On Thu, Mar 9, 2023 at 10:02 AM Hari Bathini <hbathini@xxxxxxxxxxxxx> wrote:
>
> bpf_arch_text_copy is used to dump JITed binary to RX page, allowing
> multiple BPF programs to share the same page. Use the newly introduced
> patch_instructions() to implement it. Around 5X improvement in speed
> of execution observed, using the new patch_instructions() function
> over patch_instruction(), while running the tests from test_bpf.ko.
>
> Signed-off-by: Hari Bathini <hbathini@xxxxxxxxxxxxx>
> ---
> arch/powerpc/net/bpf_jit_comp.c | 23 ++++++++++++++++++++++-
> 1 file changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
> index e93aefcfb83f..0a70319116d1 100644
> --- a/arch/powerpc/net/bpf_jit_comp.c
> +++ b/arch/powerpc/net/bpf_jit_comp.c
> @@ -13,9 +13,12 @@
> #include <linux/netdevice.h>
> #include <linux/filter.h>
> #include <linux/if_vlan.h>
> -#include <asm/kprobes.h>
> +#include <linux/memory.h>
> #include <linux/bpf.h>
>
> +#include <asm/kprobes.h>
> +#include <asm/code-patching.h>
> +
> #include "bpf_jit.h"
>
> static void bpf_jit_fill_ill_insns(void *area, unsigned int size)
> @@ -272,3 +275,21 @@ int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, int pass, struct code
> ctx->exentry_idx++;
> return 0;
> }
> +
> +void *bpf_arch_text_copy(void *dst, void *src, size_t len)
> +{
> + void *ret = ERR_PTR(-EINVAL);
> + int err;
> +
> + if (WARN_ON_ONCE(core_kernel_text((unsigned long)dst)))
> + return ret;
> +
> + ret = dst;
> + mutex_lock(&text_mutex);
> + err = patch_instructions(dst, src, false, len);
> + if (err)
> + ret = ERR_PTR(err);
> + mutex_unlock(&text_mutex);
> +
> + return ret;
> +}
It seems we don't really need "ret". How about something like:
+void *bpf_arch_text_copy(void *dst, void *src, size_t len)
+{
+ int err;
+
+ if (WARN_ON_ONCE(core_kernel_text((unsigned long)dst)))
+ return ERR_PTR(-EINVAL);
+
+ mutex_lock(&text_mutex);
+ err = patch_instructions(dst, src, false, len);
+ mutex_unlock(&text_mutex);
+
+ return err ? ERR_PTR(err) : dst;
+}
Song
