561 Commits
Author SHA1 Message Date
Amit MachhiwalandMadhavan Srinivasan 6e65886fce selftests/powerpc: Suppress -Wmaybe-uninitialized with GCC 15
GCC 15 reports the below false positive '-Wmaybe-uninitialized' warning
in vphn_unpack_associativity() when building the powerpc selftests.

  # make -C tools/testing/selftests TARGETS="powerpc"
  [...]
    CC       test-vphn
  In file included from test-vphn.c:3:
  In function ‘vphn_unpack_associativity’,
      inlined from ‘test_one’ at test-vphn.c:371:2,
      inlined from ‘test_vphn’ at test-vphn.c:399:9:
  test-vphn.c:10:33: error: ‘be_packed’ may be used uninitialized [-Werror=maybe-uninitialized]
     10 | #define be16_to_cpup(x)         bswap_16(*x)
        |                                 ^~~~~~~~
  vphn.c:42:27: note: in expansion of macro ‘be16_to_cpup’
     42 |                 u16 new = be16_to_cpup(field++);
        |                           ^~~~~~~~~~~~
  In file included from test-vphn.c:19:
  vphn.c: In function ‘test_vphn’:
  vphn.c:27:16: note: ‘be_packed’ declared here
     27 |         __be64 be_packed[VPHN_REGISTER_COUNT];
        |                ^~~~~~~~~
  cc1: all warnings being treated as errors

When vphn_unpack_associativity() is called from hcall_vphn() in kernel
the error is not seen while building vphn.c during kernel compilation.
This is because the top level Makefile includes '-fno-strict-aliasing'
flag always.

The issue here is that GCC 15 emits '-Wmaybe-uninitialized' due to type
punning between __be64[] and __b16* when accessing the buffer via
be16_to_cpup(). The underlying object is fully initialized but GCC 15
fails to track the aliasing due to the strict aliasing violation here.
Please refer [1] and [2]. This results in a false positive warning which
is promoted to an error under '-Werror'. This problem is not seen when
the compilation is performed with GCC 13 and 14. An issue [1] has also
been created on GCC bugzilla.

The selftest compiles fine with '-fno-strict-aliasing'. Since this GCC
flag is used to compile vphn.c in kernel too, the same flag should be
used to build vphn tests when compiling vphn.c in the selftest as well.

Fix this by including '-fno-strict-aliasing' during vphn.c compilation
in the selftest. This keeps the build working while limiting the scope
of the suppression to building vphn tests.

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124427
[2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99768

Fixes: 58dae82843 ("selftests/powerpc: Add test for VPHN")
Reviewed-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Signed-off-by: Amit Machhiwal <amachhiw@linux.ibm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260313165426.43259-1-amachhiw@linux.ibm.com
2026-04-01 09:21:04 +05:30
Sayali PatilandMadhavan Srinivasan 146c9ab38b powerpc/selftests/copyloops: extend selftest to exercise __copy_tofrom_user_power7_vmx
The new PowerPC VMX fast path (__copy_tofrom_user_power7_vmx) is not
exercised by existing copyloops selftests. This patch updates
the selftest to exercise the VMX variant, ensuring the VMX copy path
is validated.

Changes include:
  - COPY_LOOP=test___copy_tofrom_user_power7_vmx with -D VMX_TEST is used
    in existing selftest build targets.
  - Inclusion of ../utils.c to provide get_auxv_entry() for hardware
    feature detection.
  - At runtime, the test skips execution if Altivec is not available.
  - Copy sizes above VMX_COPY_THRESHOLD are used to ensure the VMX
    path is taken.

This enables validation of the VMX fast path without affecting systems
that do not support Altivec.

Signed-off-by: Sayali Patil <sayalip@linux.ibm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260304122201.153049-2-sayalip@linux.ibm.com
2026-03-12 11:03:48 +05:30
Gopi Krishna MenonandMadhavan Srinivasan 42f53b3900 selftests/powerpc/pmu/: Add check_extended_reg_test to .gitignore
Add the check_extended_reg_test binary to .gitignore to avoid accidentally
staging the build artifact.

Signed-off-by: Gopi Krishna Menon <krishnagopi487@gmail.com>
Tested-by: Aditya Bodkhe <adityab1@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250922004439.2395-1-krishnagopi487@gmail.com
2025-12-22 17:55:07 +05:30
Thomas HuthandMadhavan Srinivasan 74db6cc331 powerpc: Replace __ASSEMBLY__ with __ASSEMBLER__ in non-uapi headers
While the GCC and Clang compilers already define __ASSEMBLER__
automatically when compiling assembler code, __ASSEMBLY__ is a
macro that only gets defined by the Makefiles in the kernel.
This is bad since macros starting with two underscores are names
that are reserved by the C language. It can also be very confusing
for the developers when switching between userspace and kernelspace
coding, or when dealing with uapi headers that rather should use
__ASSEMBLER__  instead. So let's standardize now on the __ASSEMBLER__
macro that is provided by the compilers.

This is almost a completely mechanical patch (done with a simple
"sed -i" statement), apart from tweaking two comments manually in
arch/powerpc/include/asm/bug.h and arch/powerpc/include/asm/kasan.h
(which did not have proper underscores at the end) and fixing a
checkpatch error about spaces in arch/powerpc/include/asm/spu_csa.h.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250801082007.32904-3-thuth@redhat.com
2025-09-01 13:23:29 +05:30
Linus Torvalds 7b667acd69 Merge tag 'powerpc-6.15-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Madhavan Srinivasan:

 - Remove support for IBM Cell Blades

 - SMP support for microwatt platform

 - Support for inline static calls on PPC32

 - Enable pmu selftests for power11 platform

 - Enable hardware trace macro (HTM) hcall support

 - Support for limited address mode capability

 - Changes to RMA size from 512 MB to 768 MB to handle fadump

 - Misc fixes and cleanups

Thanks to Abhishek Dubey, Amit Machhiwal, Andreas Schwab, Arnd Bergmann,
Athira Rajeev, Avnish Chouhan, Christophe Leroy, Disha Goel, Donet Tom,
Gaurav Batra, Gautam Menghani, Hari Bathini, Kajol Jain, Kees Cook,
Mahesh Salgaonkar, Michael Ellerman, Paul Mackerras, Ritesh Harjani
(IBM), Sathvika Vasireddy, Segher Boessenkool, Sourabh Jain, Vaibhav
Jain, and Venkat Rao Bagalkote.

* tag 'powerpc-6.15-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (61 commits)
  powerpc/kexec: fix physical address calculation in clear_utlb_entry()
  crypto: powerpc: Mark ghashp8-ppc.o as an OBJECT_FILES_NON_STANDARD
  powerpc: Fix 'intra_function_call not a direct call' warning
  powerpc/perf: Fix ref-counting on the PMU 'vpa_pmu'
  KVM: PPC: Enable CAP_SPAPR_TCE_VFIO on pSeries KVM guests
  powerpc/prom_init: Fixup missing #size-cells on PowerBook6,7
  powerpc/microwatt: Add SMP support
  powerpc: Define config option for processors with broadcast TLBIE
  powerpc/microwatt: Define an idle power-save function
  powerpc/microwatt: Device-tree updates
  powerpc/microwatt: Select COMMON_CLK in order to get the clock framework
  net: toshiba: Remove reference to PPC_IBM_CELL_BLADE
  net: spider_net: Remove powerpc Cell driver
  cpufreq: ppc_cbe: Remove powerpc Cell driver
  genirq: Remove IRQ_EDGE_EOI_HANDLER
  docs: Remove reference to removed CBE_CPUFREQ_SPU_GOVERNOR
  powerpc: Remove UDBG_RTAS_CONSOLE
  powerpc/io: Use standard barrier macros in io.c
  powerpc/io: Rename _insw_ns() etc.
  powerpc/io: Use generic raw accessors
  ...
2025-03-27 19:39:08 -07:00
Madhavan SrinivasanandCatalin Marinas 73276cee1a selftest/powerpc/mm/pkey: fix build-break introduced by commit 00894c3fc9
Build break was reported in the powerpc mailing list for next-20250218 with below errors

make[1]: Nothing to be done for 'all'.
BUILD_TARGET=/root/venkat/linux-next/tools/testing/selftests/powerpc/mm; mkdir -p $BUILD_TARGET; make OUTPUT=$BUILD_TARGET -k -C mm all
  CC       pkey_exec_prot
In file included from pkey_exec_prot.c:18:
/root/venkat/linux-next/tools/testing/selftests/powerpc/include/pkeys.h: In function ‘pkeys_unsupported’:
/root/venkat/linux-next/tools/testing/selftests/powerpc/include/pkeys.h:96:34: error: ‘PKEY_UNRESTRICTED’ undeclared (first use in this function)
   96 |         pkey = sys_pkey_alloc(0, PKEY_UNRESTRICTED);
      |                                  ^~~~~~~~~~~~~~~~~

https://lore.kernel.org/all/20250113170619.484698-2-yury.khrustalev@arm.com/ patchset
has been queued to arm64/for-next/pkey_unrestricted which is causing a build break
in the selftest/powerpc builds.

Commit 6d61527d93 ("mm/pkey: Add PKEY_UNRESTRICTED macro") added a macro
PKEY_UNRESTRICTED to handle implicit literal value of 0x0 (which is "unrestricted").
Add the same to selftest/powerpc/pkeys.h to fix the reported build break.

Fixes: 00894c3fc9 ("selftests/powerpc: Use PKEY_UNRESTRICTED macro")
Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Closes: https://lore.kernel.org/lkml/3267ea6e-5a1a-4752-96ef-8351c912d386@linux.ibm.com/T/
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://lore.kernel.org/r/20250311084129.39308-1-maddy@linux.ibm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2025-03-11 15:16:10 +00:00
Yury KhrustalevandCatalin Marinas 00894c3fc9 selftests/powerpc: Use PKEY_UNRESTRICTED macro
Replace literal 0 with macro PKEY_UNRESTRICTED where pkey_*() functions
are used in mm selftests for memory protection keys for ppc target.

Signed-off-by: Yury Khrustalev <yury.khrustalev@arm.com>
Suggested-by: Kevin Brodsky <kevin.brodsky@arm.com>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Link: https://lore.kernel.org/r/20250113170619.484698-4-yury.khrustalev@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2025-02-17 18:16:36 +00:00
Athira RajeevandMadhavan Srinivasan c96b1402cc selftests/powerpc/pmu: Update comment with details to understand auxv_generic_compat_pmu() utility function
auxv_generic_compat_pmu() utility function is to detect whether the
system is having generic compat PMU. The check is based on base platform
value from /proc/self/auxv. Update the comment with details on how auxv
is used to detect the platform.

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250113075858.45137-5-atrajeev@linux.vnet.ibm.com
2025-02-11 11:33:52 +05:30
Kajol JainandMadhavan Srinivasan 9785def259 selftests/powerpc/pmu: Add interface test for extended reg support
The testcase uses check_extended_regs_support and
perf_get_platform_reg_mask function to check if the
platform has extended reg support. This will help to
check if sampling pmu selftest is enabled or not for
a given platform.

Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250113075858.45137-4-atrajeev@linux.vnet.ibm.com
2025-02-11 11:33:51 +05:30
Athira RajeevandMadhavan Srinivasan 43751c3ce2 tools/testing/selftests/powerpc/pmu: Update comment description to mention ISA v3.1 for power10 and above
Updated the comments in the pmu selftests to include
power11/ISA v3.1 where ever required.

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250113075858.45137-3-atrajeev@linux.vnet.ibm.com
2025-02-11 11:33:51 +05:30
Athira RajeevandMadhavan Srinivasan 520ee327c5 tools/testing/selftests/powerpc: Add check for power11 pvr for pmu selfests
Some of the tests depends on pvr value to choose
the event. Example:
- event_alternatives_tests_p10: alternative event depends
  on registered PMU driver which is based on pvr
- generic_events_valid_test varies based on platform
- bhrb_filter_map_test: again its dependent on pmu to
  decide which bhrb filter to use
- reserved_bits_mmcra_sample_elig_mode: randome sampling
  mode reserved bits is also varies based on platform

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Tested-by: Disha Goel <disgoel@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250113075858.45137-2-atrajeev@linux.vnet.ibm.com
2025-02-11 11:33:51 +05:30
Athira RajeevandMadhavan Srinivasan fd4d2f3251 tools/testing/selftests/powerpc: Enable pmu selftests for power11
Add check for power11 pvr in the selftest utility
functions. Selftests uses pvr value to check for platform
support inorder to run the tests. pvr is also used to
send the extended mask value to capture sampling registers.

Update some of the utility functions to use hwcap2 inorder
to return platform specific bits from sampling registers.

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250113075858.45137-1-atrajeev@linux.vnet.ibm.com
2025-02-11 11:33:51 +05:30
Michael EllermanandMadhavan Srinivasan 2bf66e66d2 selftests/powerpc: Fix argument order to timer_sub()
Commit c814bf9589 ("powerpc/selftests: Use timersub() for
gettimeofday()"), got the order of arguments to timersub() wrong,
leading to a negative time delta being reported, eg:

  test: gettimeofday
  tags: git_version:v6.12-rc5-409-gdddf291c3030
  time = -3.297781
  success: gettimeofday

The correct order is minuend, subtrahend, which in this case is end,
start. Which gives:

  test: gettimeofday
  tags: git_version:v6.12-rc5-409-gdddf291c3030-dirty
  time = 3.300650
  success: gettimeofday

Fixes: c814bf9589 ("powerpc/selftests: Use timersub() for gettimeofday()")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20241218114347.428108-1-mpe@ellerman.id.au
2025-01-11 10:39:45 +05:30
Madhavan Srinivasan 65f5038352 selftest/powerpc/ptrace: Cleanup duplicate macro definitions
Both core-pkey.c and ptrace-pkey.c tests have
similar macro definitions, move them to "pkeys.h"
and remove the macro definitions from the C file.

Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20241216160257.87252-3-maddy@linux.ibm.com
2024-12-18 13:40:12 +05:30
Madhavan Srinivasan b0e1b95b15 selftest/powerpc/ptrace/ptrace-pkey: Remove duplicate macros
./powerpc/ptrace/Makefile includes flags.mk.
In flags.mk, -I$(selfdir)/powerpc/include is
always included as part of CFLAGS. So it will
pick up the "pkeys.h" defined in powerpc/include.

ptrace-pkey.c test has macros defined which
are part of "pkeys.h" header file. Remove those
duplicates and include "pkeys.h"

Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20241216160257.87252-2-maddy@linux.ibm.com
2024-12-18 13:40:12 +05:30
Madhavan Srinivasan 026ac4dda8 selftest/powerpc/ptrace/core-pkey: Remove duplicate macros
./powerpc/ptrace/Makefile includes flags.mk. In flags.mk,
-I$(selfdir)/powerpc/include is always included as part of
CFLAGS. So it will pick up the "pkeys.h" defined in
powerpc/include.

core-pkey.c test has couple of macros defined which
are part of "pkeys.h" header file. Remove those
duplicates and include "pkeys.h"

Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20241216160257.87252-1-maddy@linux.ibm.com
2024-12-18 13:40:12 +05:30
Zhu JunandMadhavan Srinivasan 3a7a53c8d4 selftests/powerpc: Fix typo in test-vphn.c
The word 'accross' is wrong, so fix it.

Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20241204080149.11759-1-zhujun2@cmss.chinamobile.com
2024-12-10 08:34:51 +05:30
zhang jiaoandMichael Ellerman 7ca93aa920 selftests/powerpc: Remove the path after initialization.
If there were no anamolies noted, then we can simply remove the log file
and return, but only after the path variable has been initialized.

Signed-off-by: zhang jiao <zhangjiao2@cmss.chinamobile.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/20240930012757.2395-1-zhangjiao2@cmss.chinamobile.com
2024-11-14 22:41:00 +11:00
Michael Ellerman a8a54a65ca selftests/powerpc: Detect taint change in mitigation patching test
Currently the mitigation patching test errors out if the kernel is
tainted prior to the test running.

That causes the test to fail unnecessarily if some other test has caused
the kernel to be tainted, or if a proprietary or force module is loaded
for example.

Instead just warn if the kernel is tainted to begin with, and only
report a change in the taint state as an error in the test.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/20241106130453.1741013-5-mpe@ellerman.id.au
2024-11-07 22:36:31 +11:00
Michael Ellerman c6a75555b4 selftests/powerpc: Return errors from all tests
Fix some tests which weren't returning an error code from main.

Although these tests only ever return success, they can still fail if
they time out and the harness kills them. If that happens they still
return success to the shell, which is incorrect and confuses the higher
level error reporting.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/20241106130453.1741013-4-mpe@ellerman.id.au
2024-11-07 22:36:31 +11:00
Michael Ellerman d5f578f90a selftests/powerpc: Fix 32-bit BE build errors on Ubuntu 24.04
Starting with Ubuntu 24.04, building the selftests with the big endian
compiler (which defaults to 32-bit) fails with errors:

  stack_expansion_ldst.c:178:37: error: format '%lx' expects argument
  of type 'long unsigned int', but argument 2 has type 'rlim_t' {aka 'long long unsigned int'}
  subpage_prot.c:214:38: error: format '%lx' expects argument of type
  'long unsigned int', but argument 3 has type 'off_t' {aka 'long long int'}

Prior to 24.04 rlim_t was long unsigned int, and off_t was long int.

Cast to unsigned long long and long long before passing to printf to
avoid the errors.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/20241106130453.1741013-3-mpe@ellerman.id.au
2024-11-07 22:36:30 +11:00
Michael Ellerman 5543d59595 selftests/powerpc: Give all tests 2 minutes timeout
Each of the powerpc selftests runs with a timeout of 2 minutes by
default (see tools/testing/selftests/powerpc/harness.c).

But when tests are run with run_kselftest.sh it uses a timeout of 45
seconds, meaning some tests run OK standalone but fail when run with the
test runner.

So tell run_kselftest.sh to give each test 130 seconds, that should
allow the tests to complete, or be killed by the powerpc test harness
after 2 minutes. If for some reason the harness fails, or for the few
tests that don't use the harness, the 130 second timeout should catch
them if they get stuck.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/20241106130453.1741013-2-mpe@ellerman.id.au
2024-11-07 22:36:30 +11:00
Michael Ellerman 3b9bde403a selftests/powerpc: Lower run time of count_stcx_fail test
The count_stcx_fail test runs for close to or just over 2 minutes, which
means it sometimes times out.

That's overkill for a test that just demonstrates some PMU counters
are working. Drop the 64 billion instruction case, to lower the runtime
to ~30s.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/20241106130453.1741013-1-mpe@ellerman.id.au
2024-11-07 22:36:30 +11:00
Madhavan SrinivasanandMichael Ellerman 8c9c01ce69 selftests/powerpc: Allow building without static libc
Currently exec-target.c is linked statically with libc, which on Fedora
at least requires installing an additional package (glibc-static).

If that package is not installed the build fails with:

    CC       exec_target
  /usr/bin/ld: cannot find -lc: No such file or directory
  collect2: error: ld returned 1 exit status

All exec_target.c does is call sys_exit, which can be done easily enough
using inline assembly, and removes the requirement for a static libc to
be installed.

Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240812094152.418586-1-maddy@linux.ibm.com
2024-09-09 16:35:04 +10:00
Michael Ellerman 8b7f59de92 selftests/powerpc: Fix build with USERCFLAGS set
Currently building the powerpc selftests with USERCFLAGS set to anything
causes the build to break:

  $ make -C tools/testing/selftests/powerpc V=1 USERCFLAGS=-Wno-error
  ...
  gcc -Wno-error    cache_shape.c ...
  cache_shape.c:18:10: fatal error: utils.h: No such file or directory
     18 | #include "utils.h"
        |          ^~~~~~~~~
  compilation terminated.

This happens because the USERCFLAGS are added to CFLAGS in lib.mk, which
causes the check of CFLAGS in powerpc/flags.mk to skip setting CFLAGS at
all, resulting in none of the usual CFLAGS being passed. That can
be seen in the output above, the only flag passed to the compiler is
-Wno-error.

Fix it by dropping the conditional setting of CFLAGS in flags.mk.
Instead always set CFLAGS, but also append USERCFLAGS if they are set.

Note that appending to CFLAGS (with +=) wouldn't work, because flags.mk
is included by multiple Makefiles (to support partial builds), causing
CFLAGS to be appended to multiple times. Additionally that would place
the USERCFLAGS prior to the standard CFLAGS, meaning the USERCFLAGS
couldn't override the standard flags. Being able to override the
standard flags is desirable, for example for adding -Wno-error.

With the fix in place, the CFLAGS are set correctly, including the
USERCFLAGS:

  $ make -C tools/testing/selftests/powerpc V=1 USERCFLAGS=-Wno-error
  ...
  gcc -std=gnu99 -O2 -Wall -Werror -DGIT_VERSION='"v6.10-rc2-7-gdea17e7e56c3"'
  -I/home/michael/linux/tools/testing/selftests/powerpc/include -Wno-error
  cache_shape.c ...

Fixes: 5553a79387 ("selftests/powerpc: Add flags.mk to support pmu buildable")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240706120833.909853-1-mpe@ellerman.id.au
2024-07-06 22:10:14 +10:00