[v3,5/5] aarch64-linux-user: Add support for SVE signal frame records

Message ID 20180216215608.13227-6-richard.henderson@linaro.org
State New
Headers show
Series
  • target/arm: linux-user changes for sve
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Commit Message

Richard Henderson Feb. 16, 2018, 9:56 p.m.
Depending on the currently selected size of the SVE vector registers,
we can either store the data within the "standard" allocation, or we
may beedn to allocate additional space with an EXTRA record.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

---
 linux-user/signal.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 138 insertions(+), 3 deletions(-)

-- 
2.14.3

Comments

Peter Maydell Feb. 22, 2018, 4:41 p.m. | #1
On 16 February 2018 at 21:56, Richard Henderson
<richard.henderson@linaro.org> wrote:
> Depending on the currently selected size of the SVE vector registers,

> we can either store the data within the "standard" allocation, or we

> may beedn to allocate additional space with an EXTRA record.

>

> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

> ---

>  linux-user/signal.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++++++--

>  1 file changed, 138 insertions(+), 3 deletions(-)

>

> diff --git a/linux-user/signal.c b/linux-user/signal.c

> index ca0ba28c98..4c9fef4bb2 100644

> --- a/linux-user/signal.c

> +++ b/linux-user/signal.c

> @@ -1452,6 +1452,30 @@ struct target_extra_context {

>      uint32_t reserved[3];

>  };

>

> +#define TARGET_SVE_MAGIC    0x53564501

> +

> +struct target_sve_context {

> +    struct target_aarch64_ctx head;

> +    uint16_t vl;

> +    uint16_t reserved[3];


Worth commenting that actual SVE register data will directly follow the struct.


> +static void target_restore_sve_record(CPUARMState *env,

> +                                      struct target_sve_context *sve, int vq)

> +{

> +    int i, j;

> +

> +    /* Note that SVE regs are stored as a byte stream, with each byte element

> +     * at a subsequent address.  This corresponds to a little-endian store

> +     * of our 64-bit hunks.


We're doing loads in this function, not stores.

> +     */

> +    for (i = 0; i < 32; ++i) {

> +        uint64_t *z = (void *)sve + TARGET_SVE_SIG_ZREG_OFFSET(vq, i);

> +        for (j = 0; j < vq * 2; ++j) {

> +            __get_user_e(env->vfp.zregs[i].d[j], z + j, le);

> +        }

> +    }

> +    for (i = 0; i <= 16; ++i) {

> +        uint16_t *p = (void *)sve + TARGET_SVE_SIG_PREG_OFFSET(vq, i);

> +        for (j = 0; j < vq; ++j) {

> +            uint16_t r;

> +            __get_user_e(r, p + j, le);

> +            if (j & 3) {

> +                env->vfp.pregs[i].p[j >> 2] |= (uint64_t)r << ((j & 3) * 16);

> +            } else {

> +                env->vfp.pregs[i].p[j >> 2] = r;

> +            }

> +        }

> +    }

> +}

> +


> @@ -1659,21 +1759,53 @@ static void target_setup_frame(int usig, struct target_sigaction *ka,

>                                 target_siginfo_t *info, target_sigset_t *set,

>                                 CPUARMState *env)

>  {

> +    int std_size = sizeof(struct target_rt_sigframe);

>      int size = offsetof(struct target_rt_sigframe, uc.tuc_mcontext.__reserved);

>      int fpsimd_ofs, end1_ofs, fr_ofs, end2_ofs = 0;

>      int extra_ofs = 0, extra_base = 0, extra_size = 0;

> +    int sve_ofs = 0, vq = 0, sve_size = 0;

>      struct target_rt_sigframe *frame;

>      struct target_rt_frame_record *fr;

>      abi_ulong frame_addr, return_addr;

>

> +    /* Reserve space for standard exit marker.  */

> +    std_size -= sizeof(struct target_aarch64_ctx);

> +

> +    /* FPSIMD record is always in the standard space.  */

>      fpsimd_ofs = size;

>      size += sizeof(struct target_fpsimd_context);

>      end1_ofs = size;

> +

> +    /* SVE state needs saving only if it exists.  */

> +    if (arm_feature(env, ARM_FEATURE_SVE)) {

> +        vq = (env->vfp.zcr_el[1] & 0xf) + 1;

> +        sve_size = QEMU_ALIGN_UP(TARGET_SVE_SIG_CONTEXT_SIZE(vq), 16);

> +

> +        /* For VQ <= 6, there is room in the standard space.  */


The kernel header arch/arm64/include/uapi/asm/sigcontext.h
claims the record is in the standard space if "vl <= 64", which
doesn't seem to match up with "VQ <= 6" ?

> +        if (sve_size <= std_size) {

> +            sve_ofs = size;

> +            size += sve_size;

> +            end1_ofs = size;

> +        } else {

> +            /* Otherwise we need to allocate extra space.  */

> +            extra_ofs = size;

> +            size += sizeof(struct target_extra_context);

> +            end1_ofs = size;

> +            size += QEMU_ALIGN_UP(sizeof(struct target_aarch64_ctx), 16);


Why do we add the size of target_aarch64_ctx to size here?
We already account for the size of the end record later, so
what is this one?

> +            extra_base = size;

> +            extra_size = sve_size + sizeof(struct target_aarch64_ctx);


If we ever get two different kinds of optional record that need to
live in the extra space, this is going to need refactoring,
because at the moment it assumes that the SVE record is the first
and only thing that might live there. I guess that's OK for now, though.

> +

> +            sve_ofs = size;

> +            size += sve_size;

> +            end2_ofs = size;

> +        }

> +    }

>      size += sizeof(struct target_aarch64_ctx);

> +

>      fr_ofs = size;

>      size += sizeof(struct target_rt_frame_record);

>

> -    frame_addr = get_sigframe(ka, env);

> +    frame_addr = get_sigframe(ka, env, size);

>      trace_user_setup_frame(env, frame_addr);

>      if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {

>          goto give_sigsegv;

> @@ -1686,6 +1818,9 @@ static void target_setup_frame(int usig, struct target_sigaction *ka,

>                                    frame_addr + extra_base, extra_size);

>      }

>      target_setup_end_record((void *)frame + end1_ofs);

> +    if (sve_ofs) {

> +        target_setup_sve_record((void *)frame + sve_ofs, env, vq, sve_size);

> +    }

>      if (end2_ofs) {

>          target_setup_end_record((void *)frame + end2_ofs);

>      }

> --


thanks
-- PMM
Richard Henderson Feb. 22, 2018, 8:14 p.m. | #2
On 02/22/2018 08:41 AM, Peter Maydell wrote:
> On 16 February 2018 at 21:56, Richard Henderson

> <richard.henderson@linaro.org> wrote:

>> Depending on the currently selected size of the SVE vector registers,

>> we can either store the data within the "standard" allocation, or we

>> may beedn to allocate additional space with an EXTRA record.

>>

>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

>> ---

>>  linux-user/signal.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++++++--

>>  1 file changed, 138 insertions(+), 3 deletions(-)

>>

>> diff --git a/linux-user/signal.c b/linux-user/signal.c

>> index ca0ba28c98..4c9fef4bb2 100644

>> --- a/linux-user/signal.c

>> +++ b/linux-user/signal.c

>> @@ -1452,6 +1452,30 @@ struct target_extra_context {

>>      uint32_t reserved[3];

>>  };

>>

>> +#define TARGET_SVE_MAGIC    0x53564501

>> +

>> +struct target_sve_context {

>> +    struct target_aarch64_ctx head;

>> +    uint16_t vl;

>> +    uint16_t reserved[3];

> 

> Worth commenting that actual SVE register data will directly follow the struct.


Sure.

>> +static void target_restore_sve_record(CPUARMState *env,

>> +                                      struct target_sve_context *sve, int vq)

>> +{

>> +    int i, j;

>> +

>> +    /* Note that SVE regs are stored as a byte stream, with each byte element

>> +     * at a subsequent address.  This corresponds to a little-endian store

>> +     * of our 64-bit hunks.

> 

> We're doing loads in this function, not stores.


Oops.

>> +    /* SVE state needs saving only if it exists.  */

>> +    if (arm_feature(env, ARM_FEATURE_SVE)) {

>> +        vq = (env->vfp.zcr_el[1] & 0xf) + 1;

>> +        sve_size = QEMU_ALIGN_UP(TARGET_SVE_SIG_CONTEXT_SIZE(vq), 16);

>> +

>> +        /* For VQ <= 6, there is room in the standard space.  */

> 

> The kernel header arch/arm64/include/uapi/asm/sigcontext.h

> claims the record is in the standard space if "vl <= 64", which

> doesn't seem to match up with "VQ <= 6" ?


*shrug* I suppose the kernel guys only considered sizes that are powers of two,
even though other sizes are clearly allowed by the implementation?

The 4096 reserved bytes - sizeof(fpsimd) - sizeof(end) = 3560 bytes.
Values for TARGET_SVE_SIG_CONTEXT_SIZE(vq) are:
1	562
2	1108
3	1654
4	2200
5	2746
6	3292
7	3838
8	4384

So there's definitely room for VQ=6, with 268 bytes left over.

> 

>> +        if (sve_size <= std_size) {

>> +            sve_ofs = size;

>> +            size += sve_size;

>> +            end1_ofs = size;

>> +        } else {

>> +            /* Otherwise we need to allocate extra space.  */

>> +            extra_ofs = size;

>> +            size += sizeof(struct target_extra_context);

>> +            end1_ofs = size;

>> +            size += QEMU_ALIGN_UP(sizeof(struct target_aarch64_ctx), 16);

> 

> Why do we add the size of target_aarch64_ctx to size here?

> We already account for the size of the end record later, so

> what is this one?


This is for the end record within the extra space, as opposed to the end record
within the standard space which is what we accounted for before.  A comment
would help, I supposed.

> 

>> +            extra_base = size;

>> +            extra_size = sve_size + sizeof(struct target_aarch64_ctx);

> 

> If we ever get two different kinds of optional record that need to

> live in the extra space, this is going to need refactoring,

> because at the moment it assumes that the SVE record is the first

> and only thing that might live there. I guess that's OK for now, though.


I'm not quite sure how to generalize this; let's just let the next thing make
that change, once we know what's needed?


r~
Peter Maydell Feb. 23, 2018, 9:59 a.m. | #3
On 22 February 2018 at 20:14, Richard Henderson
<richard.henderson@linaro.org> wrote:
> On 02/22/2018 08:41 AM, Peter Maydell wrote:

>> On 16 February 2018 at 21:56, Richard Henderson

>> <richard.henderson@linaro.org> wrote:


>>> +        if (sve_size <= std_size) {

>>> +            sve_ofs = size;

>>> +            size += sve_size;

>>> +            end1_ofs = size;

>>> +        } else {

>>> +            /* Otherwise we need to allocate extra space.  */

>>> +            extra_ofs = size;

>>> +            size += sizeof(struct target_extra_context);

>>> +            end1_ofs = size;

>>> +            size += QEMU_ALIGN_UP(sizeof(struct target_aarch64_ctx), 16);

>>

>> Why do we add the size of target_aarch64_ctx to size here?

>> We already account for the size of the end record later, so

>> what is this one?

>

> This is for the end record within the extra space, as opposed to the end record

> within the standard space which is what we accounted for before.  A comment

> would help, I supposed.


Oh, so 'size' is accounting for both the standard space used
and the extra space? I had thought that 'size' was just counting
up the standard space used, and the extra space count was in
extra_size.

thanks
-- PMM
Richard Henderson Feb. 23, 2018, 10:23 p.m. | #4
On 02/23/2018 01:59 AM, Peter Maydell wrote:
> On 22 February 2018 at 20:14, Richard Henderson

> <richard.henderson@linaro.org> wrote:

>> On 02/22/2018 08:41 AM, Peter Maydell wrote:

>>> On 16 February 2018 at 21:56, Richard Henderson

>>> <richard.henderson@linaro.org> wrote:

> 

>>>> +        if (sve_size <= std_size) {

>>>> +            sve_ofs = size;

>>>> +            size += sve_size;

>>>> +            end1_ofs = size;

>>>> +        } else {

>>>> +            /* Otherwise we need to allocate extra space.  */

>>>> +            extra_ofs = size;

>>>> +            size += sizeof(struct target_extra_context);

>>>> +            end1_ofs = size;

>>>> +            size += QEMU_ALIGN_UP(sizeof(struct target_aarch64_ctx), 16);

>>>

>>> Why do we add the size of target_aarch64_ctx to size here?

>>> We already account for the size of the end record later, so

>>> what is this one?

>>

>> This is for the end record within the extra space, as opposed to the end record

>> within the standard space which is what we accounted for before.  A comment

>> would help, I supposed.

> 

> Oh, so 'size' is accounting for both the standard space used

> and the extra space? I had thought that 'size' was just counting

> up the standard space used, and the extra space count was in

> extra_size.


Yes.  The revised code uses a different name, total_size, that hopefully makes
this more clear.


r~

Patch

diff --git a/linux-user/signal.c b/linux-user/signal.c
index ca0ba28c98..4c9fef4bb2 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -1452,6 +1452,30 @@  struct target_extra_context {
     uint32_t reserved[3];
 };
 
+#define TARGET_SVE_MAGIC    0x53564501
+
+struct target_sve_context {
+    struct target_aarch64_ctx head;
+    uint16_t vl;
+    uint16_t reserved[3];
+};
+
+#define TARGET_SVE_VQ_BYTES  16
+
+#define TARGET_SVE_SIG_ZREG_SIZE(VQ)  ((VQ) * TARGET_SVE_VQ_BYTES)
+#define TARGET_SVE_SIG_PREG_SIZE(VQ)  ((VQ) * (TARGET_SVE_VQ_BYTES / 8))
+
+#define TARGET_SVE_SIG_REGS_OFFSET \
+    QEMU_ALIGN_UP(sizeof(struct target_sve_context), TARGET_SVE_VQ_BYTES)
+#define TARGET_SVE_SIG_ZREG_OFFSET(VQ, N) \
+    (TARGET_SVE_SIG_REGS_OFFSET + TARGET_SVE_SIG_ZREG_SIZE(VQ) * (N))
+#define TARGET_SVE_SIG_PREG_OFFSET(VQ, N) \
+    (TARGET_SVE_SIG_ZREG_OFFSET(VQ, 32) + TARGET_SVE_SIG_PREG_SIZE(VQ) * (N))
+#define TARGET_SVE_SIG_FFR_OFFSET(VQ) \
+    (TARGET_SVE_SIG_PREG_OFFSET(VQ, 16))
+#define TARGET_SVE_SIG_CONTEXT_SIZE(VQ) \
+    (TARGET_SVE_SIG_PREG_OFFSET(VQ, 17))
+
 struct target_rt_sigframe {
     struct target_siginfo info;
     struct target_ucontext uc;
@@ -1526,6 +1550,34 @@  static void target_setup_end_record(struct target_aarch64_ctx *end)
     __put_user(0, &end->size);
 }
 
+static void target_setup_sve_record(struct target_sve_context *sve,
+                                    CPUARMState *env, int vq, int size)
+{
+    int i, j;
+
+    __put_user(TARGET_SVE_MAGIC, &sve->head.magic);
+    __put_user(size, &sve->head.size);
+    __put_user(vq * TARGET_SVE_VQ_BYTES, &sve->vl);
+
+    /* Note that SVE regs are stored as a byte stream, with each byte element
+     * at a subsequent address.  This corresponds to a little-endian store
+     * of our 64-bit hunks.
+     */
+    for (i = 0; i < 32; ++i) {
+        uint64_t *z = (void *)sve + TARGET_SVE_SIG_ZREG_OFFSET(vq, i);
+        for (j = 0; j < vq * 2; ++j) {
+            __put_user_e(env->vfp.zregs[i].d[j], z + j, le);
+        }
+    }
+    for (i = 0; i <= 16; ++i) {
+        uint16_t *p = (void *)sve + TARGET_SVE_SIG_PREG_OFFSET(vq, i);
+        for (j = 0; j < vq; ++j) {
+            uint64_t r = env->vfp.pregs[i].p[j >> 2];
+            __put_user_e(r >> ((j & 3) * 16), p + j, le);
+        }
+    }
+}
+
 static void target_restore_general_frame(CPUARMState *env,
                                          struct target_rt_sigframe *sf)
 {
@@ -1569,13 +1621,44 @@  static void target_restore_fpsimd_record(CPUARMState *env,
     }
 }
 
+static void target_restore_sve_record(CPUARMState *env,
+                                      struct target_sve_context *sve, int vq)
+{
+    int i, j;
+
+    /* Note that SVE regs are stored as a byte stream, with each byte element
+     * at a subsequent address.  This corresponds to a little-endian store
+     * of our 64-bit hunks.
+     */
+    for (i = 0; i < 32; ++i) {
+        uint64_t *z = (void *)sve + TARGET_SVE_SIG_ZREG_OFFSET(vq, i);
+        for (j = 0; j < vq * 2; ++j) {
+            __get_user_e(env->vfp.zregs[i].d[j], z + j, le);
+        }
+    }
+    for (i = 0; i <= 16; ++i) {
+        uint16_t *p = (void *)sve + TARGET_SVE_SIG_PREG_OFFSET(vq, i);
+        for (j = 0; j < vq; ++j) {
+            uint16_t r;
+            __get_user_e(r, p + j, le);
+            if (j & 3) {
+                env->vfp.pregs[i].p[j >> 2] |= (uint64_t)r << ((j & 3) * 16);
+            } else {
+                env->vfp.pregs[i].p[j >> 2] = r;
+            }
+        }
+    }
+}
+
 static int target_restore_sigframe(CPUARMState *env,
                                    struct target_rt_sigframe *sf)
 {
     struct target_aarch64_ctx *ctx, *extra = NULL;
     struct target_fpsimd_context *fpsimd = NULL;
+    struct target_sve_context *sve = NULL;
     uint64_t extra_datap = 0;
     bool used_extra = false;
+    int vq = 0, sve_size = 0;
 
     target_restore_general_frame(env, sf);
 
@@ -1605,6 +1688,17 @@  static int target_restore_sigframe(CPUARMState *env,
             fpsimd = (struct target_fpsimd_context *)ctx;
             break;
 
+        case TARGET_SVE_MAGIC:
+            if (arm_feature(env, ARM_FEATURE_SVE)) {
+                vq = (env->vfp.zcr_el[1] & 0xf) + 1;
+                sve_size = QEMU_ALIGN_UP(TARGET_SVE_SIG_CONTEXT_SIZE(vq), 16);
+                if (!sve && size == sve_size) {
+                    sve = (struct target_sve_context *)ctx;
+                    break;
+                }
+            }
+            return 1;
+
         case TARGET_EXTRA_MAGIC:
             if (extra || size != sizeof(struct target_extra_context)) {
                 return 1;
@@ -1631,13 +1725,19 @@  static int target_restore_sigframe(CPUARMState *env,
     }
     target_restore_fpsimd_record(env, fpsimd);
 
+    /* SVE data, if present, overwrites FPSIMD data.  */
+    if (sve) {
+        target_restore_sve_record(env, sve, vq);
+    }
+
     if (extra) {
         unlock_user(extra, extra_datap, 0);
     }
     return 0;
 }
 
-static abi_ulong get_sigframe(struct target_sigaction *ka, CPUARMState *env)
+static abi_ulong get_sigframe(struct target_sigaction *ka,
+                              CPUARMState *env, int size)
 {
     abi_ulong sp;
 
@@ -1650,7 +1750,7 @@  static abi_ulong get_sigframe(struct target_sigaction *ka, CPUARMState *env)
         sp = target_sigaltstack_used.ss_sp + target_sigaltstack_used.ss_size;
     }
 
-    sp = (sp - sizeof(struct target_rt_sigframe)) & ~15;
+    sp = (sp - size) & ~15;
 
     return sp;
 }
@@ -1659,21 +1759,53 @@  static void target_setup_frame(int usig, struct target_sigaction *ka,
                                target_siginfo_t *info, target_sigset_t *set,
                                CPUARMState *env)
 {
+    int std_size = sizeof(struct target_rt_sigframe);
     int size = offsetof(struct target_rt_sigframe, uc.tuc_mcontext.__reserved);
     int fpsimd_ofs, end1_ofs, fr_ofs, end2_ofs = 0;
     int extra_ofs = 0, extra_base = 0, extra_size = 0;
+    int sve_ofs = 0, vq = 0, sve_size = 0;
     struct target_rt_sigframe *frame;
     struct target_rt_frame_record *fr;
     abi_ulong frame_addr, return_addr;
 
+    /* Reserve space for standard exit marker.  */
+    std_size -= sizeof(struct target_aarch64_ctx);
+
+    /* FPSIMD record is always in the standard space.  */
     fpsimd_ofs = size;
     size += sizeof(struct target_fpsimd_context);
     end1_ofs = size;
+
+    /* SVE state needs saving only if it exists.  */
+    if (arm_feature(env, ARM_FEATURE_SVE)) {
+        vq = (env->vfp.zcr_el[1] & 0xf) + 1;
+        sve_size = QEMU_ALIGN_UP(TARGET_SVE_SIG_CONTEXT_SIZE(vq), 16);
+
+        /* For VQ <= 6, there is room in the standard space.  */
+        if (sve_size <= std_size) {
+            sve_ofs = size;
+            size += sve_size;
+            end1_ofs = size;
+        } else {
+            /* Otherwise we need to allocate extra space.  */
+            extra_ofs = size;
+            size += sizeof(struct target_extra_context);
+            end1_ofs = size;
+            size += QEMU_ALIGN_UP(sizeof(struct target_aarch64_ctx), 16);
+            extra_base = size;
+            extra_size = sve_size + sizeof(struct target_aarch64_ctx);
+
+            sve_ofs = size;
+            size += sve_size;
+            end2_ofs = size;
+        }
+    }
     size += sizeof(struct target_aarch64_ctx);
+
     fr_ofs = size;
     size += sizeof(struct target_rt_frame_record);
 
-    frame_addr = get_sigframe(ka, env);
+    frame_addr = get_sigframe(ka, env, size);
     trace_user_setup_frame(env, frame_addr);
     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
         goto give_sigsegv;
@@ -1686,6 +1818,9 @@  static void target_setup_frame(int usig, struct target_sigaction *ka,
                                   frame_addr + extra_base, extra_size);
     }
     target_setup_end_record((void *)frame + end1_ofs);
+    if (sve_ofs) {
+        target_setup_sve_record((void *)frame + sve_ofs, env, vq, sve_size);
+    }
     if (end2_ofs) {
         target_setup_end_record((void *)frame + end2_ofs);
     }