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selftests/bpf: add verifier sign extension bound computation tests.

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This commit adds 3 tests to verify a common compiler generated
pattern for sign extension (r1 <<= 32; r1 s>>= 32).
The tests make sure the register bounds are correctly computed both for
positive and negative register values.

Signed-off-by: Cupertino Miranda  <cupertino.miranda@oracle.com>
Signed-off-by: Andrew Pinski  <andrew.pinski@oss.qualcomm.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Cc: David Faust  <david.faust@oracle.com>
Cc: Jose Marchesi  <jose.marchesi@oracle.com>
Cc: Elena Zannoni  <elena.zannoni@oracle.com>
Link: https://lore.kernel.org/r/20251202180220.11128-3-cupertino.miranda@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Cupertino Miranda 2025-12-02 18:02:20 +00:00 committed by Alexei Starovoitov
parent d18dec4b89
commit a5b4867fad
1 changed files with 68 additions and 0 deletions
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68
tools/testing/selftests/bpf/progs/verifier_subreg.c
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@ -531,6 +531,74 @@ __naked void arsh32_imm_zero_extend_check(void)
: __clobber_all);
}
SEC("socket")
__description("arsh32 imm sign positive extend check")
__success __retval(0)
__log_level(2)
__msg("2: (57) r6 &= 4095 ; R6=scalar(smin=smin32=0,smax=umax=smax32=umax32=4095,var_off=(0x0; 0xfff))")
__msg("3: (67) r6 <<= 32 ; R6=scalar(smin=smin32=0,smax=umax=0xfff00000000,smax32=umax32=0,var_off=(0x0; 0xfff00000000))")
__msg("4: (c7) r6 s>>= 32 ; R6=scalar(smin=smin32=0,smax=umax=smax32=umax32=4095,var_off=(0x0; 0xfff))")
__naked void arsh32_imm_sign_extend_positive_check(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r6 = r0; \
r6 &= 4095; \
r6 <<= 32; \
r6 s>>= 32; \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
SEC("socket")
__description("arsh32 imm sign negative extend check")
__success __retval(0)
__log_level(2)
__msg("3: (17) r6 -= 4095 ; R6=scalar(smin=smin32=-4095,smax=smax32=0)")
__msg("4: (67) r6 <<= 32 ; R6=scalar(smin=0xfffff00100000000,smax=smax32=umax32=0,umax=0xffffffff00000000,smin32=0,var_off=(0x0; 0xffffffff00000000))")
__msg("5: (c7) r6 s>>= 32 ; R6=scalar(smin=smin32=-4095,smax=smax32=0)")
__naked void arsh32_imm_sign_extend_negative_check(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r6 = r0; \
r6 &= 4095; \
r6 -= 4095; \
r6 <<= 32; \
r6 s>>= 32; \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
SEC("socket")
__description("arsh32 imm sign extend check")
__success __retval(0)
__log_level(2)
__msg("3: (17) r6 -= 2047 ; R6=scalar(smin=smin32=-2047,smax=smax32=2048)")
__msg("4: (67) r6 <<= 32 ; R6=scalar(smin=0xfffff80100000000,smax=0x80000000000,umax=0xffffffff00000000,smin32=0,smax32=umax32=0,var_off=(0x0; 0xffffffff00000000))")
__msg("5: (c7) r6 s>>= 32 ; R6=scalar(smin=smin32=-2047,smax=smax32=2048)")
__naked void arsh32_imm_sign_extend_check(void)
{
asm volatile (" \
call %[bpf_get_prandom_u32]; \
r6 = r0; \
r6 &= 4095; \
r6 -= 2047; \
r6 <<= 32; \
r6 s>>= 32; \
r0 = 0; \
exit; \
" :
: __imm(bpf_get_prandom_u32)
: __clobber_all);
}
SEC("socket")
__description("end16 (to_le) reg zero extend check")
__success __success_unpriv __retval(0)