[PATCH 11/16] MIPS: save MSA extended context around signals
From: Paul Burton
Date: Fri Jul 10 2015 - 11:04:24 EST
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.
Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
---
arch/mips/kernel/r4k_fpu.S | 119 ++++++++++++++++++
arch/mips/kernel/signal-common.h | 3 +
arch/mips/kernel/signal.c | 252 ++++++++++++++++++++++++++++++++++-----
3 files changed, 344 insertions(+), 30 deletions(-)
diff --git a/arch/mips/kernel/r4k_fpu.S b/arch/mips/kernel/r4k_fpu.S
index aa11f43..c7fe72d 100644
--- a/arch/mips/kernel/r4k_fpu.S
+++ b/arch/mips/kernel/r4k_fpu.S
@@ -13,6 +13,7 @@
* Copyright (C) 1999, 2001 Silicon Graphics, Inc.
*/
#include <asm/asm.h>
+#include <asm/asmmacro.h>
#include <asm/errno.h>
#include <asm/fpregdef.h>
#include <asm/mipsregs.h>
@@ -171,6 +172,124 @@ LEAF(_restore_fp_context)
li v0, 0 # success
END(_restore_fp_context)
+#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
.type fault@function
diff --git a/arch/mips/kernel/signal-common.h b/arch/mips/kernel/signal-common.h
index d594695..a99987f 100644
--- a/arch/mips/kernel/signal-common.h
+++ b/arch/mips/kernel/signal-common.h
@@ -42,4 +42,7 @@ _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 4e626ca..98bbca6 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -38,6 +38,7 @@
#include <asm/vdso.h>
#include <asm/dsp.h>
#include <asm/inst.h>
+#include <asm/msa.h>
#include "signal-common.h"
@@ -125,6 +126,168 @@ static int restore_hw_fp_context(void __user *sc)
}
/*
+ * 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
*/
int protected_save_fp_context(void __user *sc)
@@ -133,7 +296,7 @@ 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;
@@ -142,39 +305,40 @@ int protected_save_fp_context(void __user *sc)
used |= USED_FR1;
if (test_thread_flag(TIF_HYBRID_FPREGS))
used |= USED_HYBRID_FPRS;
- }
- err = __put_user(used, used_math);
- if (err || !(used & USED_FP))
- return err;
-
- /*
- * EVA does not have userland equivalents of ldc1 or sdc1, so
- * save to the kernel FP context & copy that to userland below.
- */
- if (config_enabled(CONFIG_EVA))
- lose_fpu(1);
-
- while (1) {
- lock_fpu_owner();
- if (is_fpu_owner()) {
- err = save_fp_context(sc);
- unlock_fpu_owner();
- } else {
- unlock_fpu_owner();
- err = copy_fp_to_sigcontext(sc);
+ /*
+ * EVA does not have userland equivalents of ldc1 or sdc1, so
+ * save to the kernel FP context & copy that to userland below.
+ */
+ if (config_enabled(CONFIG_EVA))
+ lose_fpu(1);
+
+ while (1) {
+ lock_fpu_owner();
+ if (is_fpu_owner()) {
+ err = save_fp_context(sc);
+ unlock_fpu_owner();
+ } else {
+ unlock_fpu_owner();
+ err = copy_fp_to_sigcontext(sc);
+ }
+ if (likely(!err))
+ break;
+ /* touch the sigcontext and try again */
+ err = __put_user(0, &fpregs[0]) |
+ __put_user(0, &fpregs[31]) |
+ __put_user(0, csr);
+ if (err)
+ return err; /* really bad sigcontext */
}
- if (likely(!err))
- break;
- /* touch the sigcontext and try again */
- err = __put_user(0, &fpregs[0]) |
- __put_user(0, &fpregs[31]) |
- __put_user(0, csr);
- if (err)
- break; /* really bad sigcontext */
}
- return err;
+ 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)
@@ -229,6 +393,9 @@ int protected_restore_fp_context(void __user *sc)
break; /* really bad sigcontext */
}
+ if (used & USED_EXTCONTEXT)
+ err |= restore_extcontext(sc_to_extcontext(sc));
+
return err ?: sig;
}
@@ -268,6 +435,28 @@ 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 +513,9 @@ 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];
--
2.4.4
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