions(+), 24 deletions(-) > > > base-commit: 2ccbdf43d5e758f8493a95252073cf9078a5fea5 thanks,
Also Cc'ing Thomas Gleixner on this one, sorry for the omission. On 6/14/24 4:31 PM, John Hubbard wrote: > When building with clang, via: > > make LLVM=1 -C tools/testing/selftests > > ...there are several warnings, and an error. This fixes all of those and > allows these tests to run and pass. > > 1. Fix linker error (undefined reference to memcpy) by providing a local > version of memcpy. > > 2. clang complains about using this form: > > if (g = h & 0xf0000000) > > ...so factor out the assignment into a separate step. > > 3. The code is passing a signed const char* to elf_hash(), which expects > a const unsigned char *. There are several callers, so fix this at > the source by allowing the function to accept a signed argument, and > then converting to unsigned operations, once inside the function. > > 4. clang doesn't have __attribute__((externally_visible)) and generates > a warning to that effect. Fortunately, gcc 12 and gcc 13 do not seem > to require that attribute in order to build, run and pass tests here, > so remove it. > > Reviewed-by: Carlos Llamas <cmllamas@google.com> > Reviewed-by: Edward Liaw <edliaw@google.com> > Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com> > Tested-by: Muhammad Usama Anjum <usama.anjum@collabora.com> > Signed-off-by: John Hubbard <jhubbard@nvidia.com> > --- > tools/testing/selftests/vDSO/parse_vdso.c | 16 +++++++++++----- > .../selftests/vDSO/vdso_standalone_test_x86.c | 18 ++++++++++++++++-- > 2 files changed, 27 insertions(+), 7 deletions(-) > > diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c > index 413f75620a35..4ae417372e9e 100644 > --- a/tools/testing/selftests/vDSO/parse_vdso.c > +++ b/tools/testing/selftests/vDSO/parse_vdso.c > @@ -55,14 +55,20 @@ static struct vdso_info > ELF(Verdef) *verdef; > } vdso_info; > > -/* Straight from the ELF specification. */ > -static unsigned long elf_hash(const unsigned char *name) > +/* > + * Straight from the ELF specification...and then tweaked slightly, in order to > + * avoid a few clang warnings. > + */ > +static unsigned long elf_hash(const char *name) > { > unsigned long h = 0, g; > - while (*name) > + const unsigned char *uch_name = (const unsigned char *)name; > + > + while (*uch_name) > { > - h = (h << 4) + *name++; > - if (g = h & 0xf0000000) > + h = (h << 4) + *uch_name++; > + g = h & 0xf0000000; > + if (g) > h ^= g >> 24; > h &= ~g; > } > diff --git a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c > index 8a44ff973ee1..27f6fdf11969 100644 > --- a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c > +++ b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c > @@ -18,7 +18,7 @@ > > #include "parse_vdso.h" > > -/* We need a libc functions... */ > +/* We need some libc functions... */ > int strcmp(const char *a, const char *b) > { > /* This implementation is buggy: it never returns -1. */ > @@ -34,6 +34,20 @@ int strcmp(const char *a, const char *b) > return 0; > } > > +/* > + * The clang build needs this, although gcc does not. > + * Stolen from lib/string.c. > + */ > +void *memcpy(void *dest, const void *src, size_t count) > +{ > + char *tmp = dest; > + const char *s = src; > + > + while (count--) > + *tmp++ = *s++; > + return dest; > +} > + > /* ...and two syscalls. This is x86-specific. */ > static inline long x86_syscall3(long nr, long a0, long a1, long a2) > { > @@ -70,7 +84,7 @@ void to_base10(char *lastdig, time_t n) > } > } > > -__attribute__((externally_visible)) void c_main(void **stack) > +void c_main(void **stack) > { > /* Parse the stack */ > long argc = (long)*stack; thanks,
On 6/14/24 4:34 PM, John Hubbard wrote: > On 6/14/24 4:31 PM, John Hubbard wrote: >> Hi, >> >> Jason A. Donenfeld, I've added you because I ended up looking through >> your latest "implement getrandom() in vDSO" series [1], which also >> touches this Makefile, so just a heads up about upcoming (minor) merge >> conflicts. > > Belatedly adding Carlos Llamas and Thomas Gleixner to Cc. Hi Shuah, Andy, Thomas, Patches 2 and 3 fix up the Makefile, and I'm particularly eager to get those merged into 6.10, because the existing Makefile is leading people astray. See the thread in [2] for an example of that. As a result, Jason Donenfeld is now waiting for this, for his "implement getrandom() in vDSO" series. The Makefile is more of a kselftest infrastructure thing in a way, so maybe Shuah can pull this in? I'm casting about for ways to move forward. [2] https://lore.kernel.org/13483c92-cac5-4a3a-891f-22eb006c533b@nvidia.com thanks,