On Wed, Jun 12, 2024 at 8:32 AM Maxwell Bland <mbland@xxxxxxxxxxxx> wrote:
>
> Corrects Puranjay Mohan's commit to adopt Mark Rutland's
> suggestion of using a C CFI type macro in kCFI+BPF.
>
> Signed-off-by: Maxwell Bland <mbland@xxxxxxxxxxxx>
> ---
> arch/arm64/kernel/alternative.c | 46 ++++-----------------------------
> 1 file changed, 5 insertions(+), 41 deletions(-)
>
> diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
> index 1715da7df137..d7a58eca7665 100644
> --- a/arch/arm64/kernel/alternative.c
> +++ b/arch/arm64/kernel/alternative.c
> @@ -8,6 +8,7 @@
>
> #define pr_fmt(fmt) "alternatives: " fmt
>
> +#include <linux/cfi_types.h>
> #include <linux/init.h>
> #include <linux/cpu.h>
> #include <linux/elf.h>
> @@ -302,53 +303,16 @@ EXPORT_SYMBOL(alt_cb_patch_nops);
>
> #ifdef CONFIG_CFI_CLANG
> struct bpf_insn;
> -
> /* Must match bpf_func_t / DEFINE_BPF_PROG_RUN() */
> extern unsigned int __bpf_prog_runX(const void *ctx,
> const struct bpf_insn *insn);
> -
> -/*
> - * Force a reference to the external symbol so the compiler generates
> - * __kcfi_typid.
> - */
> -__ADDRESSABLE(__bpf_prog_runX);
> -
> -/* u32 __ro_after_init cfi_bpf_hash = __kcfi_typeid___bpf_prog_runX; */
> -asm (
> -" .pushsection .data..ro_after_init,\"aw\",@progbits \n"
> -" .type cfi_bpf_hash,@object \n"
> -" .globl cfi_bpf_hash \n"
> -" .p2align 2, 0x0 \n"
> -"cfi_bpf_hash: \n"
> -" .word __kcfi_typeid___bpf_prog_runX \n"
> -" .size cfi_bpf_hash, 4 \n"
> -" .popsection \n"
> -);
> -
> +DEFINE_CFI_TYPE(cfi_bpf_hash, __bpf_prog_runX);
> /* Must match bpf_callback_t */
> extern u64 __bpf_callback_fn(u64, u64, u64, u64, u64);
> -
> -__ADDRESSABLE(__bpf_callback_fn);
> -
> -/* u32 __ro_after_init cfi_bpf_subprog_hash = __kcfi_typeid___bpf_callback_fn; */
> -asm (
> -" .pushsection .data..ro_after_init,\"aw\",@progbits \n"
> -" .type cfi_bpf_subprog_hash,@object \n"
> -" .globl cfi_bpf_subprog_hash \n"
> -" .p2align 2, 0x0 \n"
> -"cfi_bpf_subprog_hash: \n"
> -" .word __kcfi_typeid___bpf_callback_fn \n"
> -" .size cfi_bpf_subprog_hash, 4 \n"
> -" .popsection \n"
> -);
> -
> +DEFINE_CFI_TYPE(cfi_bpf_subprog_hash, __bpf_callback_fn);
> u32 cfi_get_func_hash(void *func)
> {
> - u32 hash;
> -
> - if (get_kernel_nofault(hash, func - cfi_get_offset()))
> - return 0;
> -
> - return hash;
> + u32 *hashp = func - cfi_get_offset();
> + return READ_ONCE(*hashp);
Please avoid the code churn.
Just squash it into the previous patch.
pw-bot: cr
