Re: [PATCH v2] add powerpc64 port

[Szabolcs Nagy <nsz@port70.net>]

* Bobby Bingham <koorogi@koorogi.info> [2016-04-04 00:26:11 -0500]:
> +++ b/arch/powerpc64/bits/setjmp.h
> @@ -0,0 +1 @@
> +typedef unsigned long long __jmp_buf[66];

hm glibc seems to use long[64] with 16byte alignment,
is the size diff because of alignment?

> +#if defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
> +#define MINSIGSTKSZ 2048
> +#define SIGSTKSZ    8192
> +#endif

i think these should be bigger, e.g. follow ppc 4k, 10k

> +typedef struct {
> +	unsigned long vrregs[32][2];
> +	unsigned _pad[3];
> +	unsigned vrsave;
> +	unsigned vscr;
> +	unsigned _pad2[3];
> +} vrregset_t;

it seems this type should be 16 byte aligned like elf_vrreg_t

(aarch64 has a similar issue i plan to fix: there we use
128bit long double to get correct alignment, but kernel
and glibc uses __int128 which is visible in public headers.
in powerpc64 at least __vector128 is not exposed in glibc,
only 16byte aligned structs.)

> +++ b/arch/powerpc64/bits/syscall.h
> @@ -0,0 +1,718 @@
> +#define __NR_restart_syscall          0
> +#define __NR_exit                     1
> +#define __NR_fork                     2
...
> +#define SYS_restart_syscall __NR_restart_syscall
> +#define SYS_exit __NR_exit
> +#define SYS_fork __NR_fork

i prefer SYS_ to use numbers too (easier to update for me),
but it should be probably fixed together across archs.

> +++ b/arch/powerpc64/reloc.h
> @@ -0,0 +1,32 @@
> +#include <endian.h>
> +
> +#if __BYTE_ORDER == __LITTLE_ENDIAN
> +#define ENDIAN_SUFFIX "le"
> +#else
> +#define ENDIAN_SUFFIX ""
> +#endif
> +
> +#define LDSO_ARCH "powerpc64" ENDIAN_SUFFIX
> +

gcc also has -sf, i'm not sure if we should care about
ppc64 soft-float

> +#define TPOFF_K (-0x7000)
> +
> +#define REL_SYMBOLIC    R_PPC64_ADDR64
> +#define REL_GOT         R_PPC64_GLOB_DAT
> +#define REL_PLT         R_PPC64_JMP_SLOT
> +#define REL_RELATIVE    R_PPC64_RELATIVE
> +#define REL_COPY        R_PPC64_COPY
> +#define REL_DTPMOD      R_PPC64_DTPMOD64
> +#define REL_DTPOFF      R_PPC64_DTPREL64
> +#define REL_TPOFF       R_PPC64_TPREL64

this reminds me that ppc(64) now has a tls optimization
if the module is tagged with DT_PPC(64)_OPT, we don't
need to implement it yet, but eventually elf.h should
be updated.

> +++ b/src/fenv/powerpc64/fenv.c
> @@ -0,0 +1,68 @@
> +#define _GNU_SOURCE
> +#include <fenv.h>
> +
> +static inline double get_fpscr_f(void)
> +{
> +	double d;
> +	__asm__ __volatile__("mffs %0" : "=d"(d));
> +	return d;
> +}
> +
> +static inline long get_fpscr(void)
> +{
> +	return (union {double f; long i;}) {get_fpscr_f()}.i;
> +}
> +
> +static inline void set_fpscr_f(double fpscr)
> +{
> +	__asm__ __volatile__("mtfsf 255, %0" : : "d"(fpscr));
> +}
> +
> +static void set_fpscr(long fpscr)
> +{
> +	set_fpscr_f((union {long i; double f;}) {fpscr}.f);
> +}
> +

yes now that .c is allowed under arch/ dirs, it
makes sense to do fenv with such set/get_fpscr

otherwise the patch looked good.