selftests/bpf: Test assigning ID to scalars on spill

The previous commit implemented assigning IDs to registers holding
scalars before spill. Add the test cases to check the new functionality.

Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240108205209.838365-10-maxtram95@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
index f303ac19cf410065bde3c6ffee3c12555c87ce27..b05aab925ee572c993c3f11eaac3e613b80c15ff 100644 (file)
--- a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
+++ b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
@@ -766,4 +766,137 @@ l0_%=:    r0 = 0;                                         \
        : __clobber_all);
 }
 
+SEC("xdp")
+__description("64-bit spill of 64-bit reg should assign ID")
+__success __retval(0)
+__naked void spill_64bit_of_64bit_ok(void)
+{
+       asm volatile ("                                 \
+       /* Roll one bit to make the register inexact. */\
+       call %[bpf_get_prandom_u32];                    \
+       r0 &= 0x80000000;                               \
+       r0 <<= 32;                                      \
+       /* 64-bit spill r0 to stack - should assign an ID. */\
+       *(u64*)(r10 - 8) = r0;                          \
+       /* 64-bit fill r1 from stack - should preserve the ID. */\
+       r1 = *(u64*)(r10 - 8);                          \
+       /* Compare r1 with another register to trigger find_equal_scalars.\
+        * Having one random bit is important here, otherwise the verifier cuts\
+        * the corners.                                 \
+        */                                             \
+       r2 = 0;                                         \
+       if r1 != r2 goto l0_%=;                         \
+       /* The result of this comparison is predefined. */\
+       if r0 == r2 goto l0_%=;                         \
+       /* Dead branch: the verifier should prune it. Do an invalid memory\
+        * access if the verifier follows it.           \
+        */                                             \
+       r0 = *(u64*)(r9 + 0);                           \
+       exit;                                           \
+l0_%=: r0 = 0;                                         \
+       exit;                                           \
+"      :
+       : __imm(bpf_get_prandom_u32)
+       : __clobber_all);
+}
+
+SEC("xdp")
+__description("32-bit spill of 32-bit reg should assign ID")
+__success __retval(0)
+__naked void spill_32bit_of_32bit_ok(void)
+{
+       asm volatile ("                                 \
+       /* Roll one bit to make the register inexact. */\
+       call %[bpf_get_prandom_u32];                    \
+       w0 &= 0x80000000;                               \
+       /* 32-bit spill r0 to stack - should assign an ID. */\
+       *(u32*)(r10 - 8) = r0;                          \
+       /* 32-bit fill r1 from stack - should preserve the ID. */\
+       r1 = *(u32*)(r10 - 8);                          \
+       /* Compare r1 with another register to trigger find_equal_scalars.\
+        * Having one random bit is important here, otherwise the verifier cuts\
+        * the corners.                                 \
+        */                                             \
+       r2 = 0;                                         \
+       if r1 != r2 goto l0_%=;                         \
+       /* The result of this comparison is predefined. */\
+       if r0 == r2 goto l0_%=;                         \
+       /* Dead branch: the verifier should prune it. Do an invalid memory\
+        * access if the verifier follows it.           \
+        */                                             \
+       r0 = *(u64*)(r9 + 0);                           \
+       exit;                                           \
+l0_%=: r0 = 0;                                         \
+       exit;                                           \
+"      :
+       : __imm(bpf_get_prandom_u32)
+       : __clobber_all);
+}
+
+SEC("xdp")
+__description("16-bit spill of 16-bit reg should assign ID")
+__success __retval(0)
+__naked void spill_16bit_of_16bit_ok(void)
+{
+       asm volatile ("                                 \
+       /* Roll one bit to make the register inexact. */\
+       call %[bpf_get_prandom_u32];                    \
+       r0 &= 0x8000;                                   \
+       /* 16-bit spill r0 to stack - should assign an ID. */\
+       *(u16*)(r10 - 8) = r0;                          \
+       /* 16-bit fill r1 from stack - should preserve the ID. */\
+       r1 = *(u16*)(r10 - 8);                          \
+       /* Compare r1 with another register to trigger find_equal_scalars.\
+        * Having one random bit is important here, otherwise the verifier cuts\
+        * the corners.                                 \
+        */                                             \
+       r2 = 0;                                         \
+       if r1 != r2 goto l0_%=;                         \
+       /* The result of this comparison is predefined. */\
+       if r0 == r2 goto l0_%=;                         \
+       /* Dead branch: the verifier should prune it. Do an invalid memory\
+        * access if the verifier follows it.           \
+        */                                             \
+       r0 = *(u64*)(r9 + 0);                           \
+       exit;                                           \
+l0_%=: r0 = 0;                                         \
+       exit;                                           \
+"      :
+       : __imm(bpf_get_prandom_u32)
+       : __clobber_all);
+}
+
+SEC("xdp")
+__description("8-bit spill of 8-bit reg should assign ID")
+__success __retval(0)
+__naked void spill_8bit_of_8bit_ok(void)
+{
+       asm volatile ("                                 \
+       /* Roll one bit to make the register inexact. */\
+       call %[bpf_get_prandom_u32];                    \
+       r0 &= 0x80;                                     \
+       /* 8-bit spill r0 to stack - should assign an ID. */\
+       *(u8*)(r10 - 8) = r0;                           \
+       /* 8-bit fill r1 from stack - should preserve the ID. */\
+       r1 = *(u8*)(r10 - 8);                           \
+       /* Compare r1 with another register to trigger find_equal_scalars.\
+        * Having one random bit is important here, otherwise the verifier cuts\
+        * the corners.                                 \
+        */                                             \
+       r2 = 0;                                         \
+       if r1 != r2 goto l0_%=;                         \
+       /* The result of this comparison is predefined. */\
+       if r0 == r2 goto l0_%=;                         \
+       /* Dead branch: the verifier should prune it. Do an invalid memory\
+        * access if the verifier follows it.           \
+        */                                             \
+       r0 = *(u64*)(r9 + 0);                           \
+       exit;                                           \
+l0_%=: r0 = 0;                                         \
+       exit;                                           \
+"      :
+       : __imm(bpf_get_prandom_u32)
+       : __clobber_all);
+}
+
 char _license[] SEC("license") = "GPL";