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Message-Id: <20241204-packing-pack-fields-and-ice-implementation-v9-3-81c8f2bd7323@intel.com>
Date: Wed, 04 Dec 2024 17:22:49 -0800
From: Jacob Keller <jacob.e.keller@...el.com>
To: Vladimir Oltean <vladimir.oltean@....com>,
Andrew Morton <akpm@...ux-foundation.org>,
Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, Tony Nguyen <anthony.l.nguyen@...el.com>,
Przemek Kitszel <przemyslaw.kitszel@...el.com>,
Masahiro Yamada <masahiroy@...nel.org>, netdev <netdev@...r.kernel.org>
Cc: Jacob Keller <jacob.e.keller@...el.com>
Subject: [PATCH net-next v9 03/10] lib: packing: add pack_fields() and
unpack_fields()
From: Vladimir Oltean <vladimir.oltean@....com>
This is new API which caters to the following requirements:
- Pack or unpack a large number of fields to/from a buffer with a small
code footprint. The current alternative is to open-code a large number
of calls to pack() and unpack(), or to use packing() to reduce that
number to half. But packing() is not const-correct.
- Use unpacked numbers stored in variables smaller than u64. This
reduces the rodata footprint of the stored field arrays.
- Perform error checking at compile time, rather than runtime, and return
void from the API functions. Because the C preprocessor can't generate
variable length code (loops), this is a bit tricky to do with macros.
To handle this, implement macros which sanity check the packed field
definitions based on their size. Finally, a single macro with a chain of
__builtin_choose_expr() is used to select the appropriate macros. We
enforce the use of ascending or descending order to avoid O(N^2) scaling
when checking for overlap. Note that the macros are written with care to
ensure that the compilers can correctly evaluate the resulting code at
compile time. In particular, care was taken with avoiding too many nested
statement expressions. Nested statement expressions trip up some
compilers, especially when passing down variables created in previous
statement expressions.
There are two key design choices intended to keep the overall macro code
size small. First, the definition of each CHECK_PACKED_FIELDS_N macro is
implemented recursively, by calling the N-1 macro. This avoids needing
the code to repeat multiple times.
Second, the CHECK_PACKED_FIELD macro enforces that the fields in the
array are sorted in order. This allows checking for overlap only with
neighboring fields, rather than the general overlap case where each field
would need to be checked against other fields.
The overlap checks use the first two fields to determine the order of the
remaining fields, thus allowing either ascending or descending order.
This enables drivers the flexibility to keep the fields ordered in which
ever order most naturally fits their hardware design and its associated
documentation.
The CHECK_PACKED_FIELDS macro is directly called from within pack_fields
and unpack_fields, ensuring that all drivers using the API receive the
benefits of the compile-time checks. Users do not need to directly call
any of the macros directly.
The CHECK_PACKED_FIELDS and its helper macros CHECK_PACKED_FIELDS_(0..50)
are generated using a simple C program in scripts/gen_packed_field_checks.c
This program can be compiled on demand and executed to generate the macro
code in include/linux/packing.h. This will aid in the event that a driver
needs more than 50 fields. The generator can be updated with a new size,
and used to update the packing.h header file. In practice, the ice driver
will need to support 27 fields, and the sja1105 driver will need to
support 40 fields. This on-demand generation avoids the need to modify
Kbuild. We do not anticipate the maximum number of fields to grow very
often.
- Reduced rodata footprint for the storage of the packed field arrays.
To that end, we have struct packed_field_s (small) and packed_field_m
(medium). More can be added as needed (unlikely for now). On these
types, the same generic pack_fields() and unpack_fields() API can be
used, thanks to the new C11 _Generic() selection feature, which can
call pack_fields_s() or pack_fields_m(), depending on the type of the
"fields" array - a simplistic form of polymorphism. It is evaluated at
compile time which function will actually be called.
Over time, packing() is expected to be completely replaced either with
pack() or with pack_fields().
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
Co-developed-by: Jacob Keller <jacob.e.keller@...el.com>
Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
---
Makefile | 4 +
include/linux/packing.h | 427 ++++++++++++++++++++++++++++++++++++++
lib/packing.c | 145 +++++++++++++
lib/packing_test.c | 61 ++++++
scripts/gen_packed_field_checks.c | 37 ++++
MAINTAINERS | 1 +
scripts/Makefile | 2 +-
7 files changed, 676 insertions(+), 1 deletion(-)
diff --git a/Makefile b/Makefile
index 8129de0b214f5b73a3b1cca0798041d74270836b..58496942a7d13c6a53e4210d83deb2cc2033d00a 100644
--- a/Makefile
+++ b/Makefile
@@ -1315,6 +1315,10 @@ PHONY += scripts_unifdef
scripts_unifdef: scripts_basic
$(Q)$(MAKE) $(build)=scripts scripts/unifdef
+PHONY += scripts_gen_packed_field_checks
+scripts_gen_packed_field_checks: scripts_basic
+ $(Q)$(MAKE) $(build)=scripts scripts/gen_packed_field_checks
+
# ---------------------------------------------------------------------------
# Install
diff --git a/include/linux/packing.h b/include/linux/packing.h
index 5d36dcd06f60420325473dae3a0e9ac37d03da4b..d9454ea7fdcdec142796f5bbec1fccb7e74d5fbb 100644
--- a/include/linux/packing.h
+++ b/include/linux/packing.h
@@ -8,6 +8,85 @@
#include <linux/types.h>
#include <linux/bitops.h>
+#define GEN_PACKED_FIELD_MEMBERS(__type) \
+ __type startbit; \
+ __type endbit; \
+ __type offset; \
+ __type size
+
+/* Small packed field. Use with bit offsets < 256, buffers < 32B and
+ * unpacked structures < 256B.
+ */
+struct packed_field_s {
+ GEN_PACKED_FIELD_MEMBERS(u8);
+};
+
+/* Medium packed field. Use with bit offsets < 65536, buffers < 8KB and
+ * unpacked structures < 64KB.
+ */
+struct packed_field_m {
+ GEN_PACKED_FIELD_MEMBERS(u16);
+};
+
+#define PACKED_FIELD(start, end, struct_name, struct_field) \
+{ \
+ (start), \
+ (end), \
+ offsetof(struct_name, struct_field), \
+ sizeof_field(struct_name, struct_field), \
+}
+
+#define CHECK_PACKED_FIELD_OVERLAP(fields, index1, index2) ({ \
+ typeof(&(fields)[0]) __f = (fields); \
+ typeof(__f[0]) _f1 = __f[index1]; typeof(__f[0]) _f2 = __f[index2]; \
+ const bool _ascending = __f[0].startbit < __f[1].startbit; \
+ BUILD_BUG_ON_MSG(_ascending && _f1.startbit >= _f2.startbit, \
+ __stringify(fields) " field " __stringify(index2) \
+ " breaks ascending order"); \
+ BUILD_BUG_ON_MSG(!_ascending && _f1.startbit <= _f2.startbit, \
+ __stringify(fields) " field " __stringify(index2) \
+ " breaks descending order"); \
+ BUILD_BUG_ON_MSG(max(_f1.endbit, _f2.endbit) <= \
+ min(_f1.startbit, _f2.startbit), \
+ __stringify(fields) " field " __stringify(index2) \
+ " overlaps with previous field"); \
+})
+
+#define CHECK_PACKED_FIELD(fields, index) ({ \
+ typeof(&(fields)[0]) _f = (fields); \
+ typeof(_f[0]) __f = _f[index]; \
+ BUILD_BUG_ON_MSG(__f.startbit < __f.endbit, \
+ __stringify(fields) " field " __stringify(index) \
+ " start bit must not be smaller than end bit"); \
+ BUILD_BUG_ON_MSG(__f.size != 1 && __f.size != 2 && \
+ __f.size != 4 && __f.size != 8, \
+ __stringify(fields) " field " __stringify(index) \
+ " has unsupported unpacked storage size"); \
+ BUILD_BUG_ON_MSG(__f.startbit - __f.endbit >= BITS_PER_BYTE * __f.size, \
+ __stringify(fields) " field " __stringify(index) \
+ " exceeds unpacked storage size"); \
+ __builtin_choose_expr(index != 0, \
+ CHECK_PACKED_FIELD_OVERLAP(fields, index - 1, index), \
+ 1); \
+})
+
+/* Note that the packed fields may be either in ascending or descending order.
+ * Thus, we must check that both the first and last field wit within the
+ * packed buffer size.
+ */
+#define CHECK_PACKED_FIELDS_SIZE(fields, pbuflen) ({ \
+ typeof(&(fields)[0]) _f = (fields); \
+ typeof(pbuflen) _len = (pbuflen); \
+ const size_t num_fields = ARRAY_SIZE(fields); \
+ BUILD_BUG_ON_MSG(!__builtin_constant_p(_len), \
+ __stringify(fields) " pbuflen " __stringify(pbuflen) \
+ " must be a compile time constant"); \
+ BUILD_BUG_ON_MSG(_f[0].startbit >= BITS_PER_BYTE * _len, \
+ __stringify(fields) " first field exceeds packed buffer size"); \
+ BUILD_BUG_ON_MSG(_f[num_fields - 1].startbit >= BITS_PER_BYTE * _len, \
+ __stringify(fields) " last field exceeds packed buffer size"); \
+})
+
#define QUIRK_MSB_ON_THE_RIGHT BIT(0)
#define QUIRK_LITTLE_ENDIAN BIT(1)
#define QUIRK_LSW32_IS_FIRST BIT(2)
@@ -26,4 +105,352 @@ int pack(void *pbuf, u64 uval, size_t startbit, size_t endbit, size_t pbuflen,
int unpack(const void *pbuf, u64 *uval, size_t startbit, size_t endbit,
size_t pbuflen, u8 quirks);
+void pack_fields_s(void *pbuf, size_t pbuflen, const void *ustruct,
+ const struct packed_field_s *fields, size_t num_fields,
+ u8 quirks);
+
+void pack_fields_m(void *pbuf, size_t pbuflen, const void *ustruct,
+ const struct packed_field_m *fields, size_t num_fields,
+ u8 quirks);
+
+void unpack_fields_s(const void *pbuf, size_t pbuflen, void *ustruct,
+ const struct packed_field_s *fields, size_t num_fields,
+ u8 quirks);
+
+void unpack_fields_m(const void *pbuf, size_t pbuflen, void *ustruct,
+ const struct packed_field_m *fields, size_t num_fields,
+ u8 quirks);
+
+/* Do not hand-edit the following packed field check macros!
+ *
+ * They are generated using scripts/gen_packed_field_checks.c, which may be
+ * built via "make scripts_gen_packed_field_checks". If larger macro sizes are
+ * needed in the future, please use this program to re-generate the macros and
+ * insert them here.
+ */
+
+#define CHECK_PACKED_FIELDS_1(fields) \
+ CHECK_PACKED_FIELD(fields, 0)
+
+#define CHECK_PACKED_FIELDS_2(fields) do { \
+ CHECK_PACKED_FIELDS_1(fields); \
+ CHECK_PACKED_FIELD(fields, 1); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_3(fields) do { \
+ CHECK_PACKED_FIELDS_2(fields); \
+ CHECK_PACKED_FIELD(fields, 2); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_4(fields) do { \
+ CHECK_PACKED_FIELDS_3(fields); \
+ CHECK_PACKED_FIELD(fields, 3); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_5(fields) do { \
+ CHECK_PACKED_FIELDS_4(fields); \
+ CHECK_PACKED_FIELD(fields, 4); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_6(fields) do { \
+ CHECK_PACKED_FIELDS_5(fields); \
+ CHECK_PACKED_FIELD(fields, 5); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_7(fields) do { \
+ CHECK_PACKED_FIELDS_6(fields); \
+ CHECK_PACKED_FIELD(fields, 6); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_8(fields) do { \
+ CHECK_PACKED_FIELDS_7(fields); \
+ CHECK_PACKED_FIELD(fields, 7); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_9(fields) do { \
+ CHECK_PACKED_FIELDS_8(fields); \
+ CHECK_PACKED_FIELD(fields, 8); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_10(fields) do { \
+ CHECK_PACKED_FIELDS_9(fields); \
+ CHECK_PACKED_FIELD(fields, 9); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_11(fields) do { \
+ CHECK_PACKED_FIELDS_10(fields); \
+ CHECK_PACKED_FIELD(fields, 10); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_12(fields) do { \
+ CHECK_PACKED_FIELDS_11(fields); \
+ CHECK_PACKED_FIELD(fields, 11); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_13(fields) do { \
+ CHECK_PACKED_FIELDS_12(fields); \
+ CHECK_PACKED_FIELD(fields, 12); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_14(fields) do { \
+ CHECK_PACKED_FIELDS_13(fields); \
+ CHECK_PACKED_FIELD(fields, 13); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_15(fields) do { \
+ CHECK_PACKED_FIELDS_14(fields); \
+ CHECK_PACKED_FIELD(fields, 14); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_16(fields) do { \
+ CHECK_PACKED_FIELDS_15(fields); \
+ CHECK_PACKED_FIELD(fields, 15); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_17(fields) do { \
+ CHECK_PACKED_FIELDS_16(fields); \
+ CHECK_PACKED_FIELD(fields, 16); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_18(fields) do { \
+ CHECK_PACKED_FIELDS_17(fields); \
+ CHECK_PACKED_FIELD(fields, 17); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_19(fields) do { \
+ CHECK_PACKED_FIELDS_18(fields); \
+ CHECK_PACKED_FIELD(fields, 18); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_20(fields) do { \
+ CHECK_PACKED_FIELDS_19(fields); \
+ CHECK_PACKED_FIELD(fields, 19); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_21(fields) do { \
+ CHECK_PACKED_FIELDS_20(fields); \
+ CHECK_PACKED_FIELD(fields, 20); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_22(fields) do { \
+ CHECK_PACKED_FIELDS_21(fields); \
+ CHECK_PACKED_FIELD(fields, 21); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_23(fields) do { \
+ CHECK_PACKED_FIELDS_22(fields); \
+ CHECK_PACKED_FIELD(fields, 22); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_24(fields) do { \
+ CHECK_PACKED_FIELDS_23(fields); \
+ CHECK_PACKED_FIELD(fields, 23); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_25(fields) do { \
+ CHECK_PACKED_FIELDS_24(fields); \
+ CHECK_PACKED_FIELD(fields, 24); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_26(fields) do { \
+ CHECK_PACKED_FIELDS_25(fields); \
+ CHECK_PACKED_FIELD(fields, 25); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_27(fields) do { \
+ CHECK_PACKED_FIELDS_26(fields); \
+ CHECK_PACKED_FIELD(fields, 26); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_28(fields) do { \
+ CHECK_PACKED_FIELDS_27(fields); \
+ CHECK_PACKED_FIELD(fields, 27); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_29(fields) do { \
+ CHECK_PACKED_FIELDS_28(fields); \
+ CHECK_PACKED_FIELD(fields, 28); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_30(fields) do { \
+ CHECK_PACKED_FIELDS_29(fields); \
+ CHECK_PACKED_FIELD(fields, 29); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_31(fields) do { \
+ CHECK_PACKED_FIELDS_30(fields); \
+ CHECK_PACKED_FIELD(fields, 30); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_32(fields) do { \
+ CHECK_PACKED_FIELDS_31(fields); \
+ CHECK_PACKED_FIELD(fields, 31); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_33(fields) do { \
+ CHECK_PACKED_FIELDS_32(fields); \
+ CHECK_PACKED_FIELD(fields, 32); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_34(fields) do { \
+ CHECK_PACKED_FIELDS_33(fields); \
+ CHECK_PACKED_FIELD(fields, 33); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_35(fields) do { \
+ CHECK_PACKED_FIELDS_34(fields); \
+ CHECK_PACKED_FIELD(fields, 34); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_36(fields) do { \
+ CHECK_PACKED_FIELDS_35(fields); \
+ CHECK_PACKED_FIELD(fields, 35); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_37(fields) do { \
+ CHECK_PACKED_FIELDS_36(fields); \
+ CHECK_PACKED_FIELD(fields, 36); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_38(fields) do { \
+ CHECK_PACKED_FIELDS_37(fields); \
+ CHECK_PACKED_FIELD(fields, 37); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_39(fields) do { \
+ CHECK_PACKED_FIELDS_38(fields); \
+ CHECK_PACKED_FIELD(fields, 38); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_40(fields) do { \
+ CHECK_PACKED_FIELDS_39(fields); \
+ CHECK_PACKED_FIELD(fields, 39); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_41(fields) do { \
+ CHECK_PACKED_FIELDS_40(fields); \
+ CHECK_PACKED_FIELD(fields, 40); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_42(fields) do { \
+ CHECK_PACKED_FIELDS_41(fields); \
+ CHECK_PACKED_FIELD(fields, 41); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_43(fields) do { \
+ CHECK_PACKED_FIELDS_42(fields); \
+ CHECK_PACKED_FIELD(fields, 42); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_44(fields) do { \
+ CHECK_PACKED_FIELDS_43(fields); \
+ CHECK_PACKED_FIELD(fields, 43); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_45(fields) do { \
+ CHECK_PACKED_FIELDS_44(fields); \
+ CHECK_PACKED_FIELD(fields, 44); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_46(fields) do { \
+ CHECK_PACKED_FIELDS_45(fields); \
+ CHECK_PACKED_FIELD(fields, 45); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_47(fields) do { \
+ CHECK_PACKED_FIELDS_46(fields); \
+ CHECK_PACKED_FIELD(fields, 46); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_48(fields) do { \
+ CHECK_PACKED_FIELDS_47(fields); \
+ CHECK_PACKED_FIELD(fields, 47); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_49(fields) do { \
+ CHECK_PACKED_FIELDS_48(fields); \
+ CHECK_PACKED_FIELD(fields, 48); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS_50(fields) do { \
+ CHECK_PACKED_FIELDS_49(fields); \
+ CHECK_PACKED_FIELD(fields, 49); \
+} while (0)
+
+#define CHECK_PACKED_FIELDS(fields) \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 1, ({ CHECK_PACKED_FIELDS_1(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 2, ({ CHECK_PACKED_FIELDS_2(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 3, ({ CHECK_PACKED_FIELDS_3(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 4, ({ CHECK_PACKED_FIELDS_4(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 5, ({ CHECK_PACKED_FIELDS_5(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 6, ({ CHECK_PACKED_FIELDS_6(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 7, ({ CHECK_PACKED_FIELDS_7(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 8, ({ CHECK_PACKED_FIELDS_8(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 9, ({ CHECK_PACKED_FIELDS_9(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 10, ({ CHECK_PACKED_FIELDS_10(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 11, ({ CHECK_PACKED_FIELDS_11(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 12, ({ CHECK_PACKED_FIELDS_12(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 13, ({ CHECK_PACKED_FIELDS_13(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 14, ({ CHECK_PACKED_FIELDS_14(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 15, ({ CHECK_PACKED_FIELDS_15(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 16, ({ CHECK_PACKED_FIELDS_16(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 17, ({ CHECK_PACKED_FIELDS_17(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 18, ({ CHECK_PACKED_FIELDS_18(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 19, ({ CHECK_PACKED_FIELDS_19(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 20, ({ CHECK_PACKED_FIELDS_20(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 21, ({ CHECK_PACKED_FIELDS_21(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 22, ({ CHECK_PACKED_FIELDS_22(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 23, ({ CHECK_PACKED_FIELDS_23(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 24, ({ CHECK_PACKED_FIELDS_24(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 25, ({ CHECK_PACKED_FIELDS_25(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 26, ({ CHECK_PACKED_FIELDS_26(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 27, ({ CHECK_PACKED_FIELDS_27(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 28, ({ CHECK_PACKED_FIELDS_28(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 29, ({ CHECK_PACKED_FIELDS_29(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 30, ({ CHECK_PACKED_FIELDS_30(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 31, ({ CHECK_PACKED_FIELDS_31(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 32, ({ CHECK_PACKED_FIELDS_32(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 33, ({ CHECK_PACKED_FIELDS_33(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 34, ({ CHECK_PACKED_FIELDS_34(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 35, ({ CHECK_PACKED_FIELDS_35(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 36, ({ CHECK_PACKED_FIELDS_36(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 37, ({ CHECK_PACKED_FIELDS_37(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 38, ({ CHECK_PACKED_FIELDS_38(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 39, ({ CHECK_PACKED_FIELDS_39(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 40, ({ CHECK_PACKED_FIELDS_40(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 41, ({ CHECK_PACKED_FIELDS_41(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 42, ({ CHECK_PACKED_FIELDS_42(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 43, ({ CHECK_PACKED_FIELDS_43(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 44, ({ CHECK_PACKED_FIELDS_44(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 45, ({ CHECK_PACKED_FIELDS_45(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 46, ({ CHECK_PACKED_FIELDS_46(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 47, ({ CHECK_PACKED_FIELDS_47(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 48, ({ CHECK_PACKED_FIELDS_48(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 49, ({ CHECK_PACKED_FIELDS_49(fields); }), \
+ __builtin_choose_expr(ARRAY_SIZE(fields) == 50, ({ CHECK_PACKED_FIELDS_50(fields); }), \
+ ({ BUILD_BUG_ON_MSG(1, "CHECK_PACKED_FIELDS() must be regenerated to support array sizes larger than 50."); }) \
+))))))))))))))))))))))))))))))))))))))))))))))))))
+
+/* End of generated content */
+
+#define pack_fields(pbuf, pbuflen, ustruct, fields, quirks) \
+ ({ \
+ CHECK_PACKED_FIELDS(fields); \
+ CHECK_PACKED_FIELDS_SIZE((fields), (pbuflen)); \
+ _Generic((fields), \
+ const struct packed_field_s * : pack_fields_s, \
+ const struct packed_field_m * : pack_fields_m \
+ )((pbuf), (pbuflen), (ustruct), (fields), ARRAY_SIZE(fields), (quirks)); \
+ })
+
+#define unpack_fields(pbuf, pbuflen, ustruct, fields, quirks) \
+ ({ \
+ CHECK_PACKED_FIELDS(fields); \
+ CHECK_PACKED_FIELDS_SIZE((fields), (pbuflen)); \
+ _Generic((fields), \
+ const struct packed_field_s * : unpack_fields_s, \
+ const struct packed_field_m * : unpack_fields_m \
+ )((pbuf), (pbuflen), (ustruct), (fields), ARRAY_SIZE(fields), (quirks)); \
+ })
+
#endif
diff --git a/lib/packing.c b/lib/packing.c
index 09a2d195b9433b61c86f3b63ff019ab319c83e97..45164f73fe5bf9f2c547eb22016af7e44fed9eb0 100644
--- a/lib/packing.c
+++ b/lib/packing.c
@@ -5,10 +5,37 @@
#include <linux/packing.h>
#include <linux/module.h>
#include <linux/bitops.h>
+#include <linux/bits.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/bitrev.h>
+#define __pack_fields(pbuf, pbuflen, ustruct, fields, num_fields, quirks) \
+ ({ \
+ for (size_t i = 0; i < (num_fields); i++) { \
+ typeof(&(fields)[0]) field = &(fields)[i]; \
+ u64 uval; \
+ \
+ uval = ustruct_field_to_u64(ustruct, field->offset, field->size); \
+ \
+ __pack(pbuf, uval, field->startbit, field->endbit, \
+ pbuflen, quirks); \
+ } \
+ })
+
+#define __unpack_fields(pbuf, pbuflen, ustruct, fields, num_fields, quirks) \
+ ({ \
+ for (size_t i = 0; i < (num_fields); i++) { \
+ typeof(&(fields)[0]) field = &fields[i]; \
+ u64 uval; \
+ \
+ __unpack(pbuf, &uval, field->startbit, field->endbit, \
+ pbuflen, quirks); \
+ \
+ u64_to_ustruct_field(ustruct, field->offset, field->size, uval); \
+ } \
+ })
+
/**
* calculate_box_addr - Determine physical location of byte in buffer
* @box: Index of byte within buffer seen as a logical big-endian big number
@@ -322,4 +349,122 @@ int packing(void *pbuf, u64 *uval, int startbit, int endbit, size_t pbuflen,
}
EXPORT_SYMBOL(packing);
+static u64 ustruct_field_to_u64(const void *ustruct, size_t field_offset,
+ size_t field_size)
+{
+ switch (field_size) {
+ case 1:
+ return *((u8 *)(ustruct + field_offset));
+ case 2:
+ return *((u16 *)(ustruct + field_offset));
+ case 4:
+ return *((u32 *)(ustruct + field_offset));
+ default:
+ return *((u64 *)(ustruct + field_offset));
+ }
+}
+
+static void u64_to_ustruct_field(void *ustruct, size_t field_offset,
+ size_t field_size, u64 uval)
+{
+ switch (field_size) {
+ case 1:
+ *((u8 *)(ustruct + field_offset)) = uval;
+ break;
+ case 2:
+ *((u16 *)(ustruct + field_offset)) = uval;
+ break;
+ case 4:
+ *((u32 *)(ustruct + field_offset)) = uval;
+ break;
+ default:
+ *((u64 *)(ustruct + field_offset)) = uval;
+ break;
+ }
+}
+
+/**
+ * pack_fields_s - Pack array of small fields
+ *
+ * @pbuf: Pointer to a buffer holding the packed value.
+ * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf.
+ * @ustruct: Pointer to CPU-readable structure holding the unpacked value.
+ * It is expected (but not checked) that this has the same data type
+ * as all struct packed_field_s definitions.
+ * @fields: Array of small packed fields definition. They must not overlap.
+ * @num_fields: Length of @fields array.
+ * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and
+ * QUIRK_MSB_ON_THE_RIGHT.
+ */
+void pack_fields_s(void *pbuf, size_t pbuflen, const void *ustruct,
+ const struct packed_field_s *fields, size_t num_fields,
+ u8 quirks)
+{
+ __pack_fields(pbuf, pbuflen, ustruct, fields, num_fields, quirks);
+}
+EXPORT_SYMBOL(pack_fields_s);
+
+/**
+ * pack_fields_m - Pack array of medium fields
+ *
+ * @pbuf: Pointer to a buffer holding the packed value.
+ * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf.
+ * @ustruct: Pointer to CPU-readable structure holding the unpacked value.
+ * It is expected (but not checked) that this has the same data type
+ * as all struct packed_field_s definitions.
+ * @fields: Array of medium packed fields definition. They must not overlap.
+ * @num_fields: Length of @fields array.
+ * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and
+ * QUIRK_MSB_ON_THE_RIGHT.
+ */
+void pack_fields_m(void *pbuf, size_t pbuflen, const void *ustruct,
+ const struct packed_field_m *fields, size_t num_fields,
+ u8 quirks)
+{
+ __pack_fields(pbuf, pbuflen, ustruct, fields, num_fields, quirks);
+}
+EXPORT_SYMBOL(pack_fields_m);
+
+/**
+ * unpack_fields_s - Unpack array of small fields
+ *
+ * @pbuf: Pointer to a buffer holding the packed value.
+ * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf.
+ * @ustruct: Pointer to CPU-readable structure holding the unpacked value.
+ * It is expected (but not checked) that this has the same data type
+ * as all struct packed_field_s definitions.
+ * @fields: Array of small packed fields definition. They must not overlap.
+ * @num_fields: Length of @fields array.
+ * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and
+ * QUIRK_MSB_ON_THE_RIGHT.
+ */
+void unpack_fields_s(const void *pbuf, size_t pbuflen, void *ustruct,
+ const struct packed_field_s *fields, size_t num_fields,
+ u8 quirks)
+{
+ __unpack_fields(pbuf, pbuflen, ustruct, fields, num_fields, quirks);
+}
+EXPORT_SYMBOL(unpack_fields_s);
+
+/**
+ * unpack_fields_m - Unpack array of medium fields
+ *
+ * @pbuf: Pointer to a buffer holding the packed value.
+ * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf.
+ * @ustruct: Pointer to CPU-readable structure holding the unpacked value.
+ * It is expected (but not checked) that this has the same data type
+ * as all struct packed_field_s definitions.
+ * @fields: Array of medium packed fields definition. They must not overlap.
+ * @num_fields: Length of @fields array.
+ * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and
+ * QUIRK_MSB_ON_THE_RIGHT.
+ */
+void unpack_fields_m(const void *pbuf, size_t pbuflen, void *ustruct,
+ const struct packed_field_m *fields, size_t num_fields,
+ u8 quirks)
+{
+ __unpack_fields(pbuf, pbuflen, ustruct, fields, num_fields, quirks);
+}
+EXPORT_SYMBOL(unpack_fields_m);
+
MODULE_DESCRIPTION("Generic bitfield packing and unpacking");
diff --git a/lib/packing_test.c b/lib/packing_test.c
index b38ea43c03fd83639f18a6f3e2a42eae36118c45..3b4167ce56bf65fa4d66cb55d3215aecc33f64c4 100644
--- a/lib/packing_test.c
+++ b/lib/packing_test.c
@@ -396,9 +396,70 @@ static void packing_test_unpack(struct kunit *test)
KUNIT_EXPECT_EQ(test, uval, params->uval);
}
+#define PACKED_BUF_SIZE 8
+
+typedef struct __packed { u8 buf[PACKED_BUF_SIZE]; } packed_buf_t;
+
+struct test_data {
+ u32 field3;
+ u16 field2;
+ u16 field4;
+ u16 field6;
+ u8 field1;
+ u8 field5;
+};
+
+static const struct packed_field_s test_fields[] = {
+ PACKED_FIELD(63, 61, struct test_data, field1),
+ PACKED_FIELD(60, 52, struct test_data, field2),
+ PACKED_FIELD(51, 28, struct test_data, field3),
+ PACKED_FIELD(27, 14, struct test_data, field4),
+ PACKED_FIELD(13, 9, struct test_data, field5),
+ PACKED_FIELD(8, 0, struct test_data, field6),
+};
+
+static void packing_test_pack_fields(struct kunit *test)
+{
+ const struct test_data data = {
+ .field1 = 0x2,
+ .field2 = 0x100,
+ .field3 = 0xF00050,
+ .field4 = 0x7D3,
+ .field5 = 0x9,
+ .field6 = 0x10B,
+ };
+ packed_buf_t expect = {
+ .buf = { 0x50, 0x0F, 0x00, 0x05, 0x01, 0xF4, 0xD3, 0x0B },
+ };
+ packed_buf_t buf = {};
+
+ pack_fields(&buf, sizeof(buf), &data, test_fields, 0);
+
+ KUNIT_EXPECT_MEMEQ(test, &expect, &buf, sizeof(buf));
+}
+
+static void packing_test_unpack_fields(struct kunit *test)
+{
+ const packed_buf_t buf = {
+ .buf = { 0x17, 0x28, 0x10, 0x19, 0x3D, 0xA9, 0x07, 0x9C },
+ };
+ struct test_data data = {};
+
+ unpack_fields(&buf, sizeof(buf), &data, test_fields, 0);
+
+ KUNIT_EXPECT_EQ(test, 0, data.field1);
+ KUNIT_EXPECT_EQ(test, 0x172, data.field2);
+ KUNIT_EXPECT_EQ(test, 0x810193, data.field3);
+ KUNIT_EXPECT_EQ(test, 0x36A4, data.field4);
+ KUNIT_EXPECT_EQ(test, 0x3, data.field5);
+ KUNIT_EXPECT_EQ(test, 0x19C, data.field6);
+}
+
static struct kunit_case packing_test_cases[] = {
KUNIT_CASE_PARAM(packing_test_pack, packing_gen_params),
KUNIT_CASE_PARAM(packing_test_unpack, packing_gen_params),
+ KUNIT_CASE(packing_test_pack_fields),
+ KUNIT_CASE(packing_test_unpack_fields),
{},
};
diff --git a/scripts/gen_packed_field_checks.c b/scripts/gen_packed_field_checks.c
new file mode 100644
index 0000000000000000000000000000000000000000..4e0b6e1bf4be23d9d2cc8c0cb1f13fdcb6fd07a3
--- /dev/null
+++ b/scripts/gen_packed_field_checks.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2024, Intel Corporation
+#include <stdbool.h>
+#include <stdio.h>
+
+#define MAX_PACKED_FIELD_SIZE 50
+
+int main(int argc, char **argv)
+{
+ /* The first macro doesn't need a do/while loop */
+ printf("#define CHECK_PACKED_FIELDS_1(fields) \\\n");
+ printf("\tCHECK_PACKED_FIELD(fields, 0)\n\n");
+
+ /* Remaining macros require a do/while loop, and are implemented
+ * recursively by calling the previous iteration's macro.
+ */
+ for (int i = 2; i <= MAX_PACKED_FIELD_SIZE; i++) {
+ printf("#define CHECK_PACKED_FIELDS_%d(fields) do { \\\n", i);
+ printf("\tCHECK_PACKED_FIELDS_%d(fields); \\\n", i - 1);
+ printf("\tCHECK_PACKED_FIELD(fields, %d); \\\n", i - 1);
+ printf("} while (0)\n\n");
+ }
+
+ printf("#define CHECK_PACKED_FIELDS(fields) \\\n");
+
+ for (int i = 1; i <= MAX_PACKED_FIELD_SIZE; i++)
+ printf("\t__builtin_choose_expr(ARRAY_SIZE(fields) == %d, ({ CHECK_PACKED_FIELDS_%d(fields); }), \\\n",
+ i, i);
+
+ printf("\t({ BUILD_BUG_ON_MSG(1, \"CHECK_PACKED_FIELDS() must be regenerated to support array sizes larger than %d.\"); }) \\\n",
+ MAX_PACKED_FIELD_SIZE);
+
+ for (int i = 1; i <= MAX_PACKED_FIELD_SIZE; i++)
+ printf(")");
+
+ printf("\n");
+}
diff --git a/MAINTAINERS b/MAINTAINERS
index 0456a33ef65792bacb5d305a6384d245844fb743..397dfdab2d92a969d367dcf77207d387cda451e3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17561,6 +17561,7 @@ F: Documentation/core-api/packing.rst
F: include/linux/packing.h
F: lib/packing.c
F: lib/packing_test.c
+F: scripts/gen_packed_field_checks.c
PADATA PARALLEL EXECUTION MECHANISM
M: Steffen Klassert <steffen.klassert@...unet.com>
diff --git a/scripts/Makefile b/scripts/Makefile
index 6bcda4b9d054021b185488841cd36c6e0fb86d0c..546e8175e1c4c8209e67a7f92f7d1e795a030988 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -47,7 +47,7 @@ HOSTCFLAGS_sorttable.o += -DMCOUNT_SORT_ENABLED
endif
# The following programs are only built on demand
-hostprogs += unifdef
+hostprogs += unifdef gen_packed_field_checks
# The module linker script is preprocessed on demand
targets += module.lds
--
2.47.0.265.g4ca455297942
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