bpf: Use arch_bpf_trampoline_size

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Instead of blindly allocating PAGE_SIZE for each trampoline, check the size
of the trampoline with arch_bpf_trampoline_size(). This size is saved in
bpf_tramp_image->size, and used for modmem charge/uncharge. The fallback
arch_alloc_bpf_trampoline() still allocates a whole page because we need to
use set_memory_* to protect the memory.

struct_ops trampoline still uses a whole page for multiple trampolines.

With this size check at caller (regular trampoline and struct_ops
trampoline), remove arch_bpf_trampoline_size() from
arch_prepare_bpf_trampoline() in archs.

Also, update bpf_image_ksym_add() to handle symbol of different sizes.

Signed-off-by: Song Liu <song@kernel.org>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>  # on s390x
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Björn Töpel <bjorn@rivosinc.com> # on riscv
Link: https://lore.kernel.org/r/20231206224054.492250-7-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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This commit is contained in:

Song Liu 2023-12-06 14:40:53 -08:00 • committed by Alexei Starovoitov

parent 96d1b7c081

commit 26ef208c20

6 changed files with 44 additions and 37 deletions

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7

arch/arm64/net/bpf_jit_comp.c

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7

arch/riscv/net/bpf_jit_comp64.c

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3

include/linux/bpf.h

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7

kernel/bpf/bpf_struct_ops.c

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2

kernel/bpf/dispatcher.c

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55

kernel/bpf/trampoline.c

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