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bpf: Add helper macro bpf_addr_space_cast()

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Introduce helper macro bpf_addr_space_cast() that emits:
rX = rX
instruction with off = BPF_ADDR_SPACE_CAST
and encodes dest and src address_space-s into imm32.

It's useful with older LLVM that doesn't emit this insn automatically.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20240308010812.89848-12-alexei.starovoitov@gmail.com
This commit is contained in:
Alexei Starovoitov 2024-03-07 17:08:09 -08:00 committed by Andrii Nakryiko
parent 2e7ba4f8fd
commit 204c628730
1 changed files with 43 additions and 0 deletions
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43
tools/testing/selftests/bpf/bpf_experimental.h
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@ -343,6 +343,49 @@ l_true: \
asm volatile("%[reg]=%[reg]"::[reg]"r"((short)var))
#endif
/* emit instruction:
* rX = rX .off = BPF_ADDR_SPACE_CAST .imm32 = (dst_as << 16) | src_as
*/
#ifndef bpf_addr_space_cast
#define bpf_addr_space_cast(var, dst_as, src_as)\
asm volatile(".byte 0xBF; \
.ifc %[reg], r0; \
.byte 0x00; \
.endif; \
.ifc %[reg], r1; \
.byte 0x11; \
.endif; \
.ifc %[reg], r2; \
.byte 0x22; \
.endif; \
.ifc %[reg], r3; \
.byte 0x33; \
.endif; \
.ifc %[reg], r4; \
.byte 0x44; \
.endif; \
.ifc %[reg], r5; \
.byte 0x55; \
.endif; \
.ifc %[reg], r6; \
.byte 0x66; \
.endif; \
.ifc %[reg], r7; \
.byte 0x77; \
.endif; \
.ifc %[reg], r8; \
.byte 0x88; \
.endif; \
.ifc %[reg], r9; \
.byte 0x99; \
.endif; \
.short %[off]; \
.long %[as]" \
: [reg]"+r"(var) \
: [off]"i"(BPF_ADDR_SPACE_CAST) \
, [as]"i"((dst_as << 16) | src_as));
#endif
/* Description
* Assert that a conditional expression is true.
* Returns