On Wed, Aug 06, 2025 at 08:59:59AM +0200, Christophe Leroy wrote:

Le 05/08/2025 à 13:59, Venkat Rao Bagalkote a écrit :

quoted

On 05/08/25 1:04 pm, Christophe Leroy wrote:

quoted

Le 05/08/2025 à 08:27, Saket Kumar Bhaskar a écrit :

quoted

bpf_jit_emit_probe_mem_store() is introduced to emit instructions for
storing memory values depending on the size (byte, halfword,
word, doubleword).

Build break with this patch

  CC      arch/powerpc/net/bpf_jit_comp64.o
arch/powerpc/net/bpf_jit_comp64.c:395:12: error:
'bpf_jit_emit_probe_mem_store' defined but not used [-Werror=unused-
function]
 static int bpf_jit_emit_probe_mem_store(struct codegen_context
*ctx, u32 src_reg, s16 off,
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[4]: *** [scripts/Makefile.build:287: arch/powerpc/net/
bpf_jit_comp64.o] Error 1

I tried this on top of bpf-next, and for me build passed.

Build of _this_ patch (alone) passed ?

This patch defines a static function but doesn't use it, so the build must
breaks because of that, unless you have set CONFIG_PPC_DISABLE_WERROR.

Following patch starts using this function so then the build doesn't break
anymore. But until next patch is applied the build doesn't work. Both
patches have to be squashed together in order to not break bisectability of
the kernel.

Christophe

Got it Chris, will squash both the patches together in v2.

quoted

Note: I applied https://eur01.safelinks.protection.outlook.com/?
url=https%3A%2F%2Flore.kernel.org%2Fbpf%2F20250717202935.29018-2- puranjay%40kernel.org%2F&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C0468473019834e07ef2b08ddd4179b9c%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638899920058624267%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=iZLg9NUWxtH3vO1STI8wRYLzwvhohd2KKTAGYDe3WnM%3D&reserved=0
before applying current patch.

gcc version 14.2.1 20250110

uname -r: 6.16.0-gf2844c7fdb07

bpf-next repo: https://eur01.safelinks.protection.outlook.com/? url=https%3A%2F%2Fkernel.googlesource.com%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Fbpf%2Fbpf-next&data=05%7C02%7Cchristophe.leroy%40csgroup.eu%7C0468473019834e07ef2b08ddd4179b9c%7C8b87af7d86474dc78df45f69a2011bb5%7C0%7C0%7C638899920058644309%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=OrMauttrzPbaFYhzKdkH5l%2FltISc95MwitnUC7YLhJQ%3D&reserved=0

HEAD:

commit f3af62b6cee8af9f07012051874af2d2a451f0e5 (origin/master, origin/
HEAD)
Author: Tao Chen [off-list ref]
Date:   Wed Jul 23 22:44:42 2025 +0800

     bpftool: Add bash completion for token argument


Build Success logs:

   TEST-OBJ [test_progs-cpuv4] xdp_vlan.test.o
   TEST-OBJ [test_progs-cpuv4] xdpwall.test.o
   TEST-OBJ [test_progs-cpuv4] xfrm_info.test.o
   BINARY   bench
   BINARY   test_maps
   BINARY   test_progs
   BINARY   test_progs-no_alu32
   BINARY   test_progs-cpuv4


Regards,

Venkat.

quoted

quoted

Signed-off-by: Saket Kumar Bhaskar <redacted>
---
  arch/powerpc/net/bpf_jit_comp64.c | 30 ++++++++++++++++++++++++++++++
  1 file changed, 30 insertions(+)

diff --git a/arch/powerpc/net/bpf_jit_comp64.c

b/arch/powerpc/net/ bpf_jit_comp64.c
index 025524378443..489de21fe3d6 100644

--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c

@@ -409,6 +409,36 @@ asm (

  "        blr                ;"
  );
  +static int bpf_jit_emit_probe_mem_store(struct
codegen_context *ctx, u32 src_reg, s16 off,
+                    u32 code, u32 *image)
+{
+    u32 tmp1_reg = bpf_to_ppc(TMP_REG_1);
+    u32 tmp2_reg = bpf_to_ppc(TMP_REG_2);
+
+    switch (BPF_SIZE(code)) {
+    case BPF_B:
+        EMIT(PPC_RAW_STB(src_reg, tmp1_reg, off));
+        break;
+    case BPF_H:
+        EMIT(PPC_RAW_STH(src_reg, tmp1_reg, off));
+        break;
+    case BPF_W:
+        EMIT(PPC_RAW_STW(src_reg, tmp1_reg, off));
+        break;
+    case BPF_DW:
+        if (off % 4) {
+            EMIT(PPC_RAW_LI(tmp2_reg, off));
+            EMIT(PPC_RAW_STDX(src_reg, tmp1_reg, tmp2_reg));
+        } else {
+            EMIT(PPC_RAW_STD(src_reg, tmp1_reg, off));
+        }
+        break;
+    default:
+        return -EINVAL;
+    }
+    return 0;
+}
+
  static int emit_atomic_ld_st(const struct bpf_insn insn,
struct codegen_context *ctx, u32 *image)
  {
      u32 code = insn.code;