arm64/signal: Include TPIDR2 in the signal context

Add a new signal frame record for TPIDR2 using the same format as we
already use for ESR with different magic, a header with the value from the
register appended as the only data. If SME is supported then this record is
always included.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Link: https://lore.kernel.org/r/20221208-arm64-tpidr2-sig-v3-2-c77c6c8775f4@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/uapi/asm/sigcontext.h b/arch/arm64/include/uapi/asm/sigcontext.h
index 9525041e4a1488b1cef97e2d913b39d3c2177765..4b4398d7fb2df8eb79041bf1dc28d16e3b088239 100644 (file)
--- a/arch/arm64/include/uapi/asm/sigcontext.h
+++ b/arch/arm64/include/uapi/asm/sigcontext.h
@@ -144,6 +144,14 @@ struct sve_context {
 
 #define SVE_SIG_FLAG_SM        0x1     /* Context describes streaming mode */
 
+/* TPIDR2_EL0 context */
+#define TPIDR2_MAGIC   0x54504902
+
+struct tpidr2_context {
+       struct _aarch64_ctx head;
+       __u64 tpidr2;
+};
+
 #define ZA_MAGIC       0x54366345
 
 struct za_context {

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index e0d09bf5b01b80a8ed637bc1f0dd51168f0a55a2..5fe45c7c5e4fe06ff9be44f028eb6ba2b2cc8160 100644 (file)
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -56,6 +56,7 @@ struct rt_sigframe_user_layout {
        unsigned long fpsimd_offset;
        unsigned long esr_offset;
        unsigned long sve_offset;
+       unsigned long tpidr2_offset;
        unsigned long za_offset;
        unsigned long extra_offset;
        unsigned long end_offset;
@@ -220,6 +221,7 @@ static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
 struct user_ctxs {
        struct fpsimd_context __user *fpsimd;
        struct sve_context __user *sve;
+       struct tpidr2_context __user *tpidr2;
        struct za_context __user *za;
 };
 
@@ -361,6 +363,32 @@ extern int preserve_sve_context(void __user *ctx);
 
 #ifdef CONFIG_ARM64_SME
 
+static int preserve_tpidr2_context(struct tpidr2_context __user *ctx)
+{
+       int err = 0;
+
+       current->thread.tpidr2_el0 = read_sysreg_s(SYS_TPIDR2_EL0);
+
+       __put_user_error(TPIDR2_MAGIC, &ctx->head.magic, err);
+       __put_user_error(sizeof(*ctx), &ctx->head.size, err);
+       __put_user_error(current->thread.tpidr2_el0, &ctx->tpidr2, err);
+
+       return err;
+}
+
+static int restore_tpidr2_context(struct user_ctxs *user)
+{
+       u64 tpidr2_el0;
+       int err = 0;
+
+       /* Magic and size were validated deciding to call this function */
+       __get_user_error(tpidr2_el0, &user->tpidr2->tpidr2, err);
+       if (!err)
+               current->thread.tpidr2_el0 = tpidr2_el0;
+
+       return err;
+}
+
 static int preserve_za_context(struct za_context __user *ctx)
 {
        int err = 0;
@@ -450,6 +478,8 @@ static int restore_za_context(struct user_ctxs *user)
 #else /* ! CONFIG_ARM64_SME */
 
 /* Turn any non-optimised out attempts to use these into a link error: */
+extern int preserve_tpidr2_context(void __user *ctx);
+extern int restore_tpidr2_context(struct user_ctxs *user);
 extern int preserve_za_context(void __user *ctx);
 extern int restore_za_context(struct user_ctxs *user);
 
@@ -468,6 +498,7 @@ static int parse_user_sigframe(struct user_ctxs *user,
 
        user->fpsimd = NULL;
        user->sve = NULL;
+       user->tpidr2 = NULL;
        user->za = NULL;
 
        if (!IS_ALIGNED((unsigned long)base, 16))
@@ -534,6 +565,19 @@ static int parse_user_sigframe(struct user_ctxs *user,
                        user->sve = (struct sve_context __user *)head;
                        break;
 
+               case TPIDR2_MAGIC:
+                       if (!system_supports_sme())
+                               goto invalid;
+
+                       if (user->tpidr2)
+                               goto invalid;
+
+                       if (size != sizeof(*user->tpidr2))
+                               goto invalid;
+
+                       user->tpidr2 = (struct tpidr2_context __user *)head;
+                       break;
+
                case ZA_MAGIC:
                        if (!system_supports_sme())
                                goto invalid;
@@ -666,6 +710,9 @@ static int restore_sigframe(struct pt_regs *regs,
                        err = restore_fpsimd_context(user.fpsimd);
        }
 
+       if (err == 0 && system_supports_sme() && user.tpidr2)
+               err = restore_tpidr2_context(&user);
+
        if (err == 0 && system_supports_sme() && user.za)
                err = restore_za_context(&user);
 
@@ -760,6 +807,11 @@ static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
                else
                        vl = task_get_sme_vl(current);
 
+               err = sigframe_alloc(user, &user->tpidr2_offset,
+                                    sizeof(struct tpidr2_context));
+               if (err)
+                       return err;
+
                if (thread_za_enabled(&current->thread))
                        vq = sve_vq_from_vl(vl);
 
@@ -817,6 +869,13 @@ static int setup_sigframe(struct rt_sigframe_user_layout *user,
                err |= preserve_sve_context(sve_ctx);
        }
 
+       /* TPIDR2 if supported */
+       if (system_supports_sme() && err == 0) {
+               struct tpidr2_context __user *tpidr2_ctx =
+                       apply_user_offset(user, user->tpidr2_offset);
+               err |= preserve_tpidr2_context(tpidr2_ctx);
+       }
+
        /* ZA state if present */
        if (system_supports_sme() && err == 0 && user->za_offset) {
                struct za_context __user *za_ctx =