@@ -237,9 +237,55 @@ static inline void emit(u32 inst, struct jit_ctx *ctx)
}
/*
+ * This is rather horrid, but necessary to convert an integer constant
+ * to an immediate operand for the opcodes, and be able to detect at
+ * build time whether the constant can't be converted (iow, usable in
+ * BUILD_BUG_ON()).
+ */
+#define imm12val(v, s) (rol32(v, (s)) | (s) << 7)
+#define const_imm8m(x) \
+ ({ int r; \
+ u32 v = (x); \
+ if (!(v & ~0x000000ff)) \
+ r = imm12val(v, 0); \
+ else if (!(v & ~0xc000003f)) \
+ r = imm12val(v, 2); \
+ else if (!(v & ~0xf000000f)) \
+ r = imm12val(v, 4); \
+ else if (!(v & ~0xfc000003)) \
+ r = imm12val(v, 6); \
+ else if (!(v & ~0xff000000)) \
+ r = imm12val(v, 8); \
+ else if (!(v & ~0x3fc00000)) \
+ r = imm12val(v, 10); \
+ else if (!(v & ~0x0ff00000)) \
+ r = imm12val(v, 12); \
+ else if (!(v & ~0x03fc0000)) \
+ r = imm12val(v, 14); \
+ else if (!(v & ~0x00ff0000)) \
+ r = imm12val(v, 16); \
+ else if (!(v & ~0x003fc000)) \
+ r = imm12val(v, 18); \
+ else if (!(v & ~0x000ff000)) \
+ r = imm12val(v, 20); \
+ else if (!(v & ~0x0003fc00)) \
+ r = imm12val(v, 22); \
+ else if (!(v & ~0x0000ff00)) \
+ r = imm12val(v, 24); \
+ else if (!(v & ~0x00003fc0)) \
+ r = imm12val(v, 26); \
+ else if (!(v & ~0x00000ff0)) \
+ r = imm12val(v, 28); \
+ else if (!(v & ~0x000003fc)) \
+ r = imm12val(v, 30); \
+ else \
+ r = -1; \
+ r; })
+
+/*
* Checks if immediate value can be converted to imm12(12 bits) value.
*/
-static int16_t imm8m(u32 x)
+static int imm8m(u32 x)
{
u32 rot;
@@ -249,6 +295,8 @@ static int16_t imm8m(u32 x)
return -1;
}
+#define imm8m(x) (__builtin_constant_p(x) ? const_imm8m(x) : imm8m(x))
+
static u32 arm_bpf_ldst_imm12(u32 op, u8 rt, u8 rn, s16 imm12)
{
op |= rt << 12 | rn << 16;
Provide a version of the imm8m() function that the compiler can optimise when used with a constant expression. Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> --- arch/arm/net/bpf_jit_32.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 49 insertions(+), 1 deletion(-)