gcc13 warning: FFDC pointer alignment

[shenki]

In file included from libekb.C:19:
libekb.C: In function 'void libekb_get_sbe_ffdc(FFDC&, const sbeFfdcPacketType&, int)':
./hwpf/fapi2/include/error_info/set_sbe_error.H:1493:86: warning: converting a packed 'fapi2::sbeFfdc_t' pointer (alignment 1) to a 'const uint32_t' {aka 'const unsigned int'} pointer (alignment 4) may result in an unaligned pointer value [-Waddress-of-packed-member]
 1493 |    fapi2::variable_buffer l_buffer((uint32_t*)FFDC_BUFFER, size_bytes/4, size_bytes*8);\
      |                                                                                      ^
libekb.C:258:9: note: in expansion of macro 'FAPI_SET_SBE_ERROR'
  258 |         FAPI_SET_SBE_ERROR(rc, ffdc_pkt.fapiRc, ffdc_endian.data(), proc_index);
      |         ^~~~~~~~~~~~~~~~~~
In file included from ./hwpf/fapi2/include/plat/plat_utils.H:27,
                 from libekb.C:11:
./ekb/hwpf/fapi2/include/error_info_defs.H:53:8: note: defined here
   53 | struct sbeFfdc_t
      |        ^~~~~~~~~

[shenki]

This code is generated by the perl script here:

pub-ekb/hwpf/fapi2/tools/parseErrorInfo_p10.pl

Line 1893 in 7fd7e4d

print SBFILE " fapi2::variable_buffer l_buffer((uint32_t*)FFDC_BUFFER, size_bytes/4, size_bytes*8);\\\n";

The call site is here:

https://github.com/open-power/libekb_p10/blob/3d1b2963082d7725c3a4a2960d6f3f3336f401a7/libekb.C#L258

void libekb_get_sbe_ffdc(FFDC& ffdc, const sbeFfdcPacketType& ffdc_pkt,
                         int proc_index)
{
        using namespace fapi2;
        fapi2::ReturnCode rc;
        
        std::vector<sbeFfdc_t> ffdc_endian;

	FAPI_SET_SBE_ERROR(rc, ffdc_pkt.fapiRc, ffdc_endian.data(), proc_index);

typedef struct sbeFfdcPacket {
        uint32_t fapiRc;            // Fapi Rc
        uint32_t ffdcLengthInWords; // length of Fapi FFDC data
        uint32_t *ffdcData;         // fapi FFDC data
        ~sbeFfdcPacket()
        {
                // freeup the ffdcData allocated memory
                if (ffdcData) {
                        delete ffdcData;
                }
        }
} sbeFfdcPacketType;

struct sbeFfdc_t
{
    uint32_t  size;
    uint64_t  data;
} __attribute__((packed));

#define FAPI_SET_SBE_ERROR(RC,ERRVAL,FFDC_BUFFER,SBE_INSTANCE)\

FFDC_BUFFER is a ffdc_endian.data().

We are trying to take the data from the vector of struct sbeFfdc_t __attribute__(packed) and refer to it with a uint32_t *. Inside the variable_buffer constructor it inserts the data to bits_container iv_data.

typedef uint32_t container_unit;
typedef std::vector<container_unit> bits_container;

[shenki]

If I change the temporary buffer in libekb.C to a std::vector<uint32_t>:

--- a/libekb.C
+++ b/libekb.C
@@ -229,9 +229,9 @@ void libekb_get_sbe_ffdc(FFDC& ffdc, const sbeFfdcPacketType& ffdc_pkt,
        // Get size of FFDC data in bytes. exculde RC size.
        size_t size = (ffdc_pkt.ffdcLengthInWords - 1) * sizeof(uint32_t);
 
-       // Create temporary sbeFfdc_t to store the data after endianess
-       // conversion.
-       std::vector<sbeFfdc_t> ffdc_endian;
+       // Create temporary vector to store the data after endianess
+       // conversion. 
+       std::vector<uint32_t> ffdc_endian;
 
        // get size of sbeFfdc_t structre
        size_t sbe_ffdc_size = sizeof(sbeFfdc_t);
@@ -251,7 +251,8 @@ void libekb_get_sbe_ffdc(FFDC& ffdc, const sbeFfdcPacketType& ffdc_pkt,
                } else {
                        ffdc_data.data = sbe_ffdc->data;
                }
-               ffdc_endian.push_back(ffdc_data);
+               ffdc_endian.push_back(ffdc_data.size);
+               ffdc_endian.push_back(ffdc_data.data);

This breaks because the setSbeError calls in the generated hwpf/fapi2/include/error_info/set_sbe_error.H require a sbeFfdc_t.

I think the fix is to copy the data to an intermediate buffer before creating fapi2::variable_buffer l_buffer, or create a new fapi2::variable_buffer constructor that takes a byte array.