[v2,2/8] AArch64: Use HWCAP to detect pauth feature
Commit Message
Add aarch64_get_hwcap functions for reading the HWCAP.
From this extract the PACA value and use this to enable pauth.
gdb/ChangeLog:
2019-03-06 Alan Hayward <alan.hayward@arm.com>
Jiong Wang <jiong.wang@arm.com>
* aarch64-linux-nat.c
(aarch64_linux_nat_target::read_description): Read PACA hwcap.
* aarch64-linux-tdep.c
(aarch64_linux_core_read_description): Likewise.
(aarch64_linux_get_hwcap): New function.
* aarch64-linux-tdep.h (AARCH64_HWCAP_PACA): New define.
(aarch64_linux_get_hwcap): New declaration.
gdb/gdbserver/ChangeLog:
2019-03-06 Alan Hayward <alan.hayward@arm.com>
Jiong Wang <jiong.wang@arm.com>
* linux-aarch64-low.c (AARCH64_HWCAP_PACA): New define.
(aarch64_get_hwcap): New function.
(aarch64_arch_setup): Read APIA hwcap.
---
gdb/aarch64-linux-nat.c | 7 +++++--
gdb/aarch64-linux-tdep.c | 16 +++++++++++----
gdb/aarch64-linux-tdep.h | 6 ++++++
gdb/gdbserver/linux-aarch64-low.c | 33 +++++++++++++++++++++++++++++--
4 files changed, 54 insertions(+), 8 deletions(-)
Comments
On 2019-03-06 8:33 a.m., Alan Hayward wrote:
> Add aarch64_get_hwcap functions for reading the HWCAP.
> From this extract the PACA value and use this to enable pauth.
>
> gdb/ChangeLog:
>
> 2019-03-06 Alan Hayward <alan.hayward@arm.com>
> Jiong Wang <jiong.wang@arm.com>
>
> * aarch64-linux-nat.c
> (aarch64_linux_nat_target::read_description): Read PACA hwcap.
> * aarch64-linux-tdep.c
> (aarch64_linux_core_read_description): Likewise.
> (aarch64_linux_get_hwcap): New function.
> * aarch64-linux-tdep.h (AARCH64_HWCAP_PACA): New define.
> (aarch64_linux_get_hwcap): New declaration.
>
> gdb/gdbserver/ChangeLog:
>
> 2019-03-06 Alan Hayward <alan.hayward@arm.com>
> Jiong Wang <jiong.wang@arm.com>
>
> * linux-aarch64-low.c (AARCH64_HWCAP_PACA): New define.
> (aarch64_get_hwcap): New function.
> (aarch64_arch_setup): Read APIA hwcap.
> ---
> gdb/aarch64-linux-nat.c | 7 +++++--
> gdb/aarch64-linux-tdep.c | 16 +++++++++++----
> gdb/aarch64-linux-tdep.h | 6 ++++++
> gdb/gdbserver/linux-aarch64-low.c | 33 +++++++++++++++++++++++++++++--
> 4 files changed, 54 insertions(+), 8 deletions(-)
>
> diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
> index f58a41e195..8a7006165e 100644
> --- a/gdb/aarch64-linux-nat.c
> +++ b/gdb/aarch64-linux-nat.c
> @@ -606,8 +606,11 @@ aarch64_linux_nat_target::read_description ()
> if (ret == 0)
> return tdesc_arm_with_neon;
>
> - /* pauth not yet supported. */
> - return aarch64_read_description (aarch64_sve_get_vq (tid), false);
> + CORE_ADDR hwcap = 0;
> + bool pauth_p = aarch64_linux_get_hwcap (&hwcap)
> + && (hwcap & AARCH64_HWCAP_PACA);
> +
> + return aarch64_read_description (aarch64_sve_get_vq (tid), pauth_p);
> }
>
> /* Convert a native/host siginfo object, into/from the siginfo in the
> diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
> index 445019accc..5eeafa456c 100644
> --- a/gdb/aarch64-linux-tdep.c
> +++ b/gdb/aarch64-linux-tdep.c
> @@ -637,12 +637,11 @@ aarch64_linux_core_read_description (struct gdbarch *gdbarch,
> {
> CORE_ADDR aarch64_hwcap = 0;
>
> - if (target_auxv_search (target, AT_HWCAP, &aarch64_hwcap) != 1)
> - return NULL;
> + if (!aarch64_linux_get_hwcap (&aarch64_hwcap))
> + return nullptr;
>
> - /* pauth not yet supported. */
> return aarch64_read_description (aarch64_linux_core_read_vq (gdbarch, abfd),
> - false);
> + aarch64_hwcap & AARCH64_HWCAP_PACA);
> }
>
> /* Implementation of `gdbarch_stap_is_single_operand', as defined in
> @@ -1420,6 +1419,15 @@ aarch64_linux_gcc_target_options (struct gdbarch *gdbarch)
> return NULL;
> }
>
> +/* See aarch64-linux-tdep.h. */
> +
> +bool
> +aarch64_linux_get_hwcap (CORE_ADDR *hwcap)
> +{
> + *hwcap = 0;
> + return target_auxv_search (current_top_target (), AT_HWCAP, hwcap) == 1;
> +}
> +
I don't know if it actually matters, but when the target_aux_search call
was in aarch64_linux_core_read_description, it used the TARGET
parameter, rather than using current_top_target. So, perhaps that new
function should take a target_ops parameter and use it? The other call
in aarch64_linux_nat_target::read_description would pass "this".
And this function does nothing AArch64-specific, so I think it would be
nice to have it in linux-tdep.{h,c} and update other arches to use it.
But I would say, don't bother with that in this series, we can do it after.
Simon
@@ -606,8 +606,11 @@ aarch64_linux_nat_target::read_description ()
if (ret == 0)
return tdesc_arm_with_neon;
- /* pauth not yet supported. */
- return aarch64_read_description (aarch64_sve_get_vq (tid), false);
+ CORE_ADDR hwcap = 0;
+ bool pauth_p = aarch64_linux_get_hwcap (&hwcap)
+ && (hwcap & AARCH64_HWCAP_PACA);
+
+ return aarch64_read_description (aarch64_sve_get_vq (tid), pauth_p);
}
/* Convert a native/host siginfo object, into/from the siginfo in the
@@ -637,12 +637,11 @@ aarch64_linux_core_read_description (struct gdbarch *gdbarch,
{
CORE_ADDR aarch64_hwcap = 0;
- if (target_auxv_search (target, AT_HWCAP, &aarch64_hwcap) != 1)
- return NULL;
+ if (!aarch64_linux_get_hwcap (&aarch64_hwcap))
+ return nullptr;
- /* pauth not yet supported. */
return aarch64_read_description (aarch64_linux_core_read_vq (gdbarch, abfd),
- false);
+ aarch64_hwcap & AARCH64_HWCAP_PACA);
}
/* Implementation of `gdbarch_stap_is_single_operand', as defined in
@@ -1420,6 +1419,15 @@ aarch64_linux_gcc_target_options (struct gdbarch *gdbarch)
return NULL;
}
+/* See aarch64-linux-tdep.h. */
+
+bool
+aarch64_linux_get_hwcap (CORE_ADDR *hwcap)
+{
+ *hwcap = 0;
+ return target_auxv_search (current_top_target (), AT_HWCAP, hwcap) == 1;
+}
+
static void
aarch64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
@@ -36,4 +36,10 @@
extern const struct regset aarch64_linux_gregset;
extern const struct regset aarch64_linux_fpregset;
+/* Matches HWCAP_PACA in kernel header arch/arm64/include/uapi/asm/hwcap.h. */
+#define AARCH64_HWCAP_PACA (1 << 30)
+
+/* Fetch the AT_HWCAP entry from the auxv vector. */
+bool aarch64_linux_get_hwcap (CORE_ADDR *hwcap);
+
#endif /* AARCH64_LINUX_TDEP_H */
@@ -485,6 +485,33 @@ aarch64_linux_new_fork (struct process_info *parent,
*child->priv->arch_private = *parent->priv->arch_private;
}
+/* Matches HWCAP_PACA in kernel header arch/arm64/include/uapi/asm/hwcap.h. */
+#define AARCH64_HWCAP_PACA (1 << 30)
+
+/* Fetch the AT_HWCAP entry from the auxv vector. */
+
+static bool
+aarch64_get_hwcap (unsigned long *valp)
+{
+ unsigned char *data = (unsigned char *) alloca (16);
+ int offset = 0;
+
+ while ((*the_target->read_auxv) (offset, data, 16) == 16)
+ {
+ unsigned long *data_p = (unsigned long *)data;
+ if (data_p[0] == AT_HWCAP)
+ {
+ *valp = data_p[1];
+ return true;
+ }
+
+ offset += 16;
+ }
+
+ *valp = 0;
+ return false;
+}
+
/* Implementation of linux_target_ops method "arch_setup". */
static void
@@ -501,8 +528,10 @@ aarch64_arch_setup (void)
if (is_elf64)
{
uint64_t vq = aarch64_sve_get_vq (tid);
- /* pauth not yet supported. */
- current_process ()->tdesc = aarch64_linux_read_description (vq, false);
+ unsigned long hwcap = 0;
+ bool pauth_p = aarch64_get_hwcap (&hwcap) && (hwcap & AARCH64_HWCAP_PACA);
+
+ current_process ()->tdesc = aarch64_linux_read_description (vq, pauth_p);
}
else
current_process ()->tdesc = tdesc_arm_with_neon;