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gdb/gdbserver: LoongArch: Improve implementation of fcc registers
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The current implementation of the fcc register is referenced to the
user_fp_state structure of the kernel uapi [1].

struct user_fp_state {
	uint64_t    fpr[32];
	uint64_t    fcc;
	uint32_t    fcsr;
};

But it is mistakenly defined as a 64-bit fputype register, resulting
in a confusing output of "info register".

(gdb) info register
...
fcc            {f = 0x0, d = 0x0}  {f = 0, d = 0}
...

According to "Condition Flag Register" in "LoongArch Reference Manual"
[2], there are 8 condition flag registers of size 1. Use 8 registers of
uint8 to make it easier for users to view the fcc register groups.

(gdb) info register
...
fcc0           0x1                 1
fcc1           0x0                 0
fcc2           0x0                 0
fcc3           0x0                 0
fcc4           0x0                 0
fcc5           0x0                 0
fcc6           0x0                 0
fcc7           0x0                 0
...

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/loongarch/include/uapi/asm/ptrace.h
[2] https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#_condition_flag_register

Signed-off-by: Feiyang Chen <[email protected]>
Signed-off-by: Tiezhu Yang <[email protected]>
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FreeFlyingSheep authored and Tiezhu Yang committed Aug 9, 2022
1 parent a88c79b commit ea33521
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Showing 6 changed files with 99 additions and 11 deletions.
7 changes: 4 additions & 3 deletions gdb/arch/loongarch.h
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Original file line number Diff line number Diff line change
Expand Up @@ -37,9 +37,10 @@ enum loongarch_regnum
LOONGARCH_ARG_REGNUM = 8, /* r4-r11: general-purpose argument registers.
f0-f7: floating-point argument registers. */
LOONGARCH_FIRST_FP_REGNUM = LOONGARCH_LINUX_NUM_GREGSET,
LOONGARCH_FCC_REGNUM = LOONGARCH_FIRST_FP_REGNUM + 32,
LOONGARCH_FCSR_REGNUM = LOONGARCH_FCC_REGNUM + 1,
LOONGARCH_LINUX_NUM_FPREGSET = 34,
LOONGARCH_LINUX_NUM_FPREGSET = 32,
LOONGARCH_FIRST_FCC_REGNUM = LOONGARCH_FIRST_FP_REGNUM + LOONGARCH_LINUX_NUM_FPREGSET,
LOONGARCH_LINUX_NUM_FCC = 8,
LOONGARCH_FCSR_REGNUM = LOONGARCH_FIRST_FCC_REGNUM + LOONGARCH_LINUX_NUM_FCC,
};

enum loongarch_fputype
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9 changes: 8 additions & 1 deletion gdb/features/loongarch/fpu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -49,7 +49,14 @@ create_feature_loongarch_fpu (struct target_desc *result, long regnum)
tdesc_create_reg (feature, "f29", regnum++, 1, "float", 64, "fputype");
tdesc_create_reg (feature, "f30", regnum++, 1, "float", 64, "fputype");
tdesc_create_reg (feature, "f31", regnum++, 1, "float", 64, "fputype");
tdesc_create_reg (feature, "fcc", regnum++, 1, "float", 64, "fputype");
tdesc_create_reg (feature, "fcc0", regnum++, 1, "float", 8, "uint8");
tdesc_create_reg (feature, "fcc1", regnum++, 1, "float", 8, "uint8");
tdesc_create_reg (feature, "fcc2", regnum++, 1, "float", 8, "uint8");
tdesc_create_reg (feature, "fcc3", regnum++, 1, "float", 8, "uint8");
tdesc_create_reg (feature, "fcc4", regnum++, 1, "float", 8, "uint8");
tdesc_create_reg (feature, "fcc5", regnum++, 1, "float", 8, "uint8");
tdesc_create_reg (feature, "fcc6", regnum++, 1, "float", 8, "uint8");
tdesc_create_reg (feature, "fcc7", regnum++, 1, "float", 8, "uint8");
tdesc_create_reg (feature, "fcsr", regnum++, 1, "float", 32, "uint32");
return regnum;
}
9 changes: 8 additions & 1 deletion gdb/features/loongarch/fpu.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,13 @@
<reg name="f29" bitsize="64" type="fputype" group="float"/>
<reg name="f30" bitsize="64" type="fputype" group="float"/>
<reg name="f31" bitsize="64" type="fputype" group="float"/>
<reg name="fcc" bitsize="64" type="fputype" group="float"/>
<reg name="fcc0" bitsize="8" type="uint8" group="float"/>
<reg name="fcc1" bitsize="8" type="uint8" group="float"/>
<reg name="fcc2" bitsize="8" type="uint8" group="float"/>
<reg name="fcc3" bitsize="8" type="uint8" group="float"/>
<reg name="fcc4" bitsize="8" type="uint8" group="float"/>
<reg name="fcc5" bitsize="8" type="uint8" group="float"/>
<reg name="fcc6" bitsize="8" type="uint8" group="float"/>
<reg name="fcc7" bitsize="8" type="uint8" group="float"/>
<reg name="fcsr" bitsize="32" type="uint32" group="float"/>
</feature>
55 changes: 51 additions & 4 deletions gdb/loongarch-linux-tdep.c
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Original file line number Diff line number Diff line change
Expand Up @@ -123,6 +123,7 @@ loongarch_supply_fpregset (const struct regset *r,
{
const gdb_byte *buf = nullptr;
int fprsize = register_size (regcache->arch (), LOONGARCH_FIRST_FP_REGNUM);
int fccsize = register_size (regcache->arch (), LOONGARCH_FIRST_FCC_REGNUM);

if (regnum == -1)
{
Expand All @@ -131,12 +132,33 @@ loongarch_supply_fpregset (const struct regset *r,
buf = (const gdb_byte *)fprs + fprsize * i;
regcache->raw_supply (LOONGARCH_FIRST_FP_REGNUM + i, (const void *)buf);
}
for (int i = 0; i < LOONGARCH_LINUX_NUM_FCC; i++)
{
buf = (const gdb_byte *)fprs + fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * i;
regcache->raw_supply (LOONGARCH_FIRST_FCC_REGNUM + i, (const void *)buf);
}
buf = (const gdb_byte *)fprs + fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * LOONGARCH_LINUX_NUM_FCC;
regcache->raw_supply (LOONGARCH_FCSR_REGNUM, (const void *)buf);
}
else if (regnum >= LOONGARCH_FIRST_FP_REGNUM && regnum <= LOONGARCH_FCSR_REGNUM)
else if (regnum >= LOONGARCH_FIRST_FP_REGNUM && regnum < LOONGARCH_FIRST_FCC_REGNUM)
{
buf = (const gdb_byte *)fprs + fprsize * (regnum - LOONGARCH_FIRST_FP_REGNUM);
regcache->raw_supply (regnum, (const void *)buf);
}
else if (regnum >= LOONGARCH_FIRST_FCC_REGNUM && regnum < LOONGARCH_FCSR_REGNUM)
{
buf = (const gdb_byte *)fprs + fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * (regnum - LOONGARCH_FIRST_FCC_REGNUM);
regcache->raw_supply (regnum, (const void *)buf);
}
else if (regnum == LOONGARCH_FCSR_REGNUM)
{
buf = (const gdb_byte *)fprs + fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * LOONGARCH_LINUX_NUM_FCC;
regcache->raw_supply (regnum, (const void *)buf);
}
}

/* Pack the GDB's register cache value into an elf_fpregset_t. */
Expand All @@ -147,6 +169,7 @@ loongarch_fill_fpregset (const struct regset *r,
{
gdb_byte *buf = nullptr;
int fprsize = register_size (regcache->arch (), LOONGARCH_FIRST_FP_REGNUM);
int fccsize = register_size (regcache->arch (), LOONGARCH_FIRST_FCC_REGNUM);

if (regnum == -1)
{
Expand All @@ -155,12 +178,33 @@ loongarch_fill_fpregset (const struct regset *r,
buf = (gdb_byte *)fprs + fprsize * i;
regcache->raw_collect (LOONGARCH_FIRST_FP_REGNUM + i, (void *)buf);
}
for (int i = 0; i < LOONGARCH_LINUX_NUM_FCC; i++)
{
buf = (gdb_byte *)fprs + fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * i;
regcache->raw_collect (LOONGARCH_FIRST_FCC_REGNUM + i, (void *)buf);
}
buf = (gdb_byte *)fprs + fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * LOONGARCH_LINUX_NUM_FCC;
regcache->raw_collect (LOONGARCH_FCSR_REGNUM, (void *)buf);
}
else if (regnum >= LOONGARCH_FIRST_FP_REGNUM && regnum <= LOONGARCH_FCSR_REGNUM)
else if (regnum >= LOONGARCH_FIRST_FP_REGNUM && regnum < LOONGARCH_FIRST_FCC_REGNUM)
{
buf = (gdb_byte *)fprs + fprsize * (regnum - LOONGARCH_FIRST_FP_REGNUM);
regcache->raw_collect (regnum, (void *)buf);
}
else if (regnum >= LOONGARCH_FIRST_FCC_REGNUM && regnum < LOONGARCH_FCSR_REGNUM)
{
buf = (gdb_byte *)fprs + fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * (regnum - LOONGARCH_FIRST_FCC_REGNUM);
regcache->raw_collect (regnum, (void *)buf);
}
else if (regnum == LOONGARCH_FCSR_REGNUM)
{
buf = (gdb_byte *)fprs + fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * LOONGARCH_LINUX_NUM_FCC;
regcache->raw_collect (regnum, (void *)buf);
}
}

/* Define the FP register regset. */
Expand Down Expand Up @@ -221,11 +265,14 @@ loongarch_iterate_over_regset_sections (struct gdbarch *gdbarch,
{
int gprsize = register_size (gdbarch, 0);
int fprsize = register_size (gdbarch, LOONGARCH_FIRST_FP_REGNUM);
int fccsize = register_size (gdbarch, LOONGARCH_FIRST_FCC_REGNUM);
int fcsrsize = register_size (gdbarch, LOONGARCH_FCSR_REGNUM);
int fpsize = fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * LOONGARCH_LINUX_NUM_FCC + fcsrsize;

cb (".reg", LOONGARCH_LINUX_NUM_GREGSET * gprsize,
LOONGARCH_LINUX_NUM_GREGSET * gprsize, &loongarch_gregset, nullptr, cb_data);
cb (".reg2", LOONGARCH_LINUX_NUM_FPREGSET * fprsize,
LOONGARCH_LINUX_NUM_FPREGSET * fprsize, &loongarch_fpregset, nullptr, cb_data);
cb (".reg2", fpsize, fpsize, &loongarch_fpregset, nullptr, cb_data);
}

/* The following value is derived from __NR_rt_sigreturn in
Expand Down
6 changes: 4 additions & 2 deletions gdb/loongarch-tdep.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1428,10 +1428,12 @@ loongarch_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
/* Validate the description provides the fpu registers and
allocate their numbers. */
regnum = LOONGARCH_FIRST_FP_REGNUM;
for (int i = 0; i < 32; i++)
for (int i = 0; i < LOONGARCH_LINUX_NUM_FPREGSET; i++)
valid_p &= tdesc_numbered_register (feature_fpu, tdesc_data.get (), regnum++,
loongarch_f_normal_name[i] + 1);
valid_p &= tdesc_numbered_register (feature_fpu, tdesc_data.get (), regnum++, "fcc");
for (int i = 0; i < LOONGARCH_LINUX_NUM_FCC; i++)
valid_p &= tdesc_numbered_register (feature_fpu, tdesc_data.get (), regnum++,
loongarch_c_normal_name[i] + 1);
valid_p &= tdesc_numbered_register (feature_fpu, tdesc_data.get (), regnum++, "fcsr");
if (!valid_p)
return nullptr;
Expand Down
24 changes: 24 additions & 0 deletions gdbserver/linux-loongarch-low.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -127,12 +127,24 @@ loongarch_fill_fpregset (struct regcache *regcache, void *buf)
{
gdb_byte *regbuf = nullptr;
int fprsize = register_size (regcache->tdesc, LOONGARCH_FIRST_FP_REGNUM);
int fccsize = register_size (regcache->tdesc, LOONGARCH_FIRST_FCC_REGNUM);

for (int i = 0; i < LOONGARCH_LINUX_NUM_FPREGSET; i++)
{
regbuf = (gdb_byte *)buf + fprsize * i;
collect_register (regcache, LOONGARCH_FIRST_FP_REGNUM + i, regbuf);
}

for (int i = 0; i < LOONGARCH_LINUX_NUM_FCC; i++)
{
regbuf = (gdb_byte *)buf + fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * i;
collect_register (regcache, LOONGARCH_FIRST_FCC_REGNUM + i, regbuf);
}

regbuf = (gdb_byte *)buf + fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * LOONGARCH_LINUX_NUM_FCC;
collect_register (regcache, LOONGARCH_FCSR_REGNUM, regbuf);
}

/* Supply FPRs from BUF into REGCACHE. */
Expand All @@ -142,12 +154,24 @@ loongarch_store_fpregset (struct regcache *regcache, const void *buf)
{
const gdb_byte *regbuf = nullptr;
int fprsize = register_size (regcache->tdesc, LOONGARCH_FIRST_FP_REGNUM);
int fccsize = register_size (regcache->tdesc, LOONGARCH_FIRST_FCC_REGNUM);

for (int i = 0; i < LOONGARCH_LINUX_NUM_FPREGSET; i++)
{
regbuf = (const gdb_byte *)buf + fprsize * i;
supply_register (regcache, LOONGARCH_FIRST_FP_REGNUM + i, regbuf);
}

for (int i = 0; i < LOONGARCH_LINUX_NUM_FCC; i++)
{
regbuf = (const gdb_byte *)buf + fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * i;
supply_register (regcache, LOONGARCH_FIRST_FCC_REGNUM + i, regbuf);
}

regbuf = (const gdb_byte *)buf + fprsize * LOONGARCH_LINUX_NUM_FPREGSET +
fccsize * LOONGARCH_LINUX_NUM_FCC;
supply_register (regcache, LOONGARCH_FCSR_REGNUM, regbuf);
}

/* LoongArch/Linux regsets. */
Expand Down

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