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MIPS: Support for 64-bit FP with O32 binaries

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CPUs implementing MIPS32 R2 may include a 64-bit FPU, just as MIPS64 CPUs
do. In order to preserve backwards compatibility a 64-bit FPU will act
like a 32-bit FPU (by accessing doubles from the least significant 32
bits of an even-odd pair of FP registers) when the Status.FR bit is
zero, again just like a mips64 CPU. The standard O32 ABI is defined
expecting a 32-bit FPU, however recent toolchains support use of a
64-bit FPU from an O32 MIPS32 executable. When an ELF executable is
built to use a 64-bit FPU a new flag (EF_MIPS_FP64) is set in the ELF
header.

With this patch the kernel will check the EF_MIPS_FP64 flag when
executing an O32 binary, and set Status.FR accordingly. The addition
of O32 64-bit FP support lessens the opportunity for optimisation in
the FPU emulator, so a CONFIG_MIPS_O32_FP64_SUPPORT Kconfig option is
introduced to allow this support to be disabled for those that don't
require it.

Inspired by an earlier patch by Leonid Yegoshin, but implemented more
cleanly & correctly.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Paul Burton <paul.burton@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/6154/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Paul Burton
2013-11-22 13:12:07 +00:00
committed by Ralf Baechle
parent 56a22d21bf
commit 597ce1723e
19 changed files with 449 additions and 236 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
arch/mips/kernel/binfmt_elfo32.c
View File

@@ -27,6 +27,18 @@ typedef elf_greg_t elf_gregset_t[ELF_NGREG];
typedef double elf_fpreg_t;
typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
/*
* In order to be sure that we don't attempt to execute an O32 binary which
* requires 64 bit FP (FR=1) on a system which does not support it we refuse
* to execute any binary which has bits specified by the following macro set
* in its ELF header flags.
*/
#ifdef CONFIG_MIPS_O32_FP64_SUPPORT
# define __MIPS_O32_FP64_MUST_BE_ZERO 0
#else
# define __MIPS_O32_FP64_MUST_BE_ZERO EF_MIPS_FP64
#endif
/*
* This is used to ensure we don't load something for the wrong architecture.
*/
@@ -43,6 +55,8 @@ typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
__res = 0; \
if (((__h->e_flags & EF_MIPS_ABI) != 0) && \
((__h->e_flags & EF_MIPS_ABI) != EF_MIPS_ABI_O32)) \
__res = 0; \
if (__h->e_flags & __MIPS_O32_FP64_MUST_BE_ZERO) \
__res = 0; \
\
__res; \

2
arch/mips/kernel/cpu-probe.c
View File

@@ -112,7 +112,7 @@ static inline unsigned long cpu_get_fpu_id(void)
unsigned long tmp, fpu_id;
tmp = read_c0_status();
__enable_fpu();
__enable_fpu(FPU_AS_IS);
fpu_id = read_32bit_cp1_register(CP1_REVISION);
write_c0_status(tmp);
return fpu_id;

3
arch/mips/kernel/process.c
View File

@@ -60,9 +60,6 @@ void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
/* New thread loses kernel privileges. */
status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
#ifdef CONFIG_64BIT
status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR;
#endif
status |= KU_USER;
regs->cp0_status = status;
clear_used_math();

60
arch/mips/kernel/ptrace.c
View File

@@ -137,13 +137,13 @@ int ptrace_getfpregs(struct task_struct *child, __u32 __user *data)
if (cpu_has_mipsmt) {
unsigned int vpflags = dvpe();
flags = read_c0_status();
__enable_fpu();
__enable_fpu(FPU_AS_IS);
__asm__ __volatile__("cfc1\t%0,$0" : "=r" (tmp));
write_c0_status(flags);
evpe(vpflags);
} else {
flags = read_c0_status();
__enable_fpu();
__enable_fpu(FPU_AS_IS);
__asm__ __volatile__("cfc1\t%0,$0" : "=r" (tmp));
write_c0_status(flags);
}
@@ -408,6 +408,7 @@ long arch_ptrace(struct task_struct *child, long request,
/* Read the word at location addr in the USER area. */
case PTRACE_PEEKUSR: {
struct pt_regs *regs;
fpureg_t *fregs;
unsigned long tmp = 0;
regs = task_pt_regs(child);
@@ -418,26 +419,28 @@ long arch_ptrace(struct task_struct *child, long request,
tmp = regs->regs[addr];
break;
case FPR_BASE ... FPR_BASE + 31:
if (tsk_used_math(child)) {
fpureg_t *fregs = get_fpu_regs(child);
if (!tsk_used_math(child)) {
/* FP not yet used */
tmp = -1;
break;
}
fregs = get_fpu_regs(child);
#ifdef CONFIG_32BIT
if (test_thread_flag(TIF_32BIT_FPREGS)) {
/*
* The odd registers are actually the high
* order bits of the values stored in the even
* registers - unless we're using r2k_switch.S.
*/
if (addr & 1)
tmp = (unsigned long) (fregs[((addr & ~1) - 32)] >> 32);
tmp = fregs[(addr & ~1) - 32] >> 32;
else
tmp = (unsigned long) (fregs[(addr - 32)] & 0xffffffff);
#endif
#ifdef CONFIG_64BIT
tmp = fregs[addr - FPR_BASE];
#endif
} else {
tmp = -1; /* FP not yet used */
tmp = fregs[addr - 32];
break;
}
#endif
tmp = fregs[addr - FPR_BASE];
break;
case PC:
tmp = regs->cp0_epc;
@@ -483,13 +486,13 @@ long arch_ptrace(struct task_struct *child, long request,
if (cpu_has_mipsmt) {
unsigned int vpflags = dvpe();
flags = read_c0_status();
__enable_fpu();
__enable_fpu(FPU_AS_IS);
__asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
write_c0_status(flags);
evpe(vpflags);
} else {
flags = read_c0_status();
__enable_fpu();
__enable_fpu(FPU_AS_IS);
__asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
write_c0_status(flags);
}
@@ -554,22 +557,25 @@ long arch_ptrace(struct task_struct *child, long request,
child->thread.fpu.fcr31 = 0;
}
#ifdef CONFIG_32BIT
/*
* The odd registers are actually the high order bits
* of the values stored in the even registers - unless
* we're using r2k_switch.S.
*/
if (addr & 1) {
fregs[(addr & ~1) - FPR_BASE] &= 0xffffffff;
fregs[(addr & ~1) - FPR_BASE] |= ((unsigned long long) data) << 32;
} else {
fregs[addr - FPR_BASE] &= ~0xffffffffLL;
fregs[addr - FPR_BASE] |= data;
if (test_thread_flag(TIF_32BIT_FPREGS)) {
/*
* The odd registers are actually the high
* order bits of the values stored in the even
* registers - unless we're using r2k_switch.S.
*/
if (addr & 1) {
fregs[(addr & ~1) - FPR_BASE] &=
0xffffffff;
fregs[(addr & ~1) - FPR_BASE] |=
((u64)data) << 32;
} else {
fregs[addr - FPR_BASE] &= ~0xffffffffLL;
fregs[addr - FPR_BASE] |= data;
}
break;
}
#endif
#ifdef CONFIG_64BIT
fregs[addr - FPR_BASE] = data;
#endif
break;
}
case PC:

53
arch/mips/kernel/ptrace32.c
View File

@@ -80,6 +80,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
/* Read the word at location addr in the USER area. */
case PTRACE_PEEKUSR: {
struct pt_regs *regs;
fpureg_t *fregs;
unsigned int tmp;
regs = task_pt_regs(child);
@@ -90,21 +91,25 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
tmp = regs->regs[addr];
break;
case FPR_BASE ... FPR_BASE + 31:
if (tsk_used_math(child)) {
fpureg_t *fregs = get_fpu_regs(child);
if (!tsk_used_math(child)) {
/* FP not yet used */
tmp = -1;
break;
}
fregs = get_fpu_regs(child);
if (test_thread_flag(TIF_32BIT_FPREGS)) {
/*
* The odd registers are actually the high
* order bits of the values stored in the even
* registers - unless we're using r2k_switch.S.
*/
if (addr & 1)
tmp = (unsigned long) (fregs[((addr & ~1) - 32)] >> 32);
tmp = fregs[(addr & ~1) - 32] >> 32;
else
tmp = (unsigned long) (fregs[(addr - 32)] & 0xffffffff);
} else {
tmp = -1; /* FP not yet used */
tmp = fregs[addr - 32];
break;
}
tmp = fregs[addr - FPR_BASE];
break;
case PC:
tmp = regs->cp0_epc;
@@ -147,13 +152,13 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
if (cpu_has_mipsmt) {
unsigned int vpflags = dvpe();
flags = read_c0_status();
__enable_fpu();
__enable_fpu(FPU_AS_IS);
__asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
write_c0_status(flags);
evpe(vpflags);
} else {
flags = read_c0_status();
__enable_fpu();
__enable_fpu(FPU_AS_IS);
__asm__ __volatile__("cfc1\t%0,$0": "=r" (tmp));
write_c0_status(flags);
}
@@ -236,20 +241,24 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
sizeof(child->thread.fpu));
child->thread.fpu.fcr31 = 0;
}
/*
* The odd registers are actually the high order bits
* of the values stored in the even registers - unless
* we're using r2k_switch.S.
*/
if (addr & 1) {
fregs[(addr & ~1) - FPR_BASE] &= 0xffffffff;
fregs[(addr & ~1) - FPR_BASE] |= ((unsigned long long) data) << 32;
} else {
fregs[addr - FPR_BASE] &= ~0xffffffffLL;
/* Must cast, lest sign extension fill upper
bits! */
fregs[addr - FPR_BASE] |= (unsigned int)data;
if (test_thread_flag(TIF_32BIT_FPREGS)) {
/*
* The odd registers are actually the high
* order bits of the values stored in the even
* registers - unless we're using r2k_switch.S.
*/
if (addr & 1) {
fregs[(addr & ~1) - FPR_BASE] &=
0xffffffff;
fregs[(addr & ~1) - FPR_BASE] |=
((u64)data) << 32;
} else {
fregs[addr - FPR_BASE] &= ~0xffffffffLL;
fregs[addr - FPR_BASE] |= data;
}
break;
}
fregs[addr - FPR_BASE] = data;
break;
}
case PC:

74
arch/mips/kernel/r4k_fpu.S
View File

@@ -35,7 +35,15 @@
LEAF(_save_fp_context)
cfc1 t1, fcr31
#ifdef CONFIG_64BIT
#if defined(CONFIG_64BIT) || defined(CONFIG_MIPS32_R2)
.set push
#ifdef CONFIG_MIPS32_R2
.set mips64r2
mfc0 t0, CP0_STATUS
sll t0, t0, 5
bgez t0, 1f # skip storing odd if FR=0
nop
#endif
/* Store the 16 odd double precision registers */
EX sdc1 $f1, SC_FPREGS+8(a0)
EX sdc1 $f3, SC_FPREGS+24(a0)
@@ -53,6 +61,7 @@ LEAF(_save_fp_context)
EX sdc1 $f27, SC_FPREGS+216(a0)
EX sdc1 $f29, SC_FPREGS+232(a0)
EX sdc1 $f31, SC_FPREGS+248(a0)
1: .set pop
#endif
/* Store the 16 even double precision registers */
@@ -82,7 +91,31 @@ LEAF(_save_fp_context)
LEAF(_save_fp_context32)
cfc1 t1, fcr31
EX sdc1 $f0, SC32_FPREGS+0(a0)
mfc0 t0, CP0_STATUS
sll t0, t0, 5
bgez t0, 1f # skip storing odd if FR=0
nop
/* Store the 16 odd double precision registers */
EX sdc1 $f1, SC32_FPREGS+8(a0)
EX sdc1 $f3, SC32_FPREGS+24(a0)
EX sdc1 $f5, SC32_FPREGS+40(a0)
EX sdc1 $f7, SC32_FPREGS+56(a0)
EX sdc1 $f9, SC32_FPREGS+72(a0)
EX sdc1 $f11, SC32_FPREGS+88(a0)
EX sdc1 $f13, SC32_FPREGS+104(a0)
EX sdc1 $f15, SC32_FPREGS+120(a0)
EX sdc1 $f17, SC32_FPREGS+136(a0)
EX sdc1 $f19, SC32_FPREGS+152(a0)
EX sdc1 $f21, SC32_FPREGS+168(a0)
EX sdc1 $f23, SC32_FPREGS+184(a0)
EX sdc1 $f25, SC32_FPREGS+200(a0)
EX sdc1 $f27, SC32_FPREGS+216(a0)
EX sdc1 $f29, SC32_FPREGS+232(a0)
EX sdc1 $f31, SC32_FPREGS+248(a0)
/* Store the 16 even double precision registers */
1: EX sdc1 $f0, SC32_FPREGS+0(a0)
EX sdc1 $f2, SC32_FPREGS+16(a0)
EX sdc1 $f4, SC32_FPREGS+32(a0)
EX sdc1 $f6, SC32_FPREGS+48(a0)
@@ -114,7 +147,16 @@ LEAF(_save_fp_context32)
*/
LEAF(_restore_fp_context)
EX lw t0, SC_FPC_CSR(a0)
#ifdef CONFIG_64BIT
#if defined(CONFIG_64BIT) || defined(CONFIG_MIPS32_R2)
.set push
#ifdef CONFIG_MIPS32_R2
.set mips64r2
mfc0 t0, CP0_STATUS
sll t0, t0, 5
bgez t0, 1f # skip loading odd if FR=0
nop
#endif
EX ldc1 $f1, SC_FPREGS+8(a0)
EX ldc1 $f3, SC_FPREGS+24(a0)
EX ldc1 $f5, SC_FPREGS+40(a0)
@@ -131,6 +173,7 @@ LEAF(_restore_fp_context)
EX ldc1 $f27, SC_FPREGS+216(a0)
EX ldc1 $f29, SC_FPREGS+232(a0)
EX ldc1 $f31, SC_FPREGS+248(a0)
1: .set pop
#endif
EX ldc1 $f0, SC_FPREGS+0(a0)
EX ldc1 $f2, SC_FPREGS+16(a0)
@@ -157,7 +200,30 @@ LEAF(_restore_fp_context)
LEAF(_restore_fp_context32)
/* Restore an o32 sigcontext. */
EX lw t0, SC32_FPC_CSR(a0)
EX ldc1 $f0, SC32_FPREGS+0(a0)
mfc0 t0, CP0_STATUS
sll t0, t0, 5
bgez t0, 1f # skip loading odd if FR=0
nop
EX ldc1 $f1, SC32_FPREGS+8(a0)
EX ldc1 $f3, SC32_FPREGS+24(a0)
EX ldc1 $f5, SC32_FPREGS+40(a0)
EX ldc1 $f7, SC32_FPREGS+56(a0)
EX ldc1 $f9, SC32_FPREGS+72(a0)
EX ldc1 $f11, SC32_FPREGS+88(a0)
EX ldc1 $f13, SC32_FPREGS+104(a0)
EX ldc1 $f15, SC32_FPREGS+120(a0)
EX ldc1 $f17, SC32_FPREGS+136(a0)
EX ldc1 $f19, SC32_FPREGS+152(a0)
EX ldc1 $f21, SC32_FPREGS+168(a0)
EX ldc1 $f23, SC32_FPREGS+184(a0)
EX ldc1 $f25, SC32_FPREGS+200(a0)
EX ldc1 $f27, SC32_FPREGS+216(a0)
EX ldc1 $f29, SC32_FPREGS+232(a0)
EX ldc1 $f31, SC32_FPREGS+248(a0)
1: EX ldc1 $f0, SC32_FPREGS+0(a0)
EX ldc1 $f2, SC32_FPREGS+16(a0)
EX ldc1 $f4, SC32_FPREGS+32(a0)
EX ldc1 $f6, SC32_FPREGS+48(a0)

45
arch/mips/kernel/r4k_switch.S
View File

@@ -123,7 +123,7 @@
* Save a thread's fp context.
*/
LEAF(_save_fp)
#ifdef CONFIG_64BIT
#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPS32_R2)
mfc0 t0, CP0_STATUS
#endif
fpu_save_double a0 t0 t1 # clobbers t1
@@ -134,7 +134,7 @@ LEAF(_save_fp)
* Restore a thread's fp context.
*/
LEAF(_restore_fp)
#ifdef CONFIG_64BIT
#if defined(CONFIG_64BIT) || defined(CONFIG_CPU_MIPS32_R2)
mfc0 t0, CP0_STATUS
#endif
fpu_restore_double a0 t0 t1 # clobbers t1
@@ -228,6 +228,47 @@ LEAF(_init_fpu)
mtc1 t1, $f29
mtc1 t1, $f30
mtc1 t1, $f31
#ifdef CONFIG_CPU_MIPS32_R2
.set push
.set mips64r2
sll t0, t0, 5 # is Status.FR set?
bgez t0, 1f # no: skip setting upper 32b
mthc1 t1, $f0
mthc1 t1, $f1
mthc1 t1, $f2
mthc1 t1, $f3
mthc1 t1, $f4
mthc1 t1, $f5
mthc1 t1, $f6
mthc1 t1, $f7
mthc1 t1, $f8
mthc1 t1, $f9
mthc1 t1, $f10
mthc1 t1, $f11
mthc1 t1, $f12
mthc1 t1, $f13
mthc1 t1, $f14
mthc1 t1, $f15
mthc1 t1, $f16
mthc1 t1, $f17
mthc1 t1, $f18
mthc1 t1, $f19
mthc1 t1, $f20
mthc1 t1, $f21
mthc1 t1, $f22
mthc1 t1, $f23
mthc1 t1, $f24
mthc1 t1, $f25
mthc1 t1, $f26
mthc1 t1, $f27
mthc1 t1, $f28
mthc1 t1, $f29
mthc1 t1, $f30
mthc1 t1, $f31
1: .set pop
#endif /* CONFIG_CPU_MIPS32_R2 */
#else
.set mips3
dmtc1 t1, $f0

10
arch/mips/kernel/signal.c
View File

@@ -71,8 +71,9 @@ static int protected_save_fp_context(struct sigcontext __user *sc)
int err;
while (1) {
lock_fpu_owner();
own_fpu_inatomic(1);
err = save_fp_context(sc); /* this might fail */
err = own_fpu_inatomic(1);
if (!err)
err = save_fp_context(sc); /* this might fail */
unlock_fpu_owner();
if (likely(!err))
break;
@@ -91,8 +92,9 @@ static int protected_restore_fp_context(struct sigcontext __user *sc)
int err, tmp __maybe_unused;
while (1) {
lock_fpu_owner();
own_fpu_inatomic(0);
err = restore_fp_context(sc); /* this might fail */
err = own_fpu_inatomic(0);
if (!err)
err = restore_fp_context(sc); /* this might fail */
unlock_fpu_owner();
if (likely(!err))
break;

10
arch/mips/kernel/signal32.c
View File

@@ -85,8 +85,9 @@ static int protected_save_fp_context32(struct sigcontext32 __user *sc)
int err;
while (1) {
lock_fpu_owner();
own_fpu_inatomic(1);
err = save_fp_context32(sc); /* this might fail */
err = own_fpu_inatomic(1);
if (!err)
err = save_fp_context32(sc); /* this might fail */
unlock_fpu_owner();
if (likely(!err))
break;
@@ -105,8 +106,9 @@ static int protected_restore_fp_context32(struct sigcontext32 __user *sc)
int err, tmp __maybe_unused;
while (1) {
lock_fpu_owner();
own_fpu_inatomic(0);
err = restore_fp_context32(sc); /* this might fail */
err = own_fpu_inatomic(0);
if (!err)
err = restore_fp_context32(sc); /* this might fail */
unlock_fpu_owner();
if (likely(!err))
break;

10
arch/mips/kernel/traps.c
View File

@@ -1080,7 +1080,7 @@ asmlinkage void do_cpu(struct pt_regs *regs)
unsigned long old_epc, old31;
unsigned int opcode;
unsigned int cpid;
int status;
int status, err;
unsigned long __maybe_unused flags;
prev_state = exception_enter();
@@ -1153,19 +1153,19 @@ asmlinkage void do_cpu(struct pt_regs *regs)
case 1:
if (used_math()) /* Using the FPU again. */
own_fpu(1);
err = own_fpu(1);
else { /* First time FPU user. */
init_fpu();
err = init_fpu();
set_used_math();
}
if (!raw_cpu_has_fpu) {
if (!raw_cpu_has_fpu || err) {
int sig;
void __user *fault_addr = NULL;
sig = fpu_emulator_cop1Handler(regs,
&current->thread.fpu,
0, &fault_addr);
if (!process_fpemu_return(sig, fault_addr))
if (!process_fpemu_return(sig, fault_addr) && !err)
mt_ase_fp_affinity();
}