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riscv: Add support to no-FPU systems

Sfoglia il codice sorgente 
This patchset adds an option, CONFIG_FPU, to enable/disable floating-
point support within the kernel.  The kernel's new behavior will be as
follows:

* with CONFIG_FPU=y
  All FPU codes are reserved.  If no FPU is found during booting, a
  global flag will be set, and those functions will be bypassed with
  condition check to that flag.

* with CONFIG_FPU=n
  No floating-point instructions in kernel and all related settings
  are excluded.

Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This commit is contained in:
Palmer Dabbelt
2018-10-22 17:38:26 -07:00
parent aef53f97b5 9411ec60c2
commit 4e4101cfef
9 ha cambiato i file con 201 aggiunte e 132 eliminazioni
Scarica il file Patch Scarica il file Diff Expand all files Collapse all files

1
arch/riscv/kernel/Makefile
Vedi File

@@ -31,6 +31,7 @@ obj-y += vdso/
CFLAGS_setup.o := -mcmodel=medany
obj-$(CONFIG_FPU) += fpu.o
obj-$(CONFIG_SMP) += smpboot.o
obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_MODULES) += module.o

8
arch/riscv/kernel/cpufeature.c
Vedi File

@@ -22,6 +22,9 @@
#include <asm/hwcap.h>
unsigned long elf_hwcap __read_mostly;
#ifdef CONFIG_FPU
bool has_fpu __read_mostly;
#endif
void riscv_fill_hwcap(void)
{
@@ -65,4 +68,9 @@ void riscv_fill_hwcap(void)
}
pr_info("elf_hwcap is 0x%lx", elf_hwcap);
#ifdef CONFIG_FPU
if (elf_hwcap & (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D))
has_fpu = true;
#endif
}

87
arch/riscv/kernel/entry.S
Vedi File

@@ -357,93 +357,6 @@ ENTRY(__switch_to)
ret
ENDPROC(__switch_to)
ENTRY(__fstate_save)
li a2, TASK_THREAD_F0
add a0, a0, a2
li t1, SR_FS
csrs sstatus, t1
frcsr t0
fsd f0, TASK_THREAD_F0_F0(a0)
fsd f1, TASK_THREAD_F1_F0(a0)
fsd f2, TASK_THREAD_F2_F0(a0)
fsd f3, TASK_THREAD_F3_F0(a0)
fsd f4, TASK_THREAD_F4_F0(a0)
fsd f5, TASK_THREAD_F5_F0(a0)
fsd f6, TASK_THREAD_F6_F0(a0)
fsd f7, TASK_THREAD_F7_F0(a0)
fsd f8, TASK_THREAD_F8_F0(a0)
fsd f9, TASK_THREAD_F9_F0(a0)
fsd f10, TASK_THREAD_F10_F0(a0)
fsd f11, TASK_THREAD_F11_F0(a0)
fsd f12, TASK_THREAD_F12_F0(a0)
fsd f13, TASK_THREAD_F13_F0(a0)
fsd f14, TASK_THREAD_F14_F0(a0)
fsd f15, TASK_THREAD_F15_F0(a0)
fsd f16, TASK_THREAD_F16_F0(a0)
fsd f17, TASK_THREAD_F17_F0(a0)
fsd f18, TASK_THREAD_F18_F0(a0)
fsd f19, TASK_THREAD_F19_F0(a0)
fsd f20, TASK_THREAD_F20_F0(a0)
fsd f21, TASK_THREAD_F21_F0(a0)
fsd f22, TASK_THREAD_F22_F0(a0)
fsd f23, TASK_THREAD_F23_F0(a0)
fsd f24, TASK_THREAD_F24_F0(a0)
fsd f25, TASK_THREAD_F25_F0(a0)
fsd f26, TASK_THREAD_F26_F0(a0)
fsd f27, TASK_THREAD_F27_F0(a0)
fsd f28, TASK_THREAD_F28_F0(a0)
fsd f29, TASK_THREAD_F29_F0(a0)
fsd f30, TASK_THREAD_F30_F0(a0)
fsd f31, TASK_THREAD_F31_F0(a0)
sw t0, TASK_THREAD_FCSR_F0(a0)
csrc sstatus, t1
ret
ENDPROC(__fstate_save)
ENTRY(__fstate_restore)
li a2, TASK_THREAD_F0
add a0, a0, a2
li t1, SR_FS
lw t0, TASK_THREAD_FCSR_F0(a0)
csrs sstatus, t1
fld f0, TASK_THREAD_F0_F0(a0)
fld f1, TASK_THREAD_F1_F0(a0)
fld f2, TASK_THREAD_F2_F0(a0)
fld f3, TASK_THREAD_F3_F0(a0)
fld f4, TASK_THREAD_F4_F0(a0)
fld f5, TASK_THREAD_F5_F0(a0)
fld f6, TASK_THREAD_F6_F0(a0)
fld f7, TASK_THREAD_F7_F0(a0)
fld f8, TASK_THREAD_F8_F0(a0)
fld f9, TASK_THREAD_F9_F0(a0)
fld f10, TASK_THREAD_F10_F0(a0)
fld f11, TASK_THREAD_F11_F0(a0)
fld f12, TASK_THREAD_F12_F0(a0)
fld f13, TASK_THREAD_F13_F0(a0)
fld f14, TASK_THREAD_F14_F0(a0)
fld f15, TASK_THREAD_F15_F0(a0)
fld f16, TASK_THREAD_F16_F0(a0)
fld f17, TASK_THREAD_F17_F0(a0)
fld f18, TASK_THREAD_F18_F0(a0)
fld f19, TASK_THREAD_F19_F0(a0)
fld f20, TASK_THREAD_F20_F0(a0)
fld f21, TASK_THREAD_F21_F0(a0)
fld f22, TASK_THREAD_F22_F0(a0)
fld f23, TASK_THREAD_F23_F0(a0)
fld f24, TASK_THREAD_F24_F0(a0)
fld f25, TASK_THREAD_F25_F0(a0)
fld f26, TASK_THREAD_F26_F0(a0)
fld f27, TASK_THREAD_F27_F0(a0)
fld f28, TASK_THREAD_F28_F0(a0)
fld f29, TASK_THREAD_F29_F0(a0)
fld f30, TASK_THREAD_F30_F0(a0)
fld f31, TASK_THREAD_F31_F0(a0)
fscsr t0
csrc sstatus, t1
ret
ENDPROC(__fstate_restore)
.section ".rodata"
/* Exception vector table */
ENTRY(excp_vect_table)

106
arch/riscv/kernel/fpu.S Normal file
Vedi File

@@ -0,0 +1,106 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2012 Regents of the University of California
* Copyright (C) 2017 SiFive
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/linkage.h>
#include <asm/asm.h>
#include <asm/csr.h>
#include <asm/asm-offsets.h>
ENTRY(__fstate_save)
li a2, TASK_THREAD_F0
add a0, a0, a2
li t1, SR_FS
csrs sstatus, t1
frcsr t0
fsd f0, TASK_THREAD_F0_F0(a0)
fsd f1, TASK_THREAD_F1_F0(a0)
fsd f2, TASK_THREAD_F2_F0(a0)
fsd f3, TASK_THREAD_F3_F0(a0)
fsd f4, TASK_THREAD_F4_F0(a0)
fsd f5, TASK_THREAD_F5_F0(a0)
fsd f6, TASK_THREAD_F6_F0(a0)
fsd f7, TASK_THREAD_F7_F0(a0)
fsd f8, TASK_THREAD_F8_F0(a0)
fsd f9, TASK_THREAD_F9_F0(a0)
fsd f10, TASK_THREAD_F10_F0(a0)
fsd f11, TASK_THREAD_F11_F0(a0)
fsd f12, TASK_THREAD_F12_F0(a0)
fsd f13, TASK_THREAD_F13_F0(a0)
fsd f14, TASK_THREAD_F14_F0(a0)
fsd f15, TASK_THREAD_F15_F0(a0)
fsd f16, TASK_THREAD_F16_F0(a0)
fsd f17, TASK_THREAD_F17_F0(a0)
fsd f18, TASK_THREAD_F18_F0(a0)
fsd f19, TASK_THREAD_F19_F0(a0)
fsd f20, TASK_THREAD_F20_F0(a0)
fsd f21, TASK_THREAD_F21_F0(a0)
fsd f22, TASK_THREAD_F22_F0(a0)
fsd f23, TASK_THREAD_F23_F0(a0)
fsd f24, TASK_THREAD_F24_F0(a0)
fsd f25, TASK_THREAD_F25_F0(a0)
fsd f26, TASK_THREAD_F26_F0(a0)
fsd f27, TASK_THREAD_F27_F0(a0)
fsd f28, TASK_THREAD_F28_F0(a0)
fsd f29, TASK_THREAD_F29_F0(a0)
fsd f30, TASK_THREAD_F30_F0(a0)
fsd f31, TASK_THREAD_F31_F0(a0)
sw t0, TASK_THREAD_FCSR_F0(a0)
csrc sstatus, t1
ret
ENDPROC(__fstate_save)
ENTRY(__fstate_restore)
li a2, TASK_THREAD_F0
add a0, a0, a2
li t1, SR_FS
lw t0, TASK_THREAD_FCSR_F0(a0)
csrs sstatus, t1
fld f0, TASK_THREAD_F0_F0(a0)
fld f1, TASK_THREAD_F1_F0(a0)
fld f2, TASK_THREAD_F2_F0(a0)
fld f3, TASK_THREAD_F3_F0(a0)
fld f4, TASK_THREAD_F4_F0(a0)
fld f5, TASK_THREAD_F5_F0(a0)
fld f6, TASK_THREAD_F6_F0(a0)
fld f7, TASK_THREAD_F7_F0(a0)
fld f8, TASK_THREAD_F8_F0(a0)
fld f9, TASK_THREAD_F9_F0(a0)
fld f10, TASK_THREAD_F10_F0(a0)
fld f11, TASK_THREAD_F11_F0(a0)
fld f12, TASK_THREAD_F12_F0(a0)
fld f13, TASK_THREAD_F13_F0(a0)
fld f14, TASK_THREAD_F14_F0(a0)
fld f15, TASK_THREAD_F15_F0(a0)
fld f16, TASK_THREAD_F16_F0(a0)
fld f17, TASK_THREAD_F17_F0(a0)
fld f18, TASK_THREAD_F18_F0(a0)
fld f19, TASK_THREAD_F19_F0(a0)
fld f20, TASK_THREAD_F20_F0(a0)
fld f21, TASK_THREAD_F21_F0(a0)
fld f22, TASK_THREAD_F22_F0(a0)
fld f23, TASK_THREAD_F23_F0(a0)
fld f24, TASK_THREAD_F24_F0(a0)
fld f25, TASK_THREAD_F25_F0(a0)
fld f26, TASK_THREAD_F26_F0(a0)
fld f27, TASK_THREAD_F27_F0(a0)
fld f28, TASK_THREAD_F28_F0(a0)
fld f29, TASK_THREAD_F29_F0(a0)
fld f30, TASK_THREAD_F30_F0(a0)
fld f31, TASK_THREAD_F31_F0(a0)
fscsr t0
csrc sstatus, t1
ret
ENDPROC(__fstate_restore)

6
arch/riscv/kernel/process.c
Vedi File

@@ -76,7 +76,9 @@ void show_regs(struct pt_regs *regs)
void start_thread(struct pt_regs *regs, unsigned long pc,
unsigned long sp)
{
regs->sstatus = SR_SPIE /* User mode, irqs on */ | SR_FS_INITIAL;
regs->sstatus = SR_SPIE;
if (has_fpu)
regs->sstatus |= SR_FS_INITIAL;
regs->sepc = pc;
regs->sp = sp;
set_fs(USER_DS);
@@ -84,12 +86,14 @@ void start_thread(struct pt_regs *regs, unsigned long pc,
void flush_thread(void)
{
#ifdef CONFIG_FPU
/*
* Reset FPU context
* frm: round to nearest, ties to even (IEEE default)
* fflags: accrued exceptions cleared
*/
memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
#endif
}
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)

85
arch/riscv/kernel/signal.c
Vedi File

@@ -37,45 +37,69 @@ struct rt_sigframe {
struct ucontext uc;
};
static long restore_d_state(struct pt_regs *regs,
struct __riscv_d_ext_state __user *state)
{
long err;
err = __copy_from_user(&current->thread.fstate, state, sizeof(*state));
if (likely(!err))
fstate_restore(current, regs);
return err;
}
static long save_d_state(struct pt_regs *regs,
struct __riscv_d_ext_state __user *state)
{
fstate_save(current, regs);
return __copy_to_user(state, &current->thread.fstate, sizeof(*state));
}
static long restore_sigcontext(struct pt_regs *regs,
struct sigcontext __user *sc)
#ifdef CONFIG_FPU
static long restore_fp_state(struct pt_regs *regs,
union __riscv_fp_state *sc_fpregs)
{
long err;
struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
size_t i;
/* sc_regs is structured the same as the start of pt_regs */
err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs));
if (unlikely(err))
return err;
/* Restore the floating-point state. */
err = restore_d_state(regs, &sc->sc_fpregs.d);
err = __copy_from_user(&current->thread.fstate, state, sizeof(*state));
if (unlikely(err))
return err;
fstate_restore(current, regs);
/* We support no other extension state at this time. */
for (i = 0; i < ARRAY_SIZE(sc->sc_fpregs.q.reserved); i++) {
for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
u32 value;
err = __get_user(value, &sc->sc_fpregs.q.reserved[i]);
err = __get_user(value, &sc_fpregs->q.reserved[i]);
if (unlikely(err))
break;
if (value != 0)
return -EINVAL;
}
return err;
}
static long save_fp_state(struct pt_regs *regs,
union __riscv_fp_state *sc_fpregs)
{
long err;
struct __riscv_d_ext_state __user *state = &sc_fpregs->d;
size_t i;
fstate_save(current, regs);
err = __copy_to_user(state, &current->thread.fstate, sizeof(*state));
if (unlikely(err))
return err;
/* We support no other extension state at this time. */
for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) {
err = __put_user(0, &sc_fpregs->q.reserved[i]);
if (unlikely(err))
break;
}
return err;
}
#else
#define save_fp_state(task, regs) (0)
#define restore_fp_state(task, regs) (0)
#endif
static long restore_sigcontext(struct pt_regs *regs,
struct sigcontext __user *sc)
{
long err;
/* sc_regs is structured the same as the start of pt_regs */
err = __copy_from_user(regs, &sc->sc_regs, sizeof(sc->sc_regs));
/* Restore the floating-point state. */
if (has_fpu)
err |= restore_fp_state(regs, &sc->sc_fpregs);
return err;
}
@@ -124,14 +148,11 @@ static long setup_sigcontext(struct rt_sigframe __user *frame,
{
struct sigcontext __user *sc = &frame->uc.uc_mcontext;
long err;
size_t i;
/* sc_regs is structured the same as the start of pt_regs */
err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs));
/* Save the floating-point state. */
err |= save_d_state(regs, &sc->sc_fpregs.d);
/* We support no other extension state at this time. */
for (i = 0; i < ARRAY_SIZE(sc->sc_fpregs.q.reserved); i++)
err |= __put_user(0, &sc->sc_fpregs.q.reserved[i]);
if (has_fpu)
err |= save_fp_state(regs, &sc->sc_fpregs);
return err;
}