[PATCH v2] gdb/csky support .reg2 for kernel 4.x and later
jiangshuai_li
jiangshuai_li@linux.alibaba.com
Wed Jul 27 07:29:17 GMT 2022
>> When kernel's version >= 4.x, the size of .reg2 section will be 400.
>> Contents of .reg2 are {
>> unsigned long vr[96]; // vr0~vr15 & fr16~fr31
>> unsigned long fcr;
>> unsigned long fesr;
>> unsigned long fid;
>> unsigned long reserved;
>> };
>>
>> ---
>> gdb/csky-linux-tdep.c | 150 +++++++++++++++++++++++++++++++++++++-----
>> 1 file changed, 134 insertions(+), 16 deletions(-)
>>
>> diff --git a/gdb/csky-linux-tdep.c b/gdb/csky-linux-tdep.c
>> index 440045e7713..aa85a299922 100644
>> --- a/gdb/csky-linux-tdep.c
>> +++ b/gdb/csky-linux-tdep.c
>> @@ -36,6 +36,8 @@
>> #define SIZEOF_CSKY_GREGSET 34*4
>> /* Float regset fesr fsr fr0-fr31 for CK810. */
>> #define SIZEOF_CSKY_FREGSET 34*4
>> +/* Float regset vr0~vr15 fr15~fr31, reserved for CK810 when kernel 4.x. */
>
>You might want to expand the comment above indicating that the struct
>layout can be found in a comment within csky_supply_fregset.
>
>> +#define SIZEOF_CSKY_FREGSET_K4X 400
>>
>> /* Offset mapping table from core_section to regcache of general
>> registers for ck810. */
>> @@ -118,15 +120,76 @@ csky_supply_fregset (const struct regset
>> *regset, int fregset_num = ARRAY_SIZE (csky_fregset_offset);
>>
>> gdb_assert (len >= SIZEOF_CSKY_FREGSET);
>> - for (i = 0; i < fregset_num; i++)
>> + if (len == SIZEOF_CSKY_FREGSET)
>> {
>> - if ((regnum == csky_fregset_offset[i] || regnum == -1)
>> - && csky_fregset_offset[i] != -1)
>> - {
>> - int num = csky_fregset_offset[i];
>> - offset += register_size (gdbarch, num);
>> - regcache->raw_supply (csky_fregset_offset[i], fregs +
>> offset);
>> - }
>> + for (i = 0; i < fregset_num; i++)
>> + {
>> + if ((regnum == csky_fregset_offset[i] || regnum == -1)
>> + && csky_fregset_offset[i] != -1)
>> + {
>> + int num = csky_fregset_offset[i];
>> + offset += register_size (gdbarch, num);
>> + regcache->raw_supply (csky_fregset_offset[i], fregs +
>> offset);
>> + }
>> + }
>> + }
>> + else if (len == SIZEOF_CSKY_FREGSET_K4X)
>> + {
>> + /* When kernel version >= 4.x, .reg2 size will be 400.
>> + Contents is {
>> + unsigned long vr[96]; // vr0~vr15 + fr16~fr31
>> + unsigned long fcr;
>> + unsigned long fesr;
>> + unsigned long fid;
>> + unsigned long reserved;
>> + } */
>> + int fcr_regno[] = {122, 123, 121}; /* fcr, fesr, fid. */
>> +
>> + /* Supply vr0~vr15. */
>> + for (i = 0; i < 16; i ++)
>> + {
>> + if (gdbarch_register_name (gdbarch, (CSKY_VR0_REGNUM + i)))
>> + {
>> + offset = 16 * i;
>> + regcache->raw_supply (CSKY_VR0_REGNUM + i,
>> + fregs + offset);
>> + }
>> + }
>> + /* Supply fr0~fr15. */
>> + for (i = 0; i < 16; i ++)
>> + {
>> + if (gdbarch_register_name (gdbarch, (CSKY_FR0_REGNUM + i)))
>> + {
>> + offset = 16 * i;
>
>Are these offsets correct? I.e. do the fr0~fr15 registers use
>the same offsets as vr0~vr15?
Yes. The bit width of floating-point register is 64bits, and the bit width of vector
register is 128bit. In fr0~fr15 and vr0~vr15, each FRx is the lower 64 bits of
the corresponding VRx.
>
>Also, not related to this patch, but while trying to figure this out,
>I found this line in csky-tdep.h - it looks fishy to me since it's
>way bigger than CSKY_MAX_REGS:
>
> CSKY_FR16_REGNUM = 1172,
Actually, the max regs number should be 1187, but if the gdb stub does not send a
tdesc-xml file to gdb, 253 works.
>
>It definitely matters since you refer to CSKY_FR16_REGNUM below.
>
>> + regcache->raw_supply (CSKY_FR0_REGNUM + i,
>> + fregs + offset);
>> + }
>> + }
>> + /* Supply fr16~fr31. */
>> + for (i = 0; i < 16; i ++)
>> + {
>> + if (gdbarch_register_name (gdbarch, (CSKY_FR16_REGNUM +
>> i)))
>> + {
>> + offset = (16 * 16) + (8 * i);
>> + regcache->raw_supply (CSKY_FR16_REGNUM + i,
>> + fregs + offset);
>> + }
>> + }
>> + /* Supply fcr, fesr, fid. */
>> + for (i = 0; i < 3; i ++)
>> + {
>> + if (gdbarch_register_name (gdbarch, fcr_regno[i]))
>> + {
>> + offset = (16 * 16) + (16 * 8) + (4 * i);
>> + regcache->raw_supply (fcr_regno[i],
>> + fregs + offset);
>> + }
>> + }
>> + }
>> + else
>> + {
>> + warning (_("Unknow size %ld of section .reg2, can not get
>> value"
>> + " of float registers."), len);
>> }
>> }
>>
>> @@ -144,14 +207,66 @@ csky_collect_fregset (const struct regset
>> *regset, int offset = 0;
>>
>> gdb_assert (len >= SIZEOF_CSKY_FREGSET);
>> - for (regno = 0; regno < fregset_num; regno++)
>> + if (len == SIZEOF_CSKY_FREGSET)
>> + {
>> + for (regno = 0; regno < fregset_num; regno++)
>> + {
>> + if ((regnum == csky_fregset_offset[regno] || regnum == -1)
>> + && csky_fregset_offset[regno] != -1)
>> + {
>> + offset += register_size (gdbarch,
>> csky_fregset_offset[regno]);
>> + regcache->raw_collect (regno, fregs + offset);
>> + }
>> + }
>> + }
>> + else if (len == SIZEOF_CSKY_FREGSET_K4X)
>> + {
>> + /* When kernel version >= 4.x, .reg2 size will be 400.
>> + Contents is {
>> + unsigned long vr[96]; // vr0~vr15 + fr16~fr31
>> + unsigned long fcr;
>> + unsigned long fesr;
>> + unsigned long fid;
>> + unsigned long reserved;
>> + } */
>> + int i = 0;
>> + int fcr_regno[] = {122, 123, 121}; /* fcr, fesr, fid. */
>> +
>> + /* Supply vr0~vr15. */
>> + for (i = 0; i < 16; i ++)
>> + {
>> + if (gdbarch_register_name (gdbarch, (CSKY_VR0_REGNUM + i)))
>> + {
>> + offset = 16 * i;
>> + regcache ->raw_collect (CSKY_VR0_REGNUM + i,
>> + fregs + offset);
>> + }
>> + }
>> + /* Supply fr16~fr31. */
>> + for (i = 0; i < 16; i ++)
>> + {
>> + if (gdbarch_register_name (gdbarch, (CSKY_FR16_REGNUM +
>> i)))
>> + {
>> + offset = (16 * 16) + (8 * i);
>> + regcache ->raw_collect (CSKY_FR16_REGNUM + i,
>> + fregs + offset);
>> + }
>> + }
>> + /* Supply fcr, fesr, fid. */
>> + for (i = 0; i < 3; i ++)
>> + {
>> + if (gdbarch_register_name (gdbarch, fcr_regno[i]))
>> + {
>> + offset = (16 * 16) + (16 * 8) + (4 * i);
>> + regcache ->raw_collect (fcr_regno[i],
>> + fregs + offset);
>> + }
>> + }
>> + }
>> + else
>> {
>> - if ((regnum == csky_fregset_offset[regno] || regnum == -1)
>> - && csky_fregset_offset[regno] != -1)
>> - {
>> - offset += register_size (gdbarch,
>> csky_fregset_offset[regno]);
>> - regcache->raw_collect (regno, fregs + offset);
>> - }
>> + warning (_("Unknow size %ld of section .reg2, will not set
>> value"
>> + " of float registers."), len);
>> }
>> }
>>
>> @@ -166,7 +281,10 @@ static const struct regset csky_regset_float =
>> {
>> NULL,
>> csky_supply_fregset,
>> - csky_collect_fregset
>> + csky_collect_fregset,
>> + /* Allow .reg2 has different size, buf size of .reg2 should
>> + always is or bigger than SIZEOF_CSKY_FREGSET. */
>
>I recommend a slightly different wording for the above comment:
>
> /* Allow .reg2 to have a different size, but the size of .reg2 should
> always be bigger than SIZEOF_CSKY_FREGSET. */
Get.
>
>> + 1
>> };
>>
>> /* Iterate over core file register note sections. */
>> --
>> 2.25.1
>>
Thanks Kevin Buettner.
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