From bf82cb30c7e58b3a9742f0a45962ebdf51befac7 Mon Sep 17 00:00:00 2001 From: Paul Burton Date: Mon, 27 Jul 2015 12:58:22 -0700 Subject: [PATCH] MIPS: Save MSA extended context around signals It is desirable for signal handlers to be allowed to make use of MSA, particularly if auto vectorisation is used when compiling a program. The MSA context must therefore be saved & restored before & after invoking the signal handler. Make use of the extended context structs defined in the preceding patch to save MSA context after the sigframe when appropriate. [ralf@linux-mips.org: Fixed conflicts.] Signed-off-by: Paul Burton Cc: linux-mips@linux-mips.org Cc: Guenter Roeck Cc: Matthew Fortune Cc: Leonid Yegoshin Cc: linux-kernel@vger.kernel.org Cc: Richard Weinberger Cc: James Hogan Cc: Andrew Morton Cc: Andy Lutomirski Cc: Markos Chandras Cc: Manuel Lauss Cc: Maciej W. Rozycki Patchwork: https://patchwork.linux-mips.org/patch/10796/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/r4k_fpu.S | 118 ++++++++++++++++ arch/mips/kernel/signal-common.h | 3 + arch/mips/kernel/signal.c | 227 +++++++++++++++++++++++++++++-- 3 files changed, 333 insertions(+), 15 deletions(-) diff --git a/arch/mips/kernel/r4k_fpu.S b/arch/mips/kernel/r4k_fpu.S index 0ed139889245..f09546ee2cdc 100644 --- a/arch/mips/kernel/r4k_fpu.S +++ b/arch/mips/kernel/r4k_fpu.S @@ -236,6 +236,124 @@ LEAF(\name) op_msa_wr write_msa_wr_w, ld_w op_msa_wr write_msa_wr_d, ld_d +#endif /* CONFIG_CPU_HAS_MSA */ + +#ifdef CONFIG_CPU_HAS_MSA + + .macro save_msa_upper wr, off, base + .set push + .set noat +#ifdef CONFIG_64BIT + copy_u_d \wr, 1 + EX sd $1, \off(\base) +#elif defined(CONFIG_CPU_LITTLE_ENDIAN) + copy_u_w \wr, 2 + EX sw $1, \off(\base) + copy_u_w \wr, 3 + EX sw $1, (\off+4)(\base) +#else /* CONFIG_CPU_BIG_ENDIAN */ + copy_u_w \wr, 2 + EX sw $1, (\off+4)(\base) + copy_u_w \wr, 3 + EX sw $1, \off(\base) +#endif + .set pop + .endm + +LEAF(_save_msa_all_upper) + save_msa_upper 0, 0x00, a0 + save_msa_upper 1, 0x08, a0 + save_msa_upper 2, 0x10, a0 + save_msa_upper 3, 0x18, a0 + save_msa_upper 4, 0x20, a0 + save_msa_upper 5, 0x28, a0 + save_msa_upper 6, 0x30, a0 + save_msa_upper 7, 0x38, a0 + save_msa_upper 8, 0x40, a0 + save_msa_upper 9, 0x48, a0 + save_msa_upper 10, 0x50, a0 + save_msa_upper 11, 0x58, a0 + save_msa_upper 12, 0x60, a0 + save_msa_upper 13, 0x68, a0 + save_msa_upper 14, 0x70, a0 + save_msa_upper 15, 0x78, a0 + save_msa_upper 16, 0x80, a0 + save_msa_upper 17, 0x88, a0 + save_msa_upper 18, 0x90, a0 + save_msa_upper 19, 0x98, a0 + save_msa_upper 20, 0xa0, a0 + save_msa_upper 21, 0xa8, a0 + save_msa_upper 22, 0xb0, a0 + save_msa_upper 23, 0xb8, a0 + save_msa_upper 24, 0xc0, a0 + save_msa_upper 25, 0xc8, a0 + save_msa_upper 26, 0xd0, a0 + save_msa_upper 27, 0xd8, a0 + save_msa_upper 28, 0xe0, a0 + save_msa_upper 29, 0xe8, a0 + save_msa_upper 30, 0xf0, a0 + save_msa_upper 31, 0xf8, a0 + jr ra + li v0, 0 + END(_save_msa_all_upper) + + .macro restore_msa_upper wr, off, base + .set push + .set noat +#ifdef CONFIG_64BIT + EX ld $1, \off(\base) + insert_d \wr, 1 +#elif defined(CONFIG_CPU_LITTLE_ENDIAN) + EX lw $1, \off(\base) + insert_w \wr, 2 + EX lw $1, (\off+4)(\base) + insert_w \wr, 3 +#else /* CONFIG_CPU_BIG_ENDIAN */ + EX lw $1, (\off+4)(\base) + insert_w \wr, 2 + EX lw $1, \off(\base) + insert_w \wr, 3 +#endif + .set pop + .endm + +LEAF(_restore_msa_all_upper) + restore_msa_upper 0, 0x00, a0 + restore_msa_upper 1, 0x08, a0 + restore_msa_upper 2, 0x10, a0 + restore_msa_upper 3, 0x18, a0 + restore_msa_upper 4, 0x20, a0 + restore_msa_upper 5, 0x28, a0 + restore_msa_upper 6, 0x30, a0 + restore_msa_upper 7, 0x38, a0 + restore_msa_upper 8, 0x40, a0 + restore_msa_upper 9, 0x48, a0 + restore_msa_upper 10, 0x50, a0 + restore_msa_upper 11, 0x58, a0 + restore_msa_upper 12, 0x60, a0 + restore_msa_upper 13, 0x68, a0 + restore_msa_upper 14, 0x70, a0 + restore_msa_upper 15, 0x78, a0 + restore_msa_upper 16, 0x80, a0 + restore_msa_upper 17, 0x88, a0 + restore_msa_upper 18, 0x90, a0 + restore_msa_upper 19, 0x98, a0 + restore_msa_upper 20, 0xa0, a0 + restore_msa_upper 21, 0xa8, a0 + restore_msa_upper 22, 0xb0, a0 + restore_msa_upper 23, 0xb8, a0 + restore_msa_upper 24, 0xc0, a0 + restore_msa_upper 25, 0xc8, a0 + restore_msa_upper 26, 0xd0, a0 + restore_msa_upper 27, 0xd8, a0 + restore_msa_upper 28, 0xe0, a0 + restore_msa_upper 29, 0xe8, a0 + restore_msa_upper 30, 0xf0, a0 + restore_msa_upper 31, 0xf8, a0 + jr ra + li v0, 0 + END(_restore_msa_all_upper) + #endif /* CONFIG_CPU_HAS_MSA */ .set reorder diff --git a/arch/mips/kernel/signal-common.h b/arch/mips/kernel/signal-common.h index 96b0fd82f8b5..f50d48435c68 100644 --- a/arch/mips/kernel/signal-common.h +++ b/arch/mips/kernel/signal-common.h @@ -37,4 +37,7 @@ _save_fp_context(void __user *fpregs, void __user *csr); extern asmlinkage int _restore_fp_context(void __user *fpregs, void __user *csr); +extern asmlinkage int _save_msa_all_upper(void __user *buf); +extern asmlinkage int _restore_msa_all_upper(void __user *buf); + #endif /* __SIGNAL_COMMON_H */ diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c index 3101bafd3a9c..fa13a52713df 100644 --- a/arch/mips/kernel/signal.c +++ b/arch/mips/kernel/signal.c @@ -38,6 +38,7 @@ #include #include #include +#include #include "signal-common.h" @@ -124,6 +125,168 @@ static int restore_hw_fp_context(void __user *sc) return _restore_fp_context(fpregs, csr); } +/* + * Extended context handling. + */ + +static inline void __user *sc_to_extcontext(void __user *sc) +{ + struct ucontext __user *uc; + + /* + * We can just pretend the sigcontext is always embedded in a struct + * ucontext here, because the offset from sigcontext to extended + * context is the same in the struct sigframe case. + */ + uc = container_of(sc, struct ucontext, uc_mcontext); + return &uc->uc_extcontext; +} + +static int save_msa_extcontext(void __user *buf) +{ + struct msa_extcontext __user *msa = buf; + uint64_t val; + int i, err; + + if (!thread_msa_context_live()) + return 0; + + /* + * Ensure that we can't lose the live MSA context between checking + * for it & writing it to memory. + */ + preempt_disable(); + + if (is_msa_enabled()) { + /* + * There are no EVA versions of the vector register load/store + * instructions, so MSA context has to be saved to kernel memory + * and then copied to user memory. The save to kernel memory + * should already have been done when handling scalar FP + * context. + */ + BUG_ON(config_enabled(CONFIG_EVA)); + + err = __put_user(read_msa_csr(), &msa->csr); + err |= _save_msa_all_upper(&msa->wr); + + preempt_enable(); + } else { + preempt_enable(); + + err = __put_user(current->thread.fpu.msacsr, &msa->csr); + + for (i = 0; i < NUM_FPU_REGS; i++) { + val = get_fpr64(¤t->thread.fpu.fpr[i], 1); + err |= __put_user(val, &msa->wr[i]); + } + } + + err |= __put_user(MSA_EXTCONTEXT_MAGIC, &msa->ext.magic); + err |= __put_user(sizeof(*msa), &msa->ext.size); + + return err ? -EFAULT : sizeof(*msa); +} + +static int restore_msa_extcontext(void __user *buf, unsigned int size) +{ + struct msa_extcontext __user *msa = buf; + unsigned long long val; + unsigned int csr; + int i, err; + + if (size != sizeof(*msa)) + return -EINVAL; + + err = get_user(csr, &msa->csr); + if (err) + return err; + + preempt_disable(); + + if (is_msa_enabled()) { + /* + * There are no EVA versions of the vector register load/store + * instructions, so MSA context has to be copied to kernel + * memory and later loaded to registers. The same is true of + * scalar FP context, so FPU & MSA should have already been + * disabled whilst handling scalar FP context. + */ + BUG_ON(config_enabled(CONFIG_EVA)); + + write_msa_csr(csr); + err |= _restore_msa_all_upper(&msa->wr); + preempt_enable(); + } else { + preempt_enable(); + + current->thread.fpu.msacsr = csr; + + for (i = 0; i < NUM_FPU_REGS; i++) { + err |= __get_user(val, &msa->wr[i]); + set_fpr64(¤t->thread.fpu.fpr[i], 1, val); + } + } + + return err; +} + +static int save_extcontext(void __user *buf) +{ + int sz; + + sz = save_msa_extcontext(buf); + if (sz < 0) + return sz; + buf += sz; + + /* If no context was saved then trivially return */ + if (!sz) + return 0; + + /* Write the end marker */ + if (__put_user(END_EXTCONTEXT_MAGIC, (u32 *)buf)) + return -EFAULT; + + sz += sizeof(((struct extcontext *)NULL)->magic); + return sz; +} + +static int restore_extcontext(void __user *buf) +{ + struct extcontext ext; + int err; + + while (1) { + err = __get_user(ext.magic, (unsigned int *)buf); + if (err) + return err; + + if (ext.magic == END_EXTCONTEXT_MAGIC) + return 0; + + err = __get_user(ext.size, (unsigned int *)(buf + + offsetof(struct extcontext, size))); + if (err) + return err; + + switch (ext.magic) { + case MSA_EXTCONTEXT_MAGIC: + err = restore_msa_extcontext(buf, ext.size); + break; + + default: + err = -EINVAL; + break; + } + + if (err) + return err; + + buf += ext.size; + } +} + /* * Helper routines */ @@ -133,20 +296,17 @@ int protected_save_fp_context(void __user *sc) uint64_t __user *fpregs = sc + abi->off_sc_fpregs; uint32_t __user *csr = sc + abi->off_sc_fpc_csr; uint32_t __user *used_math = sc + abi->off_sc_used_math; - unsigned int used; + unsigned int used, ext_sz; int err; used = used_math() ? USED_FP : 0; - if (used) { - if (!test_thread_flag(TIF_32BIT_FPREGS)) - used |= USED_FR1; - if (test_thread_flag(TIF_HYBRID_FPREGS)) - used |= USED_HYBRID_FPRS; - } + if (!used) + goto fp_done; - err = __put_user(used, used_math); - if (err || !(used & USED_FP)) - return err; + if (!test_thread_flag(TIF_32BIT_FPREGS)) + used |= USED_FR1; + if (test_thread_flag(TIF_HYBRID_FPREGS)) + used |= USED_HYBRID_FPRS; /* * EVA does not have userland equivalents of ldc1 or sdc1, so @@ -171,10 +331,16 @@ int protected_save_fp_context(void __user *sc) __put_user(0, &fpregs[31]) | __put_user(0, csr); if (err) - break; /* really bad sigcontext */ + return err; /* really bad sigcontext */ } - return err; +fp_done: + ext_sz = err = save_extcontext(sc_to_extcontext(sc)); + if (err < 0) + return err; + used |= ext_sz ? USED_EXTCONTEXT : 0; + + return __put_user(used, used_math); } int protected_restore_fp_context(void __user *sc) @@ -184,7 +350,7 @@ int protected_restore_fp_context(void __user *sc) uint32_t __user *csr = sc + abi->off_sc_fpc_csr; uint32_t __user *used_math = sc + abi->off_sc_used_math; unsigned int used; - int err, sig, tmp __maybe_unused; + int err, sig = 0, tmp __maybe_unused; err = __get_user(used, used_math); conditional_used_math(used & USED_FP); @@ -193,10 +359,12 @@ int protected_restore_fp_context(void __user *sc) * The signal handler may have used FPU; give it up if the program * doesn't want it following sigreturn. */ - if (err || !(used & USED_FP)) { + if (err || !(used & USED_FP)) lose_fpu(0); + if (err) return err; - } + if (!(used & USED_FP)) + goto fp_done; err = sig = fpcsr_pending(csr); if (err < 0) @@ -229,6 +397,10 @@ int protected_restore_fp_context(void __user *sc) break; /* really bad sigcontext */ } +fp_done: + if (used & USED_EXTCONTEXT) + err |= restore_extcontext(sc_to_extcontext(sc)); + return err ?: sig; } @@ -268,6 +440,28 @@ int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) return err; } +static size_t extcontext_max_size(void) +{ + size_t sz = 0; + + /* + * The assumption here is that between this point & the point at which + * the extended context is saved the size of the context should only + * ever be able to shrink (if the task is preempted), but never grow. + * That is, what this function returns is an upper bound on the size of + * the extended context for the current task at the current time. + */ + + if (thread_msa_context_live()) + sz += sizeof(struct msa_extcontext); + + /* If any context is saved then we'll append the end marker */ + if (sz) + sz += sizeof(((struct extcontext *)NULL)->magic); + + return sz; +} + int fpcsr_pending(unsigned int __user *fpcsr) { int err, sig = 0; @@ -324,6 +518,9 @@ void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, { unsigned long sp; + /* Leave space for potential extended context */ + frame_size += extcontext_max_size(); + /* Default to using normal stack */ sp = regs->regs[29]; -- 2.34.1