selftests: bpf: Add tests for signed loads from arena

Add tests for loading 8, 16, and 32 bits with sign extension from arena,
also verify that exception handling is working correctly and correct
assembly is being generated by the x86 and arm64 JITs.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20250923110157.18326-4-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 176 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/verifier_ldsx.c b/tools/testing/selftests/bpf/progs/verifier_ldsx.c
index f087ffb79f20..c8494b682c31 100644
--- a/tools/testing/selftests/bpf/progs/verifier_ldsx.c
+++ b/tools/testing/selftests/bpf/progs/verifier_ldsx.c
@@ -3,6 +3,7 @@
 #include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 #include "bpf_misc.h"
+#include "bpf_arena_common.h"
 
 #if (defined(__TARGET_ARCH_arm64) || defined(__TARGET_ARCH_x86) || \
 	(defined(__TARGET_ARCH_riscv) && __riscv_xlen == 64) || \
@@ -10,6 +11,12 @@
 	defined(__TARGET_ARCH_loongarch)) && \
 	__clang_major__ >= 18
 
+struct {
+	__uint(type, BPF_MAP_TYPE_ARENA);
+	__uint(map_flags, BPF_F_MMAPABLE);
+	__uint(max_entries, 1);
+} arena SEC(".maps");
+
 SEC("socket")
 __description("LDSX, S8")
 __success __success_unpriv __retval(-2)
@@ -256,6 +263,175 @@ __naked void ldsx_ctx_8(void)
 	: __clobber_all);
 }
 
+SEC("syscall")
+__description("Arena LDSX Disasm")
+__success
+__arch_x86_64
+__jited("movslq	0x10(%rax,%r12), %r14")
+__jited("movswq	0x18(%rax,%r12), %r14")
+__jited("movsbq	0x20(%rax,%r12), %r14")
+__jited("movslq	0x10(%rdi,%r12), %r15")
+__jited("movswq	0x18(%rdi,%r12), %r15")
+__jited("movsbq	0x20(%rdi,%r12), %r15")
+__arch_arm64
+__jited("add	x11, x7, x28")
+__jited("ldrsw	x21, [x11, #0x10]")
+__jited("add	x11, x7, x28")
+__jited("ldrsh	x21, [x11, #0x18]")
+__jited("add	x11, x7, x28")
+__jited("ldrsb	x21, [x11, #0x20]")
+__jited("add	x11, x0, x28")
+__jited("ldrsw	x22, [x11, #0x10]")
+__jited("add	x11, x0, x28")
+__jited("ldrsh	x22, [x11, #0x18]")
+__jited("add	x11, x0, x28")
+__jited("ldrsb	x22, [x11, #0x20]")
+__naked void arena_ldsx_disasm(void *ctx)
+{
+	asm volatile (
+	"r1 = %[arena] ll;"
+	"r2 = 0;"
+	"r3 = 1;"
+	"r4 = %[numa_no_node];"
+	"r5 = 0;"
+	"call %[bpf_arena_alloc_pages];"
+	"r0 = addr_space_cast(r0, 0x0, 0x1);"
+	"r1 = r0;"
+	"r8 = *(s32 *)(r0 + 16);"
+	"r8 = *(s16 *)(r0 + 24);"
+	"r8 = *(s8  *)(r0 + 32);"
+	"r9 = *(s32 *)(r1 + 16);"
+	"r9 = *(s16 *)(r1 + 24);"
+	"r9 = *(s8  *)(r1 + 32);"
+	"r0 = 0;"
+	"exit;"
+	:: __imm(bpf_arena_alloc_pages),
+	   __imm_addr(arena),
+	   __imm_const(numa_no_node, NUMA_NO_NODE)
+	:  __clobber_all
+	);
+}
+
+SEC("syscall")
+__description("Arena LDSX Exception")
+__success __retval(0)
+__arch_x86_64
+__arch_arm64
+__naked void arena_ldsx_exception(void *ctx)
+{
+	asm volatile (
+	"r1 = %[arena] ll;"
+	"r0 = 0xdeadbeef;"
+	"r0 = addr_space_cast(r0, 0x0, 0x1);"
+	"r1 = 0x3fe;"
+	"*(u64 *)(r0 + 0) = r1;"
+	"r0 = *(s8 *)(r0 + 0);"
+	"exit;"
+	:
+	:  __imm_addr(arena)
+	:  __clobber_all
+	);
+}
+
+SEC("syscall")
+__description("Arena LDSX, S8")
+__success __retval(-1)
+__arch_x86_64
+__arch_arm64
+__naked void arena_ldsx_s8(void *ctx)
+{
+	asm volatile (
+	"r1 = %[arena] ll;"
+	"r2 = 0;"
+	"r3 = 1;"
+	"r4 = %[numa_no_node];"
+	"r5 = 0;"
+	"call %[bpf_arena_alloc_pages];"
+	"r0 = addr_space_cast(r0, 0x0, 0x1);"
+	"r1 = 0x3fe;"
+	"*(u64 *)(r0 + 0) = r1;"
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	"r0 = *(s8 *)(r0 + 0);"
+#else
+	"r0 = *(s8 *)(r0 + 7);"
+#endif
+	"r0 >>= 1;"
+	"exit;"
+	:: __imm(bpf_arena_alloc_pages),
+	   __imm_addr(arena),
+	   __imm_const(numa_no_node, NUMA_NO_NODE)
+	:  __clobber_all
+	);
+}
+
+SEC("syscall")
+__description("Arena LDSX, S16")
+__success __retval(-1)
+__arch_x86_64
+__arch_arm64
+__naked void arena_ldsx_s16(void *ctx)
+{
+	asm volatile (
+	"r1 = %[arena] ll;"
+	"r2 = 0;"
+	"r3 = 1;"
+	"r4 = %[numa_no_node];"
+	"r5 = 0;"
+	"call %[bpf_arena_alloc_pages];"
+	"r0 = addr_space_cast(r0, 0x0, 0x1);"
+	"r1 = 0x3fffe;"
+	"*(u64 *)(r0 + 0) = r1;"
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	"r0 = *(s16 *)(r0 + 0);"
+#else
+	"r0 = *(s16 *)(r0 + 6);"
+#endif
+	"r0 >>= 1;"
+	"exit;"
+	:: __imm(bpf_arena_alloc_pages),
+	   __imm_addr(arena),
+	   __imm_const(numa_no_node, NUMA_NO_NODE)
+	:  __clobber_all
+	);
+}
+
+SEC("syscall")
+__description("Arena LDSX, S32")
+__success __retval(-1)
+__arch_x86_64
+__arch_arm64
+__naked void arena_ldsx_s32(void *ctx)
+{
+	asm volatile (
+	"r1 = %[arena] ll;"
+	"r2 = 0;"
+	"r3 = 1;"
+	"r4 = %[numa_no_node];"
+	"r5 = 0;"
+	"call %[bpf_arena_alloc_pages];"
+	"r0 = addr_space_cast(r0, 0x0, 0x1);"
+	"r1 = 0xfffffffe;"
+	"*(u64 *)(r0 + 0) = r1;"
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	"r0 = *(s32 *)(r0 + 0);"
+#else
+	"r0 = *(s32 *)(r0 + 4);"
+#endif
+	"r0 >>= 1;"
+	"exit;"
+	:: __imm(bpf_arena_alloc_pages),
+	   __imm_addr(arena),
+	   __imm_const(numa_no_node, NUMA_NO_NODE)
+	:  __clobber_all
+	);
+}
+
+/* to retain debug info for BTF generation */
+void kfunc_root(void)
+{
+	bpf_arena_alloc_pages(0, 0, 0, 0, 0);
+}
+
 #else
 
 SEC("socket")