On 2017/09/02 12:23AM, Sandipan Das wrote:
> 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 <sandi...@linux.vnet.ibm.com>
> ---
LGTM, thanks!
Reviewed-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
Michael,
Seeing as this is powerpc specific, can you please take this through
your tree?
Thanks,
Naveen
> arch/powerpc/net/bpf_jit64.h | 7 ++++---
> arch/powerpc/net/bpf_jit_comp64.c | 16 ++++++++++------
> 2 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/net/bpf_jit64.h b/arch/powerpc/net/bpf_jit64.h
> index 62fa7589db2b..8bdef7ed28a8 100644
> --- 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 6ba5d253e857..a01362c88f6a 100644
> --- 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);
> @@ -993,6 +994,9 @@ 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. */
> --
> 2.13.5
>
