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-rw-r--r--arch/x86/net/bpf_jit_comp.c57
1 files changed, 25 insertions, 32 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index df484885cc..f415c2cf53 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1585,36 +1585,41 @@ st: if (is_imm8(insn->off))
if (BPF_MODE(insn->code) == BPF_PROBE_MEM ||
BPF_MODE(insn->code) == BPF_PROBE_MEMSX) {
/* Conservatively check that src_reg + insn->off is a kernel address:
- * src_reg + insn->off >= TASK_SIZE_MAX + PAGE_SIZE
- * src_reg is used as scratch for src_reg += insn->off and restored
- * after emit_ldx if necessary
+ * src_reg + insn->off > TASK_SIZE_MAX + PAGE_SIZE
+ * and
+ * src_reg + insn->off < VSYSCALL_ADDR
*/
- u64 limit = TASK_SIZE_MAX + PAGE_SIZE;
+ u64 limit = TASK_SIZE_MAX + PAGE_SIZE - VSYSCALL_ADDR;
u8 *end_of_jmp;
- /* At end of these emitted checks, insn->off will have been added
- * to src_reg, so no need to do relative load with insn->off offset
- */
- insn_off = 0;
+ /* movabsq r10, VSYSCALL_ADDR */
+ emit_mov_imm64(&prog, BPF_REG_AX, (long)VSYSCALL_ADDR >> 32,
+ (u32)(long)VSYSCALL_ADDR);
- /* movabsq r11, limit */
- EMIT2(add_1mod(0x48, AUX_REG), add_1reg(0xB8, AUX_REG));
- EMIT((u32)limit, 4);
- EMIT(limit >> 32, 4);
+ /* mov src_reg, r11 */
+ EMIT_mov(AUX_REG, src_reg);
if (insn->off) {
- /* add src_reg, insn->off */
- maybe_emit_1mod(&prog, src_reg, true);
- EMIT2_off32(0x81, add_1reg(0xC0, src_reg), insn->off);
+ /* add r11, insn->off */
+ maybe_emit_1mod(&prog, AUX_REG, true);
+ EMIT2_off32(0x81, add_1reg(0xC0, AUX_REG), insn->off);
}
- /* cmp src_reg, r11 */
- maybe_emit_mod(&prog, src_reg, AUX_REG, true);
- EMIT2(0x39, add_2reg(0xC0, src_reg, AUX_REG));
+ /* sub r11, r10 */
+ maybe_emit_mod(&prog, AUX_REG, BPF_REG_AX, true);
+ EMIT2(0x29, add_2reg(0xC0, AUX_REG, BPF_REG_AX));
+
+ /* movabsq r10, limit */
+ emit_mov_imm64(&prog, BPF_REG_AX, (long)limit >> 32,
+ (u32)(long)limit);
+
+ /* cmp r10, r11 */
+ maybe_emit_mod(&prog, AUX_REG, BPF_REG_AX, true);
+ EMIT2(0x39, add_2reg(0xC0, AUX_REG, BPF_REG_AX));
- /* if unsigned '>=', goto load */
- EMIT2(X86_JAE, 0);
+ /* if unsigned '>', goto load */
+ EMIT2(X86_JA, 0);
end_of_jmp = prog;
/* xor dst_reg, dst_reg */
@@ -1640,18 +1645,6 @@ st: if (is_imm8(insn->off))
/* populate jmp_offset for JMP above */
start_of_ldx[-1] = prog - start_of_ldx;
- if (insn->off && src_reg != dst_reg) {
- /* sub src_reg, insn->off
- * Restore src_reg after "add src_reg, insn->off" in prev
- * if statement. But if src_reg == dst_reg, emit_ldx
- * above already clobbered src_reg, so no need to restore.
- * If add src_reg, insn->off was unnecessary, no need to
- * restore either.
- */
- maybe_emit_1mod(&prog, src_reg, true);
- EMIT2_off32(0x81, add_1reg(0xE8, src_reg), insn->off);
- }
-
if (!bpf_prog->aux->extable)
break;