sparc: bpf_jit: fix loads from negative offsets
- fix BPF_LD|ABS|IND from negative offsets:
make sure to sign extend lower 32 bits in 64-bit register
before calling C helpers from JITed code, otherwise 'int k'
argument of bpf_internal_load_pointer_neg_helper() function
will be added as large unsigned integer, causing packet size
check to trigger and abort the program.
It's worth noting that JITed code for 'A = A op K' will affect
upper 32 bits differently depending whether K is simm13 or not.
Since small constants are sign extended, whereas large constants
are stored in temp register and zero extended.
That is ok and we don't have to pay a penalty of sign extension
for every sethi, since all classic BPF instructions have 32-bit
semantics and we only need to set correct upper bits when
transitioning from JITed code into C.
- though instructions 'A &= 0' and 'A *= 0' are odd, JIT compiler
should not optimize them out
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/net/bpf_jit_comp.c b/arch/sparc/net/bpf_jit_comp.c
index 51ae87b..ece4af0 100644
--- a/arch/sparc/net/bpf_jit_comp.c
+++ b/arch/sparc/net/bpf_jit_comp.c
@@ -184,7 +184,7 @@
*/
#define emit_alu_K(OPCODE, K) \
do { \
- if (K) { \
+ if (K || OPCODE == AND || OPCODE == MUL) { \
unsigned int _insn = OPCODE; \
_insn |= RS1(r_A) | RD(r_A); \
if (is_simm13(K)) { \