bpf: take advantage of stack_depth tracking in powerpc JIT

Take advantage of stack_depth tracking, originally introduced for
x64, in powerpc JIT as well. Round up allocated stack by 16 bytes
to make sure it stays aligned for functions called from JITed bpf
program.

Signed-off-by: Sandipan Das <sandipan@linux.vnet.ibm.com>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/net/bpf_jit64.h b/arch/powerpc/net/bpf_jit64.h
index 62fa7589db2b4edc6e9e28742a4b7e531fd23162..8bdef7ed28a831353d1d6b17499f54f439aff191 100644 (file)
--- a/arch/powerpc/net/bpf_jit64.h
+++ b/arch/powerpc/net/bpf_jit64.h
@@ -23,7 +23,7 @@
  *             [   nv gpr save area    ] 8*8           |
  *             [    tail_call_cnt      ] 8             |
  *             [    local_tmp_var      ] 8             |
- * fp (r31) -->        [   ebpf stack space    ] 512           |
+ * fp (r31) -->        [   ebpf stack space    ] upto 512      |
  *             [     frame header      ] 32/112        |
  * sp (r1) --->        [    stack pointer      ] --------------
  */
@@ -32,8 +32,8 @@
 #define BPF_PPC_STACK_SAVE     (8*8)
 /* for bpf JIT code internal usage */
 #define BPF_PPC_STACK_LOCALS   16
-/* Ensure this is quadword aligned */
-#define BPF_PPC_STACKFRAME     (STACK_FRAME_MIN_SIZE + MAX_BPF_STACK + \
+/* stack frame excluding BPF stack, ensure this is quadword aligned */
+#define BPF_PPC_STACKFRAME     (STACK_FRAME_MIN_SIZE + \
                                 BPF_PPC_STACK_LOCALS + BPF_PPC_STACK_SAVE)
 
 #ifndef __ASSEMBLY__
@@ -103,6 +103,7 @@ struct codegen_context {
         */
        unsigned int seen;
        unsigned int idx;
+       unsigned int stack_size;
 };
 
 #endif /* !__ASSEMBLY__ */

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index a66e64b0b251f7853722333ba3559ff556ceabc4..46d74e81aff1b4caad4769e7686fa0a800695cd4 100644 (file)
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -69,7 +69,7 @@ static inline bool bpf_has_stack_frame(struct codegen_context *ctx)
 static int bpf_jit_stack_local(struct codegen_context *ctx)
 {
        if (bpf_has_stack_frame(ctx))
-               return STACK_FRAME_MIN_SIZE + MAX_BPF_STACK;
+               return STACK_FRAME_MIN_SIZE + ctx->stack_size;
        else
                return -(BPF_PPC_STACK_SAVE + 16);
 }
@@ -82,8 +82,9 @@ static int bpf_jit_stack_tailcallcnt(struct codegen_context *ctx)
 static int bpf_jit_stack_offsetof(struct codegen_context *ctx, int reg)
 {
        if (reg >= BPF_PPC_NVR_MIN && reg < 32)
-               return (bpf_has_stack_frame(ctx) ? BPF_PPC_STACKFRAME : 0)
-                                                       - (8 * (32 - reg));
+               return (bpf_has_stack_frame(ctx) ?
+                       (BPF_PPC_STACKFRAME + ctx->stack_size) : 0)
+                               - (8 * (32 - reg));
 
        pr_err("BPF JIT is asking about unknown registers");
        BUG();
@@ -134,7 +135,7 @@ static void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx)
                        PPC_BPF_STL(0, 1, PPC_LR_STKOFF);
                }
 
-               PPC_BPF_STLU(1, 1, -BPF_PPC_STACKFRAME);
+               PPC_BPF_STLU(1, 1, -(BPF_PPC_STACKFRAME + ctx->stack_size));
        }
 
        /*
@@ -161,7 +162,7 @@ static void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx)
        /* Setup frame pointer to point to the bpf stack area */
        if (bpf_is_seen_register(ctx, BPF_REG_FP))
                PPC_ADDI(b2p[BPF_REG_FP], 1,
-                               STACK_FRAME_MIN_SIZE + MAX_BPF_STACK);
+                               STACK_FRAME_MIN_SIZE + ctx->stack_size);
 }
 
 static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx)
@@ -183,7 +184,7 @@ static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx
 
        /* Tear down our stack frame */
        if (bpf_has_stack_frame(ctx)) {
-               PPC_ADDI(1, 1, BPF_PPC_STACKFRAME);
+               PPC_ADDI(1, 1, BPF_PPC_STACKFRAME + ctx->stack_size);
                if (ctx->seen & SEEN_FUNC) {
                        PPC_BPF_LL(0, 1, PPC_LR_STKOFF);
                        PPC_MTLR(0);
@@ -1013,6 +1014,9 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
 
        memset(&cgctx, 0, sizeof(struct codegen_context));
 
+       /* Make sure that the stack is quadword aligned. */
+       cgctx.stack_size = round_up(fp->aux->stack_depth, 16);
+
        /* Scouting faux-generate pass 0 */
        if (bpf_jit_build_body(fp, 0, &cgctx, addrs)) {
                /* We hit something illegal or unsupported. */