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authorDavid S. Miller <davem@davemloft.net>2012-04-17 16:38:16 -0400
committerDavid S. Miller <davem@davemloft.net>2012-04-17 16:43:46 -0400
commit584c5e2ad3ada1a5ccfffa68347b79c3681cc36e (patch)
tree462835521cf30f6ceb29471bc2cb6cf37dd9bc94 /arch/sparc/net
parent7b56f76edf2da7ab3e356cc0db16f9af4c6a26e2 (diff)
downloadlinux-584c5e2ad3ada1a5ccfffa68347b79c3681cc36e.tar.gz
net: filter: Fix some more small issues in sparc JIT.
Fix mixed space and tabs. Put bpf_jit_load_*[] externs into bpf_jit.h "while(0)" --> "while (0)" "COND (X)" --> "COND(X)" Document branch offset calculations, and bpf_error's return sequence. Document the reason we need to emit three nops between the %y register write and the divide instruction. Remove erroneous trailing semicolons from emit_read_y() and emit_write_y(). Based upon feedback from Sam Ravnborg. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/sparc/net')
-rw-r--r--arch/sparc/net/bpf_jit.h15
-rw-r--r--arch/sparc/net/bpf_jit_asm.S6
-rw-r--r--arch/sparc/net/bpf_jit_comp.c107
3 files changed, 84 insertions, 44 deletions
diff --git a/arch/sparc/net/bpf_jit.h b/arch/sparc/net/bpf_jit.h
index 05175be442fb..33d6b375ff12 100644
--- a/arch/sparc/net/bpf_jit.h
+++ b/arch/sparc/net/bpf_jit.h
@@ -38,6 +38,21 @@
#define r_TMP G1
#define r_TMP2 G2
#define r_OFF G3
+
+/* assembly code in arch/sparc/net/bpf_jit_asm.S */
+extern u32 bpf_jit_load_word[];
+extern u32 bpf_jit_load_half[];
+extern u32 bpf_jit_load_byte[];
+extern u32 bpf_jit_load_byte_msh[];
+extern u32 bpf_jit_load_word_positive_offset[];
+extern u32 bpf_jit_load_half_positive_offset[];
+extern u32 bpf_jit_load_byte_positive_offset[];
+extern u32 bpf_jit_load_byte_msh_positive_offset[];
+extern u32 bpf_jit_load_word_negative_offset[];
+extern u32 bpf_jit_load_half_negative_offset[];
+extern u32 bpf_jit_load_byte_negative_offset[];
+extern u32 bpf_jit_load_byte_msh_negative_offset[];
+
#else
#define r_SKB %o0
#define r_A %o1
diff --git a/arch/sparc/net/bpf_jit_asm.S b/arch/sparc/net/bpf_jit_asm.S
index 46d8f59f14c5..9d016c7017f7 100644
--- a/arch/sparc/net/bpf_jit_asm.S
+++ b/arch/sparc/net/bpf_jit_asm.S
@@ -195,5 +195,11 @@ bpf_jit_load_byte_msh_negative_offset:
sll r_OFF, 2, r_X
bpf_error:
+ /* Make the JIT program return zero. The JIT epilogue
+ * stores away the original %o7 into r_saved_O7. The
+ * normal leaf function return is to use "retl" which
+ * would evalute to "jmpl %o7 + 8, %g0" but we want to
+ * use the saved value thus the sequence you see here.
+ */
jmpl r_saved_O7 + 8, %g0
clr %o0
diff --git a/arch/sparc/net/bpf_jit_comp.c b/arch/sparc/net/bpf_jit_comp.c
index ebc89809f585..4ce0296575eb 100644
--- a/arch/sparc/net/bpf_jit_comp.c
+++ b/arch/sparc/net/bpf_jit_comp.c
@@ -11,20 +11,6 @@
int bpf_jit_enable __read_mostly;
-/* assembly code in arch/sparc/net/bpf_jit_asm.S */
-extern u32 bpf_jit_load_word[];
-extern u32 bpf_jit_load_half[];
-extern u32 bpf_jit_load_byte[];
-extern u32 bpf_jit_load_byte_msh[];
-extern u32 bpf_jit_load_word_positive_offset[];
-extern u32 bpf_jit_load_half_positive_offset[];
-extern u32 bpf_jit_load_byte_positive_offset[];
-extern u32 bpf_jit_load_byte_msh_positive_offset[];
-extern u32 bpf_jit_load_word_negative_offset[];
-extern u32 bpf_jit_load_half_negative_offset[];
-extern u32 bpf_jit_load_byte_negative_offset[];
-extern u32 bpf_jit_load_byte_msh_negative_offset[];
-
static inline bool is_simm13(unsigned int value)
{
return value + 0x1000 < 0x2000;
@@ -65,22 +51,22 @@ static void bpf_flush_icache(void *start_, void *end_)
#define F2(X, Y) (OP(X) | OP2(Y))
#define F3(X, Y) (OP(X) | OP3(Y))
-#define CONDN COND (0x0)
-#define CONDE COND (0x1)
-#define CONDLE COND (0x2)
-#define CONDL COND (0x3)
-#define CONDLEU COND (0x4)
-#define CONDCS COND (0x5)
-#define CONDNEG COND (0x6)
-#define CONDVC COND (0x7)
-#define CONDA COND (0x8)
-#define CONDNE COND (0x9)
-#define CONDG COND (0xa)
-#define CONDGE COND (0xb)
-#define CONDGU COND (0xc)
-#define CONDCC COND (0xd)
-#define CONDPOS COND (0xe)
-#define CONDVS COND (0xf)
+#define CONDN COND(0x0)
+#define CONDE COND(0x1)
+#define CONDLE COND(0x2)
+#define CONDL COND(0x3)
+#define CONDLEU COND(0x4)
+#define CONDCS COND(0x5)
+#define CONDNEG COND(0x6)
+#define CONDVC COND(0x7)
+#define CONDA COND(0x8)
+#define CONDNE COND(0x9)
+#define CONDG COND(0xa)
+#define CONDGE COND(0xb)
+#define CONDGU COND(0xc)
+#define CONDCC COND(0xd)
+#define CONDPOS COND(0xe)
+#define CONDVS COND(0xf)
#define CONDGEU CONDCC
#define CONDLU CONDCS
@@ -172,7 +158,7 @@ do { /* sethi %hi(K), REG */ \
/* Emit
*
- * OP r_A, r_X, r_A
+ * OP r_A, r_X, r_A
*/
#define emit_alu_X(OPCODE) \
do { \
@@ -195,7 +181,7 @@ do { \
* is zero.
*/
#define emit_alu_K(OPCODE, K) \
-do { \
+do { \
if (K) { \
unsigned int _insn = OPCODE; \
_insn |= RS1(r_A) | RD(r_A); \
@@ -204,7 +190,7 @@ do { \
} else { \
emit_set_const(K, r_TMP); \
*prog++ = _insn | RS2(r_TMP); \
- } \
+ } \
} \
} while (0)
@@ -222,37 +208,37 @@ do { \
do { unsigned int _off = offsetof(STRUCT, FIELD); \
BUILD_BUG_ON(FIELD_SIZEOF(STRUCT, FIELD) != sizeof(void *)); \
*prog++ = LDPTRI | RS1(BASE) | S13(_off) | RD(DEST); \
-} while(0)
+} while (0)
#define emit_load32(BASE, STRUCT, FIELD, DEST) \
do { unsigned int _off = offsetof(STRUCT, FIELD); \
BUILD_BUG_ON(FIELD_SIZEOF(STRUCT, FIELD) != sizeof(u32)); \
*prog++ = LD32I | RS1(BASE) | S13(_off) | RD(DEST); \
-} while(0)
+} while (0)
#define emit_load16(BASE, STRUCT, FIELD, DEST) \
do { unsigned int _off = offsetof(STRUCT, FIELD); \
BUILD_BUG_ON(FIELD_SIZEOF(STRUCT, FIELD) != sizeof(u16)); \
*prog++ = LD16I | RS1(BASE) | S13(_off) | RD(DEST); \
-} while(0)
+} while (0)
#define __emit_load8(BASE, STRUCT, FIELD, DEST) \
do { unsigned int _off = offsetof(STRUCT, FIELD); \
*prog++ = LD8I | RS1(BASE) | S13(_off) | RD(DEST); \
-} while(0)
+} while (0)
#define emit_load8(BASE, STRUCT, FIELD, DEST) \
do { BUILD_BUG_ON(FIELD_SIZEOF(STRUCT, FIELD) != sizeof(u8)); \
__emit_load8(BASE, STRUCT, FIELD, DEST); \
-} while(0)
+} while (0)
#define emit_ldmem(OFF, DEST) \
do { *prog++ = LD32I | RS1(FP) | S13(-(OFF)) | RD(DEST); \
-} while(0)
+} while (0)
#define emit_stmem(OFF, SRC) \
do { *prog++ = LD32I | RS1(FP) | S13(-(OFF)) | RD(SRC); \
-} while(0)
+} while (0)
#define cpu_off offsetof(struct thread_info, cpu)
@@ -292,16 +278,16 @@ do { void *_here = image + addrs[i] - 8; \
#define emit_branch(BR_OPC, DEST) \
do { unsigned int _here = addrs[i] - 8; \
*prog++ = BR_OPC | WDISP22((DEST) - _here); \
-} while(0)
+} while (0)
#define emit_branch_off(BR_OPC, OFF) \
do { *prog++ = BR_OPC | WDISP22(OFF); \
-} while(0)
+} while (0)
#define emit_jump(DEST) emit_branch(BA, DEST)
-#define emit_read_y(REG) *prog++ = RD_Y | RD(REG);
-#define emit_write_y(REG) *prog++ = WR_Y | IMMED | RS1(REG) | S13(0);
+#define emit_read_y(REG) *prog++ = RD_Y | RD(REG)
+#define emit_write_y(REG) *prog++ = WR_Y | IMMED | RS1(REG) | S13(0)
#define emit_cmp(R1, R2) \
*prog++ = (SUBCC | RS1(R1) | RS2(R2) | RD(G0))
@@ -333,6 +319,35 @@ do { *prog++ = BR_OPC | WDISP22(OFF); \
#define emit_release_stack(SZ) \
*prog++ = (ADD | IMMED | RS1(SP) | S13(SZ) | RD(SP))
+/* A note about branch offset calculations. The addrs[] array,
+ * indexed by BPF instruction, records the address after all the
+ * sparc instructions emitted for that BPF instruction.
+ *
+ * The most common case is to emit a branch at the end of such
+ * a code sequence. So this would be two instructions, the
+ * branch and it's delay slot.
+ *
+ * Therefore by default the branch emitters calculate the branch
+ * offset field as:
+ *
+ * destination - (addrs[i] - 8)
+ *
+ * This "addrs[i] - 8" is the address of the branch itself or
+ * what "." would be in assembler notation. The "8" part is
+ * how we take into consideration the branch and it's delay
+ * slot mentioned above.
+ *
+ * Sometimes we need to emit a branch earlier in the code
+ * sequence. And in these situations we adjust "destination"
+ * to accomodate this difference. For example, if we needed
+ * to emit a branch (and it's delay slot) right before the
+ * final instruction emitted for a BPF opcode, we'd use
+ * "destination + 4" instead of just plain "destination" above.
+ *
+ * This is why you see all of these funny emit_branch() and
+ * emit_jump() calls with adjusted offsets.
+ */
+
void bpf_jit_compile(struct sk_filter *fp)
{
unsigned int cleanup_addr, proglen, oldproglen = 0;
@@ -493,6 +508,10 @@ void bpf_jit_compile(struct sk_filter *fp)
}
emit_write_y(G0);
#ifdef CONFIG_SPARC32
+ /* The Sparc v8 architecture requires
+ * three instructions between a %y
+ * register write and the first use.
+ */
emit_nop();
emit_nop();
emit_nop();