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-rw-r--r--arch/arm64/kernel/signal.c1587
1 files changed, 1441 insertions, 146 deletions
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 890a591f75dd..1110eeb21f57 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -1,57 +1,260 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* Based on arch/arm/kernel/signal.c
*
* Copyright (C) 1995-2009 Russell King
* Copyright (C) 2012 ARM Ltd.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <linux/cache.h>
+#include <linux/compat.h>
#include <linux/errno.h>
+#include <linux/irq-entry-common.h>
+#include <linux/kernel.h>
#include <linux/signal.h>
-#include <linux/personality.h>
#include <linux/freezer.h>
+#include <linux/stddef.h>
#include <linux/uaccess.h>
-#include <linux/tracehook.h>
+#include <linux/sizes.h>
+#include <linux/string.h>
#include <linux/ratelimit.h>
+#include <linux/rseq.h>
+#include <linux/syscalls.h>
+#include <linux/pkeys.h>
-#include <asm/compat.h>
+#include <asm/daifflags.h>
#include <asm/debug-monitors.h>
#include <asm/elf.h>
+#include <asm/exception.h>
#include <asm/cacheflush.h>
+#include <asm/gcs.h>
#include <asm/ucontext.h>
#include <asm/unistd.h>
#include <asm/fpsimd.h>
+#include <asm/ptrace.h>
+#include <asm/syscall.h>
#include <asm/signal32.h>
+#include <asm/traps.h>
#include <asm/vdso.h>
+#define GCS_SIGNAL_CAP(addr) (((unsigned long)addr) & GCS_CAP_ADDR_MASK)
+
/*
* Do a signal return; undo the signal stack. These are aligned to 128-bit.
*/
struct rt_sigframe {
struct siginfo info;
struct ucontext uc;
- u64 fp;
- u64 lr;
+};
+
+struct rt_sigframe_user_layout {
+ struct rt_sigframe __user *sigframe;
+ struct frame_record __user *next_frame;
+
+ unsigned long size; /* size of allocated sigframe data */
+ unsigned long limit; /* largest allowed size */
+
+ unsigned long fpsimd_offset;
+ unsigned long esr_offset;
+ unsigned long gcs_offset;
+ unsigned long sve_offset;
+ unsigned long tpidr2_offset;
+ unsigned long za_offset;
+ unsigned long zt_offset;
+ unsigned long fpmr_offset;
+ unsigned long poe_offset;
+ unsigned long extra_offset;
+ unsigned long end_offset;
+};
+
+/*
+ * Holds any EL0-controlled state that influences unprivileged memory accesses.
+ * This includes both accesses done in userspace and uaccess done in the kernel.
+ *
+ * This state needs to be carefully managed to ensure that it doesn't cause
+ * uaccess to fail when setting up the signal frame, and the signal handler
+ * itself also expects a well-defined state when entered.
+ */
+struct user_access_state {
+ u64 por_el0;
+};
+
+#define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16)
+#define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16)
+
+/*
+ * Save the user access state into ua_state and reset it to disable any
+ * restrictions.
+ */
+static void save_reset_user_access_state(struct user_access_state *ua_state)
+{
+ if (system_supports_poe()) {
+ u64 por_enable_all = 0;
+
+ for (int pkey = 0; pkey < arch_max_pkey(); pkey++)
+ por_enable_all |= POR_ELx_PERM_PREP(pkey, POE_RWX);
+
+ ua_state->por_el0 = read_sysreg_s(SYS_POR_EL0);
+ write_sysreg_s(por_enable_all, SYS_POR_EL0);
+ /*
+ * No ISB required as we can tolerate spurious Overlay faults -
+ * the fault handler will check again based on the new value
+ * of POR_EL0.
+ */
+ }
+}
+
+/*
+ * Set the user access state for invoking the signal handler.
+ *
+ * No uaccess should be done after that function is called.
+ */
+static void set_handler_user_access_state(void)
+{
+ if (system_supports_poe())
+ write_sysreg_s(POR_EL0_INIT, SYS_POR_EL0);
+}
+
+/*
+ * Restore the user access state to the values saved in ua_state.
+ *
+ * No uaccess should be done after that function is called.
+ */
+static void restore_user_access_state(const struct user_access_state *ua_state)
+{
+ if (system_supports_poe())
+ write_sysreg_s(ua_state->por_el0, SYS_POR_EL0);
+}
+
+static void init_user_layout(struct rt_sigframe_user_layout *user)
+{
+ const size_t reserved_size =
+ sizeof(user->sigframe->uc.uc_mcontext.__reserved);
+
+ memset(user, 0, sizeof(*user));
+ user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved);
+
+ user->limit = user->size + reserved_size;
+
+ user->limit -= TERMINATOR_SIZE;
+ user->limit -= EXTRA_CONTEXT_SIZE;
+ /* Reserve space for extension and terminator ^ */
+}
+
+static size_t sigframe_size(struct rt_sigframe_user_layout const *user)
+{
+ return round_up(max(user->size, sizeof(struct rt_sigframe)), 16);
+}
+
+/*
+ * Sanity limit on the approximate maximum size of signal frame we'll
+ * try to generate. Stack alignment padding and the frame record are
+ * not taken into account. This limit is not a guarantee and is
+ * NOT ABI.
+ */
+#define SIGFRAME_MAXSZ SZ_256K
+
+static int __sigframe_alloc(struct rt_sigframe_user_layout *user,
+ unsigned long *offset, size_t size, bool extend)
+{
+ size_t padded_size = round_up(size, 16);
+
+ if (padded_size > user->limit - user->size &&
+ !user->extra_offset &&
+ extend) {
+ int ret;
+
+ user->limit += EXTRA_CONTEXT_SIZE;
+ ret = __sigframe_alloc(user, &user->extra_offset,
+ sizeof(struct extra_context), false);
+ if (ret) {
+ user->limit -= EXTRA_CONTEXT_SIZE;
+ return ret;
+ }
+
+ /* Reserve space for the __reserved[] terminator */
+ user->size += TERMINATOR_SIZE;
+
+ /*
+ * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for
+ * the terminator:
+ */
+ user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE;
+ }
+
+ /* Still not enough space? Bad luck! */
+ if (padded_size > user->limit - user->size)
+ return -ENOMEM;
+
+ *offset = user->size;
+ user->size += padded_size;
+
+ return 0;
+}
+
+/*
+ * Allocate space for an optional record of <size> bytes in the user
+ * signal frame. The offset from the signal frame base address to the
+ * allocated block is assigned to *offset.
+ */
+static int sigframe_alloc(struct rt_sigframe_user_layout *user,
+ unsigned long *offset, size_t size)
+{
+ return __sigframe_alloc(user, offset, size, true);
+}
+
+/* Allocate the null terminator record and prevent further allocations */
+static int sigframe_alloc_end(struct rt_sigframe_user_layout *user)
+{
+ int ret;
+
+ /* Un-reserve the space reserved for the terminator: */
+ user->limit += TERMINATOR_SIZE;
+
+ ret = sigframe_alloc(user, &user->end_offset,
+ sizeof(struct _aarch64_ctx));
+ if (ret)
+ return ret;
+
+ /* Prevent further allocation: */
+ user->limit = user->size;
+ return 0;
+}
+
+static void __user *apply_user_offset(
+ struct rt_sigframe_user_layout const *user, unsigned long offset)
+{
+ char __user *base = (char __user *)user->sigframe;
+
+ return base + offset;
+}
+
+struct user_ctxs {
+ struct fpsimd_context __user *fpsimd;
+ u32 fpsimd_size;
+ struct sve_context __user *sve;
+ u32 sve_size;
+ struct tpidr2_context __user *tpidr2;
+ u32 tpidr2_size;
+ struct za_context __user *za;
+ u32 za_size;
+ struct zt_context __user *zt;
+ u32 zt_size;
+ struct fpmr_context __user *fpmr;
+ u32 fpmr_size;
+ struct poe_context __user *poe;
+ u32 poe_size;
+ struct gcs_context __user *gcs;
+ u32 gcs_size;
};
static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
{
- struct fpsimd_state *fpsimd = &current->thread.fpsimd_state;
+ struct user_fpsimd_state const *fpsimd =
+ &current->thread.uw.fpsimd_state;
int err;
- /* dump the hardware registers to the fpsimd_state structure */
- fpsimd_save_state(fpsimd);
+ fpsimd_sync_from_effective_state(current);
/* copy the FP and status/control registers */
err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
@@ -65,43 +268,709 @@ static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
return err ? -EFAULT : 0;
}
-static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
+static int read_fpsimd_context(struct user_fpsimd_state *fpsimd,
+ struct user_ctxs *user)
+{
+ int err;
+
+ /* check the size information */
+ if (user->fpsimd_size != sizeof(struct fpsimd_context))
+ return -EINVAL;
+
+ /* copy the FP and status/control registers */
+ err = __copy_from_user(fpsimd->vregs, &(user->fpsimd->vregs),
+ sizeof(fpsimd->vregs));
+ __get_user_error(fpsimd->fpsr, &(user->fpsimd->fpsr), err);
+ __get_user_error(fpsimd->fpcr, &(user->fpsimd->fpcr), err);
+
+ return err ? -EFAULT : 0;
+}
+
+static int restore_fpsimd_context(struct user_ctxs *user)
+{
+ struct user_fpsimd_state fpsimd;
+ int err;
+
+ err = read_fpsimd_context(&fpsimd, user);
+ if (err)
+ return err;
+
+ clear_thread_flag(TIF_SVE);
+ current->thread.svcr &= ~SVCR_SM_MASK;
+ current->thread.fp_type = FP_STATE_FPSIMD;
+
+ /* load the hardware registers from the fpsimd_state structure */
+ fpsimd_update_current_state(&fpsimd);
+ return 0;
+}
+
+static int preserve_fpmr_context(struct fpmr_context __user *ctx)
{
- struct fpsimd_state fpsimd;
- __u32 magic, size;
int err = 0;
- /* check the magic/size information */
- __get_user_error(magic, &ctx->head.magic, err);
- __get_user_error(size, &ctx->head.size, err);
+ __put_user_error(FPMR_MAGIC, &ctx->head.magic, err);
+ __put_user_error(sizeof(*ctx), &ctx->head.size, err);
+ __put_user_error(current->thread.uw.fpmr, &ctx->fpmr, err);
+
+ return err;
+}
+
+static int restore_fpmr_context(struct user_ctxs *user)
+{
+ u64 fpmr;
+ int err = 0;
+
+ if (user->fpmr_size != sizeof(*user->fpmr))
+ return -EINVAL;
+
+ __get_user_error(fpmr, &user->fpmr->fpmr, err);
+ if (!err)
+ current->thread.uw.fpmr = fpmr;
+
+ return err;
+}
+
+static int preserve_poe_context(struct poe_context __user *ctx,
+ const struct user_access_state *ua_state)
+{
+ int err = 0;
+
+ __put_user_error(POE_MAGIC, &ctx->head.magic, err);
+ __put_user_error(sizeof(*ctx), &ctx->head.size, err);
+ __put_user_error(ua_state->por_el0, &ctx->por_el0, err);
+
+ return err;
+}
+
+static int restore_poe_context(struct user_ctxs *user,
+ struct user_access_state *ua_state)
+{
+ u64 por_el0;
+ int err = 0;
+
+ if (user->poe_size != sizeof(*user->poe))
+ return -EINVAL;
+
+ __get_user_error(por_el0, &(user->poe->por_el0), err);
+ if (!err)
+ ua_state->por_el0 = por_el0;
+
+ return err;
+}
+
+#ifdef CONFIG_ARM64_SVE
+
+static int preserve_sve_context(struct sve_context __user *ctx)
+{
+ int err = 0;
+ u16 reserved[ARRAY_SIZE(ctx->__reserved)];
+ u16 flags = 0;
+ unsigned int vl = task_get_sve_vl(current);
+ unsigned int vq = 0;
+
+ if (thread_sm_enabled(&current->thread)) {
+ vl = task_get_sme_vl(current);
+ vq = sve_vq_from_vl(vl);
+ flags |= SVE_SIG_FLAG_SM;
+ } else if (current->thread.fp_type == FP_STATE_SVE) {
+ vq = sve_vq_from_vl(vl);
+ }
+
+ memset(reserved, 0, sizeof(reserved));
+
+ __put_user_error(SVE_MAGIC, &ctx->head.magic, err);
+ __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16),
+ &ctx->head.size, err);
+ __put_user_error(vl, &ctx->vl, err);
+ __put_user_error(flags, &ctx->flags, err);
+ BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
+ err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
+
+ if (vq) {
+ err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET,
+ current->thread.sve_state,
+ SVE_SIG_REGS_SIZE(vq));
+ }
+
+ return err ? -EFAULT : 0;
+}
+
+static int restore_sve_fpsimd_context(struct user_ctxs *user)
+{
+ int err = 0;
+ unsigned int vl, vq;
+ struct user_fpsimd_state fpsimd;
+ u16 user_vl, flags;
+ bool sm;
+
+ if (user->sve_size < sizeof(*user->sve))
+ return -EINVAL;
+
+ __get_user_error(user_vl, &(user->sve->vl), err);
+ __get_user_error(flags, &(user->sve->flags), err);
+ if (err)
+ return err;
+
+ sm = flags & SVE_SIG_FLAG_SM;
+ if (sm) {
+ if (!system_supports_sme())
+ return -EINVAL;
+
+ vl = task_get_sme_vl(current);
+ } else {
+ /*
+ * A SME only system use SVE for streaming mode so can
+ * have a SVE formatted context with a zero VL and no
+ * payload data.
+ */
+ if (!system_supports_sve() && !system_supports_sme())
+ return -EINVAL;
+
+ vl = task_get_sve_vl(current);
+ }
+
+ if (user_vl != vl)
+ return -EINVAL;
+
+ /*
+ * Non-streaming SVE state may be preserved without an SVE payload, in
+ * which case the SVE context only has a header with VL==0, and all
+ * state can be restored from the FPSIMD context.
+ *
+ * Streaming SVE state is always preserved with an SVE payload. For
+ * consistency and robustness, reject restoring streaming SVE state
+ * without an SVE payload.
+ */
+ if (!sm && user->sve_size == sizeof(*user->sve))
+ return restore_fpsimd_context(user);
+
+ vq = sve_vq_from_vl(vl);
+
+ if (user->sve_size < SVE_SIG_CONTEXT_SIZE(vq))
+ return -EINVAL;
+
+ sve_alloc(current, true);
+ if (!current->thread.sve_state) {
+ clear_thread_flag(TIF_SVE);
+ return -ENOMEM;
+ }
+
+ err = __copy_from_user(current->thread.sve_state,
+ (char __user const *)user->sve +
+ SVE_SIG_REGS_OFFSET,
+ SVE_SIG_REGS_SIZE(vq));
if (err)
return -EFAULT;
- if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
+
+ if (flags & SVE_SIG_FLAG_SM)
+ current->thread.svcr |= SVCR_SM_MASK;
+ else
+ set_thread_flag(TIF_SVE);
+ current->thread.fp_type = FP_STATE_SVE;
+
+ err = read_fpsimd_context(&fpsimd, user);
+ if (err)
+ return err;
+
+ /* Merge the FPSIMD registers into the SVE state */
+ fpsimd_update_current_state(&fpsimd);
+
+ return 0;
+}
+
+#else /* ! CONFIG_ARM64_SVE */
+
+static int restore_sve_fpsimd_context(struct user_ctxs *user)
+{
+ WARN_ON_ONCE(1);
+ return -EINVAL;
+}
+
+/* Turn any non-optimised out attempts to use this into a link error: */
+extern int preserve_sve_context(void __user *ctx);
+
+#endif /* ! CONFIG_ARM64_SVE */
+
+#ifdef CONFIG_ARM64_SME
+
+static int preserve_tpidr2_context(struct tpidr2_context __user *ctx)
+{
+ u64 tpidr2_el0 = read_sysreg_s(SYS_TPIDR2_EL0);
+ int err = 0;
+
+ __put_user_error(TPIDR2_MAGIC, &ctx->head.magic, err);
+ __put_user_error(sizeof(*ctx), &ctx->head.size, err);
+ __put_user_error(tpidr2_el0, &ctx->tpidr2, err);
+
+ return err;
+}
+
+static int restore_tpidr2_context(struct user_ctxs *user)
+{
+ u64 tpidr2_el0;
+ int err = 0;
+
+ if (user->tpidr2_size != sizeof(*user->tpidr2))
return -EINVAL;
- /* copy the FP and status/control registers */
- err = __copy_from_user(fpsimd.vregs, ctx->vregs,
- sizeof(fpsimd.vregs));
- __get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
- __get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
+ __get_user_error(tpidr2_el0, &user->tpidr2->tpidr2, err);
+ if (!err)
+ write_sysreg_s(tpidr2_el0, SYS_TPIDR2_EL0);
- /* load the hardware registers from the fpsimd_state structure */
- if (!err) {
- preempt_disable();
- fpsimd_load_state(&fpsimd);
- preempt_enable();
+ return err;
+}
+
+static int preserve_za_context(struct za_context __user *ctx)
+{
+ int err = 0;
+ u16 reserved[ARRAY_SIZE(ctx->__reserved)];
+ unsigned int vl = task_get_sme_vl(current);
+ unsigned int vq;
+
+ if (thread_za_enabled(&current->thread))
+ vq = sve_vq_from_vl(vl);
+ else
+ vq = 0;
+
+ memset(reserved, 0, sizeof(reserved));
+
+ __put_user_error(ZA_MAGIC, &ctx->head.magic, err);
+ __put_user_error(round_up(ZA_SIG_CONTEXT_SIZE(vq), 16),
+ &ctx->head.size, err);
+ __put_user_error(vl, &ctx->vl, err);
+ BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
+ err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
+
+ if (vq) {
+ err |= __copy_to_user((char __user *)ctx + ZA_SIG_REGS_OFFSET,
+ current->thread.sme_state,
+ ZA_SIG_REGS_SIZE(vq));
}
return err ? -EFAULT : 0;
}
+static int restore_za_context(struct user_ctxs *user)
+{
+ int err = 0;
+ unsigned int vq;
+ u16 user_vl;
+
+ if (user->za_size < sizeof(*user->za))
+ return -EINVAL;
+
+ __get_user_error(user_vl, &(user->za->vl), err);
+ if (err)
+ return err;
+
+ if (user_vl != task_get_sme_vl(current))
+ return -EINVAL;
+
+ if (user->za_size == sizeof(*user->za)) {
+ current->thread.svcr &= ~SVCR_ZA_MASK;
+ return 0;
+ }
+
+ vq = sve_vq_from_vl(user_vl);
+
+ if (user->za_size < ZA_SIG_CONTEXT_SIZE(vq))
+ return -EINVAL;
+
+ sme_alloc(current, true);
+ if (!current->thread.sme_state) {
+ current->thread.svcr &= ~SVCR_ZA_MASK;
+ clear_thread_flag(TIF_SME);
+ return -ENOMEM;
+ }
+
+ err = __copy_from_user(current->thread.sme_state,
+ (char __user const *)user->za +
+ ZA_SIG_REGS_OFFSET,
+ ZA_SIG_REGS_SIZE(vq));
+ if (err)
+ return -EFAULT;
+
+ set_thread_flag(TIF_SME);
+ current->thread.svcr |= SVCR_ZA_MASK;
+
+ return 0;
+}
+
+static int preserve_zt_context(struct zt_context __user *ctx)
+{
+ int err = 0;
+ u16 reserved[ARRAY_SIZE(ctx->__reserved)];
+
+ if (WARN_ON(!thread_za_enabled(&current->thread)))
+ return -EINVAL;
+
+ memset(reserved, 0, sizeof(reserved));
+
+ __put_user_error(ZT_MAGIC, &ctx->head.magic, err);
+ __put_user_error(round_up(ZT_SIG_CONTEXT_SIZE(1), 16),
+ &ctx->head.size, err);
+ __put_user_error(1, &ctx->nregs, err);
+ BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved));
+ err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved));
+
+ err |= __copy_to_user((char __user *)ctx + ZT_SIG_REGS_OFFSET,
+ thread_zt_state(&current->thread),
+ ZT_SIG_REGS_SIZE(1));
+
+ return err ? -EFAULT : 0;
+}
+
+static int restore_zt_context(struct user_ctxs *user)
+{
+ int err;
+ u16 nregs;
+
+ /* ZA must be restored first for this check to be valid */
+ if (!thread_za_enabled(&current->thread))
+ return -EINVAL;
+
+ if (user->zt_size != ZT_SIG_CONTEXT_SIZE(1))
+ return -EINVAL;
+
+ if (__copy_from_user(&nregs, &(user->zt->nregs), sizeof(nregs)))
+ return -EFAULT;
+
+ if (nregs != 1)
+ return -EINVAL;
+
+ err = __copy_from_user(thread_zt_state(&current->thread),
+ (char __user const *)user->zt +
+ ZT_SIG_REGS_OFFSET,
+ ZT_SIG_REGS_SIZE(1));
+ if (err)
+ return -EFAULT;
+
+ return 0;
+}
+
+#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);
+extern int preserve_zt_context(void __user *ctx);
+extern int restore_zt_context(struct user_ctxs *user);
+
+#endif /* ! CONFIG_ARM64_SME */
+
+#ifdef CONFIG_ARM64_GCS
+
+static int preserve_gcs_context(struct gcs_context __user *ctx)
+{
+ int err = 0;
+ u64 gcspr = read_sysreg_s(SYS_GCSPR_EL0);
+
+ /*
+ * If GCS is enabled we will add a cap token to the frame,
+ * include it in the GCSPR_EL0 we report to support stack
+ * switching via sigreturn if GCS is enabled. We do not allow
+ * enabling via sigreturn so the token is only relevant for
+ * threads with GCS enabled.
+ */
+ if (task_gcs_el0_enabled(current))
+ gcspr -= 8;
+
+ __put_user_error(GCS_MAGIC, &ctx->head.magic, err);
+ __put_user_error(sizeof(*ctx), &ctx->head.size, err);
+ __put_user_error(gcspr, &ctx->gcspr, err);
+ __put_user_error(0, &ctx->reserved, err);
+ __put_user_error(current->thread.gcs_el0_mode,
+ &ctx->features_enabled, err);
+
+ return err;
+}
+
+static int restore_gcs_context(struct user_ctxs *user)
+{
+ u64 gcspr, enabled;
+ int err = 0;
+
+ if (user->gcs_size != sizeof(*user->gcs))
+ return -EINVAL;
+
+ __get_user_error(gcspr, &user->gcs->gcspr, err);
+ __get_user_error(enabled, &user->gcs->features_enabled, err);
+ if (err)
+ return err;
+
+ /* Don't allow unknown modes */
+ if (enabled & ~PR_SHADOW_STACK_SUPPORTED_STATUS_MASK)
+ return -EINVAL;
+
+ err = gcs_check_locked(current, enabled);
+ if (err != 0)
+ return err;
+
+ /* Don't allow enabling */
+ if (!task_gcs_el0_enabled(current) &&
+ (enabled & PR_SHADOW_STACK_ENABLE))
+ return -EINVAL;
+
+ /* If we are disabling disable everything */
+ if (!(enabled & PR_SHADOW_STACK_ENABLE))
+ enabled = 0;
+
+ current->thread.gcs_el0_mode = enabled;
+
+ /*
+ * We let userspace set GCSPR_EL0 to anything here, we will
+ * validate later in gcs_restore_signal().
+ */
+ write_sysreg_s(gcspr, SYS_GCSPR_EL0);
+
+ return 0;
+}
+
+#else /* ! CONFIG_ARM64_GCS */
+
+/* Turn any non-optimised out attempts to use these into a link error: */
+extern int preserve_gcs_context(void __user *ctx);
+extern int restore_gcs_context(struct user_ctxs *user);
+
+#endif /* ! CONFIG_ARM64_GCS */
+
+static int parse_user_sigframe(struct user_ctxs *user,
+ struct rt_sigframe __user *sf)
+{
+ struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
+ struct _aarch64_ctx __user *head;
+ char __user *base = (char __user *)&sc->__reserved;
+ size_t offset = 0;
+ size_t limit = sizeof(sc->__reserved);
+ bool have_extra_context = false;
+ char const __user *const sfp = (char const __user *)sf;
+
+ user->fpsimd = NULL;
+ user->sve = NULL;
+ user->tpidr2 = NULL;
+ user->za = NULL;
+ user->zt = NULL;
+ user->fpmr = NULL;
+ user->poe = NULL;
+ user->gcs = NULL;
+
+ if (!IS_ALIGNED((unsigned long)base, 16))
+ goto invalid;
+
+ while (1) {
+ int err = 0;
+ u32 magic, size;
+ char const __user *userp;
+ struct extra_context const __user *extra;
+ u64 extra_datap;
+ u32 extra_size;
+ struct _aarch64_ctx const __user *end;
+ u32 end_magic, end_size;
+
+ if (limit - offset < sizeof(*head))
+ goto invalid;
+
+ if (!IS_ALIGNED(offset, 16))
+ goto invalid;
+
+ head = (struct _aarch64_ctx __user *)(base + offset);
+ __get_user_error(magic, &head->magic, err);
+ __get_user_error(size, &head->size, err);
+ if (err)
+ return err;
+
+ if (limit - offset < size)
+ goto invalid;
+
+ switch (magic) {
+ case 0:
+ if (size)
+ goto invalid;
+
+ goto done;
+
+ case FPSIMD_MAGIC:
+ if (!system_supports_fpsimd())
+ goto invalid;
+ if (user->fpsimd)
+ goto invalid;
+
+ user->fpsimd = (struct fpsimd_context __user *)head;
+ user->fpsimd_size = size;
+ break;
+
+ case ESR_MAGIC:
+ /* ignore */
+ break;
+
+ case POE_MAGIC:
+ if (!system_supports_poe())
+ goto invalid;
+
+ if (user->poe)
+ goto invalid;
+
+ user->poe = (struct poe_context __user *)head;
+ user->poe_size = size;
+ break;
+
+ case SVE_MAGIC:
+ if (!system_supports_sve() && !system_supports_sme())
+ goto invalid;
+
+ if (user->sve)
+ goto invalid;
+
+ user->sve = (struct sve_context __user *)head;
+ user->sve_size = size;
+ break;
+
+ case TPIDR2_MAGIC:
+ if (!system_supports_tpidr2())
+ goto invalid;
+
+ if (user->tpidr2)
+ goto invalid;
+
+ user->tpidr2 = (struct tpidr2_context __user *)head;
+ user->tpidr2_size = size;
+ break;
+
+ case ZA_MAGIC:
+ if (!system_supports_sme())
+ goto invalid;
+
+ if (user->za)
+ goto invalid;
+
+ user->za = (struct za_context __user *)head;
+ user->za_size = size;
+ break;
+
+ case ZT_MAGIC:
+ if (!system_supports_sme2())
+ goto invalid;
+
+ if (user->zt)
+ goto invalid;
+
+ user->zt = (struct zt_context __user *)head;
+ user->zt_size = size;
+ break;
+
+ case FPMR_MAGIC:
+ if (!system_supports_fpmr())
+ goto invalid;
+
+ if (user->fpmr)
+ goto invalid;
+
+ user->fpmr = (struct fpmr_context __user *)head;
+ user->fpmr_size = size;
+ break;
+
+ case GCS_MAGIC:
+ if (!system_supports_gcs())
+ goto invalid;
+
+ if (user->gcs)
+ goto invalid;
+
+ user->gcs = (struct gcs_context __user *)head;
+ user->gcs_size = size;
+ break;
+
+ case EXTRA_MAGIC:
+ if (have_extra_context)
+ goto invalid;
+
+ if (size < sizeof(*extra))
+ goto invalid;
+
+ userp = (char const __user *)head;
+
+ extra = (struct extra_context const __user *)userp;
+ userp += size;
+
+ __get_user_error(extra_datap, &extra->datap, err);
+ __get_user_error(extra_size, &extra->size, err);
+ if (err)
+ return err;
+
+ /* Check for the dummy terminator in __reserved[]: */
+
+ if (limit - offset - size < TERMINATOR_SIZE)
+ goto invalid;
+
+ end = (struct _aarch64_ctx const __user *)userp;
+ userp += TERMINATOR_SIZE;
+
+ __get_user_error(end_magic, &end->magic, err);
+ __get_user_error(end_size, &end->size, err);
+ if (err)
+ return err;
+
+ if (end_magic || end_size)
+ goto invalid;
+
+ /* Prevent looping/repeated parsing of extra_context */
+ have_extra_context = true;
+
+ base = (__force void __user *)extra_datap;
+ if (!IS_ALIGNED((unsigned long)base, 16))
+ goto invalid;
+
+ if (!IS_ALIGNED(extra_size, 16))
+ goto invalid;
+
+ if (base != userp)
+ goto invalid;
+
+ /* Reject "unreasonably large" frames: */
+ if (extra_size > sfp + SIGFRAME_MAXSZ - userp)
+ goto invalid;
+
+ /*
+ * Ignore trailing terminator in __reserved[]
+ * and start parsing extra data:
+ */
+ offset = 0;
+ limit = extra_size;
+
+ if (!access_ok(base, limit))
+ goto invalid;
+
+ continue;
+
+ default:
+ goto invalid;
+ }
+
+ if (size < sizeof(*head))
+ goto invalid;
+
+ if (limit - offset < size)
+ goto invalid;
+
+ offset += size;
+ }
+
+done:
+ return 0;
+
+invalid:
+ return -EINVAL;
+}
+
static int restore_sigframe(struct pt_regs *regs,
- struct rt_sigframe __user *sf)
+ struct rt_sigframe __user *sf,
+ struct user_access_state *ua_state)
{
sigset_t set;
int i, err;
- struct aux_context __user *aux =
- (struct aux_context __user *)sf->uc.uc_mcontext.__reserved;
+ struct user_ctxs user;
err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
if (err == 0)
@@ -117,22 +986,105 @@ static int restore_sigframe(struct pt_regs *regs,
/*
* Avoid sys_rt_sigreturn() restarting.
*/
- regs->syscallno = ~0UL;
+ forget_syscall(regs);
- err |= !valid_user_regs(&regs->user_regs);
+ fpsimd_save_and_flush_current_state();
+ err |= !valid_user_regs(&regs->user_regs, current);
if (err == 0)
- err |= restore_fpsimd_context(&aux->fpsimd);
+ err = parse_user_sigframe(&user, sf);
+
+ if (err == 0 && system_supports_fpsimd()) {
+ if (!user.fpsimd)
+ return -EINVAL;
+
+ if (user.sve)
+ err = restore_sve_fpsimd_context(&user);
+ else
+ err = restore_fpsimd_context(&user);
+ }
+
+ if (err == 0 && system_supports_gcs() && user.gcs)
+ err = restore_gcs_context(&user);
+
+ if (err == 0 && system_supports_tpidr2() && user.tpidr2)
+ err = restore_tpidr2_context(&user);
+
+ if (err == 0 && system_supports_fpmr() && user.fpmr)
+ err = restore_fpmr_context(&user);
+
+ if (err == 0 && system_supports_sme() && user.za)
+ err = restore_za_context(&user);
+
+ if (err == 0 && system_supports_sme2() && user.zt)
+ err = restore_zt_context(&user);
+
+ if (err == 0 && system_supports_poe() && user.poe)
+ err = restore_poe_context(&user, ua_state);
return err;
}
-asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
+#ifdef CONFIG_ARM64_GCS
+static int gcs_restore_signal(void)
{
+ u64 gcspr_el0, cap;
+ int ret;
+
+ if (!system_supports_gcs())
+ return 0;
+
+ if (!(current->thread.gcs_el0_mode & PR_SHADOW_STACK_ENABLE))
+ return 0;
+
+ gcspr_el0 = read_sysreg_s(SYS_GCSPR_EL0);
+
+ /*
+ * Ensure that any changes to the GCS done via GCS operations
+ * are visible to the normal reads we do to validate the
+ * token.
+ */
+ gcsb_dsync();
+
+ /*
+ * GCSPR_EL0 should be pointing at a capped GCS, read the cap.
+ * We don't enforce that this is in a GCS page, if it is not
+ * then faults will be generated on GCS operations - the main
+ * concern is to protect GCS pages.
+ */
+ ret = copy_from_user(&cap, (unsigned long __user *)gcspr_el0,
+ sizeof(cap));
+ if (ret)
+ return -EFAULT;
+
+ /*
+ * Check that the cap is the actual GCS before replacing it.
+ */
+ if (cap != GCS_SIGNAL_CAP(gcspr_el0))
+ return -EINVAL;
+
+ /* Invalidate the token to prevent reuse */
+ put_user_gcs(0, (unsigned long __user *)gcspr_el0, &ret);
+ if (ret != 0)
+ return -EFAULT;
+
+ write_sysreg_s(gcspr_el0 + 8, SYS_GCSPR_EL0);
+
+ return 0;
+}
+
+#else
+static int gcs_restore_signal(void) { return 0; }
+#endif
+
+SYSCALL_DEFINE0(rt_sigreturn)
+{
+ struct pt_regs *regs = current_pt_regs();
struct rt_sigframe __user *frame;
+ struct user_access_state ua_state;
/* Always make any pending restarted system calls return -EINTR */
- current_thread_info()->restart_block.fn = do_no_restart_syscall;
+ current->restart_block.fn = do_no_restart_syscall;
/*
* Since we stacked the signal on a 128-bit boundary, then 'sp' should
@@ -143,36 +1095,143 @@ asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
frame = (struct rt_sigframe __user *)regs->sp;
- if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
+ if (!access_ok(frame, sizeof (*frame)))
goto badframe;
- if (restore_sigframe(regs, frame))
+ if (restore_sigframe(regs, frame, &ua_state))
+ goto badframe;
+
+ if (gcs_restore_signal())
goto badframe;
if (restore_altstack(&frame->uc.uc_stack))
goto badframe;
+ restore_user_access_state(&ua_state);
+
return regs->regs[0];
badframe:
- if (show_unhandled_signals)
- pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
- current->comm, task_pid_nr(current), __func__,
- regs->pc, regs->sp);
- force_sig(SIGSEGV, current);
+ arm64_notify_segfault(regs->sp);
return 0;
}
-static int setup_sigframe(struct rt_sigframe __user *sf,
- struct pt_regs *regs, sigset_t *set)
+/*
+ * Determine the layout of optional records in the signal frame
+ *
+ * add_all: if true, lays out the biggest possible signal frame for
+ * this task; otherwise, generates a layout for the current state
+ * of the task.
+ */
+static int setup_sigframe_layout(struct rt_sigframe_user_layout *user,
+ bool add_all)
+{
+ int err;
+
+ if (system_supports_fpsimd()) {
+ err = sigframe_alloc(user, &user->fpsimd_offset,
+ sizeof(struct fpsimd_context));
+ if (err)
+ return err;
+ }
+
+ /* fault information, if valid */
+ if (add_all || current->thread.fault_code) {
+ err = sigframe_alloc(user, &user->esr_offset,
+ sizeof(struct esr_context));
+ if (err)
+ return err;
+ }
+
+#ifdef CONFIG_ARM64_GCS
+ if (system_supports_gcs() && (add_all || current->thread.gcspr_el0)) {
+ err = sigframe_alloc(user, &user->gcs_offset,
+ sizeof(struct gcs_context));
+ if (err)
+ return err;
+ }
+#endif
+
+ if (system_supports_sve() || system_supports_sme()) {
+ unsigned int vq = 0;
+
+ if (add_all || current->thread.fp_type == FP_STATE_SVE ||
+ thread_sm_enabled(&current->thread)) {
+ int vl = max(sve_max_vl(), sme_max_vl());
+
+ if (!add_all)
+ vl = thread_get_cur_vl(&current->thread);
+
+ vq = sve_vq_from_vl(vl);
+ }
+
+ err = sigframe_alloc(user, &user->sve_offset,
+ SVE_SIG_CONTEXT_SIZE(vq));
+ if (err)
+ return err;
+ }
+
+ if (system_supports_tpidr2()) {
+ err = sigframe_alloc(user, &user->tpidr2_offset,
+ sizeof(struct tpidr2_context));
+ if (err)
+ return err;
+ }
+
+ if (system_supports_sme()) {
+ unsigned int vl;
+ unsigned int vq = 0;
+
+ if (add_all)
+ vl = sme_max_vl();
+ else
+ vl = task_get_sme_vl(current);
+
+ if (thread_za_enabled(&current->thread))
+ vq = sve_vq_from_vl(vl);
+
+ err = sigframe_alloc(user, &user->za_offset,
+ ZA_SIG_CONTEXT_SIZE(vq));
+ if (err)
+ return err;
+ }
+
+ if (system_supports_sme2()) {
+ if (add_all || thread_za_enabled(&current->thread)) {
+ err = sigframe_alloc(user, &user->zt_offset,
+ ZT_SIG_CONTEXT_SIZE(1));
+ if (err)
+ return err;
+ }
+ }
+
+ if (system_supports_fpmr()) {
+ err = sigframe_alloc(user, &user->fpmr_offset,
+ sizeof(struct fpmr_context));
+ if (err)
+ return err;
+ }
+
+ if (system_supports_poe()) {
+ err = sigframe_alloc(user, &user->poe_offset,
+ sizeof(struct poe_context));
+ if (err)
+ return err;
+ }
+
+ return sigframe_alloc_end(user);
+}
+
+static int setup_sigframe(struct rt_sigframe_user_layout *user,
+ struct pt_regs *regs, sigset_t *set,
+ const struct user_access_state *ua_state)
{
int i, err = 0;
- struct aux_context __user *aux =
- (struct aux_context __user *)sf->uc.uc_mcontext.__reserved;
+ struct rt_sigframe __user *sf = user->sigframe;
/* set up the stack frame for unwinding */
- __put_user_error(regs->regs[29], &sf->fp, err);
- __put_user_error(regs->regs[30], &sf->lr, err);
+ __put_user_error(regs->regs[29], &user->next_frame->fp, err);
+ __put_user_error(regs->regs[30], &user->next_frame->lr, err);
for (i = 0; i < 31; i++)
__put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
@@ -185,83 +1244,286 @@ static int setup_sigframe(struct rt_sigframe __user *sf,
err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
- if (err == 0)
- err |= preserve_fpsimd_context(&aux->fpsimd);
+ if (err == 0 && system_supports_fpsimd()) {
+ struct fpsimd_context __user *fpsimd_ctx =
+ apply_user_offset(user, user->fpsimd_offset);
+ err |= preserve_fpsimd_context(fpsimd_ctx);
+ }
+
+ /* fault information, if valid */
+ if (err == 0 && user->esr_offset) {
+ struct esr_context __user *esr_ctx =
+ apply_user_offset(user, user->esr_offset);
+
+ __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
+ __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
+ __put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
+ }
+
+ if (system_supports_gcs() && err == 0 && user->gcs_offset) {
+ struct gcs_context __user *gcs_ctx =
+ apply_user_offset(user, user->gcs_offset);
+ err |= preserve_gcs_context(gcs_ctx);
+ }
+
+ /* Scalable Vector Extension state (including streaming), if present */
+ if ((system_supports_sve() || system_supports_sme()) &&
+ err == 0 && user->sve_offset) {
+ struct sve_context __user *sve_ctx =
+ apply_user_offset(user, user->sve_offset);
+ err |= preserve_sve_context(sve_ctx);
+ }
+
+ /* TPIDR2 if supported */
+ if (system_supports_tpidr2() && err == 0) {
+ struct tpidr2_context __user *tpidr2_ctx =
+ apply_user_offset(user, user->tpidr2_offset);
+ err |= preserve_tpidr2_context(tpidr2_ctx);
+ }
+
+ /* FPMR if supported */
+ if (system_supports_fpmr() && err == 0) {
+ struct fpmr_context __user *fpmr_ctx =
+ apply_user_offset(user, user->fpmr_offset);
+ err |= preserve_fpmr_context(fpmr_ctx);
+ }
+
+ if (system_supports_poe() && err == 0) {
+ struct poe_context __user *poe_ctx =
+ apply_user_offset(user, user->poe_offset);
+
+ err |= preserve_poe_context(poe_ctx, ua_state);
+ }
+
+ /* ZA state if present */
+ if (system_supports_sme() && err == 0 && user->za_offset) {
+ struct za_context __user *za_ctx =
+ apply_user_offset(user, user->za_offset);
+ err |= preserve_za_context(za_ctx);
+ }
+
+ /* ZT state if present */
+ if (system_supports_sme2() && err == 0 && user->zt_offset) {
+ struct zt_context __user *zt_ctx =
+ apply_user_offset(user, user->zt_offset);
+ err |= preserve_zt_context(zt_ctx);
+ }
+
+ if (err == 0 && user->extra_offset) {
+ char __user *sfp = (char __user *)user->sigframe;
+ char __user *userp =
+ apply_user_offset(user, user->extra_offset);
+
+ struct extra_context __user *extra;
+ struct _aarch64_ctx __user *end;
+ u64 extra_datap;
+ u32 extra_size;
+
+ extra = (struct extra_context __user *)userp;
+ userp += EXTRA_CONTEXT_SIZE;
+
+ end = (struct _aarch64_ctx __user *)userp;
+ userp += TERMINATOR_SIZE;
+
+ /*
+ * extra_datap is just written to the signal frame.
+ * The value gets cast back to a void __user *
+ * during sigreturn.
+ */
+ extra_datap = (__force u64)userp;
+ extra_size = sfp + round_up(user->size, 16) - userp;
+
+ __put_user_error(EXTRA_MAGIC, &extra->head.magic, err);
+ __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err);
+ __put_user_error(extra_datap, &extra->datap, err);
+ __put_user_error(extra_size, &extra->size, err);
+
+ /* Add the terminator */
+ __put_user_error(0, &end->magic, err);
+ __put_user_error(0, &end->size, err);
+ }
/* set the "end" magic */
- __put_user_error(0, &aux->end.magic, err);
- __put_user_error(0, &aux->end.size, err);
+ if (err == 0) {
+ struct _aarch64_ctx __user *end =
+ apply_user_offset(user, user->end_offset);
+
+ __put_user_error(0, &end->magic, err);
+ __put_user_error(0, &end->size, err);
+ }
return err;
}
-static struct rt_sigframe __user *get_sigframe(struct k_sigaction *ka,
- struct pt_regs *regs)
+static int get_sigframe(struct rt_sigframe_user_layout *user,
+ struct ksignal *ksig, struct pt_regs *regs)
{
unsigned long sp, sp_top;
- struct rt_sigframe __user *frame;
+ int err;
+
+ init_user_layout(user);
+ err = setup_sigframe_layout(user, false);
+ if (err)
+ return err;
- sp = sp_top = regs->sp;
+ sp = sp_top = sigsp(regs->sp, ksig);
+
+ sp = round_down(sp - sizeof(struct frame_record), 16);
+ user->next_frame = (struct frame_record __user *)sp;
+
+ sp = round_down(sp, 16) - sigframe_size(user);
+ user->sigframe = (struct rt_sigframe __user *)sp;
/*
- * This is the X/Open sanctioned signal stack switching.
+ * Check that we can actually write to the signal frame.
*/
- if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
- sp = sp_top = current->sas_ss_sp + current->sas_ss_size;
+ if (!access_ok(user->sigframe, sp_top - sp))
+ return -EFAULT;
- sp = (sp - sizeof(struct rt_sigframe)) & ~15;
- frame = (struct rt_sigframe __user *)sp;
+ return 0;
+}
+
+#ifdef CONFIG_ARM64_GCS
+
+static int gcs_signal_entry(__sigrestore_t sigtramp, struct ksignal *ksig)
+{
+ u64 gcspr_el0;
+ int ret = 0;
+
+ if (!system_supports_gcs())
+ return 0;
+
+ if (!task_gcs_el0_enabled(current))
+ return 0;
/*
- * Check that we can actually write to the signal frame.
+ * We are entering a signal handler, current register state is
+ * active.
*/
- if (!access_ok(VERIFY_WRITE, frame, sp_top - sp))
- frame = NULL;
+ gcspr_el0 = read_sysreg_s(SYS_GCSPR_EL0);
- return frame;
+ /*
+ * Push a cap and the GCS entry for the trampoline onto the GCS.
+ */
+ put_user_gcs((unsigned long)sigtramp,
+ (unsigned long __user *)(gcspr_el0 - 16), &ret);
+ put_user_gcs(GCS_SIGNAL_CAP(gcspr_el0 - 8),
+ (unsigned long __user *)(gcspr_el0 - 8), &ret);
+ if (ret != 0)
+ return ret;
+
+ gcspr_el0 -= 16;
+ write_sysreg_s(gcspr_el0, SYS_GCSPR_EL0);
+
+ return 0;
}
+#else
-static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
- void __user *frame, int usig)
+static int gcs_signal_entry(__sigrestore_t sigtramp, struct ksignal *ksig)
{
- __sigrestore_t sigtramp;
+ return 0;
+}
- regs->regs[0] = usig;
- regs->sp = (unsigned long)frame;
- regs->regs[29] = regs->sp + offsetof(struct rt_sigframe, fp);
- regs->pc = (unsigned long)ka->sa.sa_handler;
+#endif
+
+static int setup_return(struct pt_regs *regs, struct ksignal *ksig,
+ struct rt_sigframe_user_layout *user, int usig)
+{
+ __sigrestore_t sigtramp;
+ int err;
- if (ka->sa.sa_flags & SA_RESTORER)
- sigtramp = ka->sa.sa_restorer;
+ if (ksig->ka.sa.sa_flags & SA_RESTORER)
+ sigtramp = ksig->ka.sa.sa_restorer;
else
sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
+ err = gcs_signal_entry(sigtramp, ksig);
+ if (err)
+ return err;
+
+ /*
+ * We must not fail from this point onwards. We are going to update
+ * registers, including SP, in order to invoke the signal handler. If
+ * we failed and attempted to deliver a nested SIGSEGV to a handler
+ * after that point, the subsequent sigreturn would end up restoring
+ * the (partial) state for the original signal handler.
+ */
+
+ regs->regs[0] = usig;
+ if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
+ regs->regs[1] = (unsigned long)&user->sigframe->info;
+ regs->regs[2] = (unsigned long)&user->sigframe->uc;
+ }
+ regs->sp = (unsigned long)user->sigframe;
+ regs->regs[29] = (unsigned long)&user->next_frame->fp;
regs->regs[30] = (unsigned long)sigtramp;
+ regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
+
+ /*
+ * Signal delivery is a (wacky) indirect function call in
+ * userspace, so simulate the same setting of BTYPE as a BLR
+ * <register containing the signal handler entry point>.
+ * Signal delivery to a location in a PROT_BTI guarded page
+ * that is not a function entry point will now trigger a
+ * SIGILL in userspace.
+ *
+ * If the signal handler entry point is not in a PROT_BTI
+ * guarded page, this is harmless.
+ */
+ if (system_supports_bti()) {
+ regs->pstate &= ~PSR_BTYPE_MASK;
+ regs->pstate |= PSR_BTYPE_C;
+ }
+
+ /* TCO (Tag Check Override) always cleared for signal handlers */
+ regs->pstate &= ~PSR_TCO_BIT;
+
+ /* Signal handlers are invoked with ZA and streaming mode disabled */
+ if (system_supports_sme()) {
+ task_smstop_sm(current);
+ current->thread.svcr &= ~SVCR_ZA_MASK;
+ write_sysreg_s(0, SYS_TPIDR2_EL0);
+ }
+
+ return 0;
}
-static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
- sigset_t *set, struct pt_regs *regs)
+static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
+ struct pt_regs *regs)
{
+ struct rt_sigframe_user_layout user;
struct rt_sigframe __user *frame;
+ struct user_access_state ua_state;
int err = 0;
- frame = get_sigframe(ka, regs);
- if (!frame)
+ fpsimd_save_and_flush_current_state();
+
+ if (get_sigframe(&user, ksig, regs))
return 1;
+ save_reset_user_access_state(&ua_state);
+ frame = user.sigframe;
+
__put_user_error(0, &frame->uc.uc_flags, err);
__put_user_error(NULL, &frame->uc.uc_link, err);
err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
- err |= setup_sigframe(frame, regs, set);
- if (err == 0) {
- setup_return(regs, ka, frame, usig);
- if (ka->sa.sa_flags & SA_SIGINFO) {
- err |= copy_siginfo_to_user(&frame->info, info);
- regs->regs[1] = (unsigned long)&frame->info;
- regs->regs[2] = (unsigned long)&frame->uc;
- }
- }
+ err |= setup_sigframe(&user, regs, set, &ua_state);
+ if (ksig->ka.sa.sa_flags & SA_SIGINFO)
+ err |= copy_siginfo_to_user(&frame->info, &ksig->info);
+
+ if (err == 0)
+ err = setup_return(regs, ksig, &user, usig);
+
+ /*
+ * We must not fail if setup_return() succeeded - see comment at the
+ * beginning of setup_return().
+ */
+
+ if (err == 0)
+ set_handler_user_access_state();
+ else
+ restore_user_access_state(&ua_state);
return err;
}
@@ -277,51 +1539,33 @@ static void setup_restart_syscall(struct pt_regs *regs)
/*
* OK, we're invoking a handler
*/
-static void handle_signal(unsigned long sig, struct k_sigaction *ka,
- siginfo_t *info, struct pt_regs *regs)
+static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
- struct thread_info *thread = current_thread_info();
- struct task_struct *tsk = current;
sigset_t *oldset = sigmask_to_save();
- int usig = sig;
+ int usig = ksig->sig;
int ret;
- /*
- * translate the signal
- */
- if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap)
- usig = thread->exec_domain->signal_invmap[usig];
+ rseq_signal_deliver(ksig, regs);
/*
* Set up the stack frame
*/
if (is_compat_task()) {
- if (ka->sa.sa_flags & SA_SIGINFO)
- ret = compat_setup_rt_frame(usig, ka, info, oldset,
- regs);
+ if (ksig->ka.sa.sa_flags & SA_SIGINFO)
+ ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
else
- ret = compat_setup_frame(usig, ka, oldset, regs);
+ ret = compat_setup_frame(usig, ksig, oldset, regs);
} else {
- ret = setup_rt_frame(usig, ka, info, oldset, regs);
+ ret = setup_rt_frame(usig, ksig, oldset, regs);
}
/*
* Check that the resulting registers are actually sane.
*/
- ret |= !valid_user_regs(&regs->user_regs);
+ ret |= !valid_user_regs(&regs->user_regs, current);
- if (ret != 0) {
- force_sigsegv(sig, tsk);
- return;
- }
-
- /*
- * Fast forward the stepping logic so we step into the signal
- * handler.
- */
- user_fastforward_single_step(tsk);
-
- signal_delivered(sig, info, ka, regs, 0);
+ /* Step into the signal handler if we are stepping */
+ signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
}
/*
@@ -333,18 +1577,17 @@ static void handle_signal(unsigned long sig, struct k_sigaction *ka,
* the kernel can handle, and then we build all the user-level signal handling
* stack-frames in one go after that.
*/
-static void do_signal(struct pt_regs *regs)
+void arch_do_signal_or_restart(struct pt_regs *regs)
{
unsigned long continue_addr = 0, restart_addr = 0;
- struct k_sigaction ka;
- siginfo_t info;
- int signr, retval = 0;
- int syscall = (int)regs->syscallno;
+ int retval = 0;
+ struct ksignal ksig;
+ bool syscall = in_syscall(regs);
/*
* If we were from a system call, check for system call restarting...
*/
- if (syscall >= 0) {
+ if (syscall) {
continue_addr = regs->pc;
restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
retval = regs->regs[0];
@@ -352,7 +1595,7 @@ static void do_signal(struct pt_regs *regs)
/*
* Avoid additional syscall restarting via ret_to_user.
*/
- regs->syscallno = ~0UL;
+ forget_syscall(regs);
/*
* Prepare for system call restart. We do this here so that a
@@ -373,8 +1616,7 @@ static void do_signal(struct pt_regs *regs)
* Get the signal to deliver. When running under ptrace, at this point
* the debugger may change all of our registers.
*/
- signr = get_signal_to_deliver(&info, &ka, regs, NULL);
- if (signr > 0) {
+ if (get_signal(&ksig)) {
/*
* Depending on the signal settings, we may need to revert the
* decision to restart the system call, but skip this if a
@@ -384,12 +1626,12 @@ static void do_signal(struct pt_regs *regs)
(retval == -ERESTARTNOHAND ||
retval == -ERESTART_RESTARTBLOCK ||
(retval == -ERESTARTSYS &&
- !(ka.sa.sa_flags & SA_RESTART)))) {
- regs->regs[0] = -EINTR;
+ !(ksig.ka.sa.sa_flags & SA_RESTART)))) {
+ syscall_set_return_value(current, regs, -EINTR, 0);
regs->pc = continue_addr;
}
- handle_signal(signr, &ka, &info, regs);
+ handle_signal(&ksig, regs);
return;
}
@@ -397,7 +1639,7 @@ static void do_signal(struct pt_regs *regs)
* Handle restarting a different system call. As above, if a debugger
* has chosen to restart at a different PC, ignore the restart.
*/
- if (syscall >= 0 && regs->pc == restart_addr) {
+ if (syscall && regs->pc == restart_addr) {
if (retval == -ERESTART_RESTARTBLOCK)
setup_restart_syscall(regs);
user_rewind_single_step(current);
@@ -406,14 +1648,67 @@ static void do_signal(struct pt_regs *regs)
restore_saved_sigmask();
}
-asmlinkage void do_notify_resume(struct pt_regs *regs,
- unsigned int thread_flags)
+unsigned long __ro_after_init signal_minsigstksz;
+
+/*
+ * Determine the stack space required for guaranteed signal devliery.
+ * This function is used to populate AT_MINSIGSTKSZ at process startup.
+ * cpufeatures setup is assumed to be complete.
+ */
+void __init minsigstksz_setup(void)
{
- if (thread_flags & _TIF_SIGPENDING)
- do_signal(regs);
+ struct rt_sigframe_user_layout user;
- if (thread_flags & _TIF_NOTIFY_RESUME) {
- clear_thread_flag(TIF_NOTIFY_RESUME);
- tracehook_notify_resume(regs);
- }
+ init_user_layout(&user);
+
+ /*
+ * If this fails, SIGFRAME_MAXSZ needs to be enlarged. It won't
+ * be big enough, but it's our best guess:
+ */
+ if (WARN_ON(setup_sigframe_layout(&user, true)))
+ return;
+
+ signal_minsigstksz = sigframe_size(&user) +
+ round_up(sizeof(struct frame_record), 16) +
+ 16; /* max alignment padding */
}
+
+/*
+ * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
+ * changes likely come with new fields that should be added below.
+ */
+static_assert(NSIGILL == 11);
+static_assert(NSIGFPE == 15);
+static_assert(NSIGSEGV == 10);
+static_assert(NSIGBUS == 5);
+static_assert(NSIGTRAP == 6);
+static_assert(NSIGCHLD == 6);
+static_assert(NSIGSYS == 2);
+static_assert(sizeof(siginfo_t) == 128);
+static_assert(__alignof__(siginfo_t) == 8);
+static_assert(offsetof(siginfo_t, si_signo) == 0x00);
+static_assert(offsetof(siginfo_t, si_errno) == 0x04);
+static_assert(offsetof(siginfo_t, si_code) == 0x08);
+static_assert(offsetof(siginfo_t, si_pid) == 0x10);
+static_assert(offsetof(siginfo_t, si_uid) == 0x14);
+static_assert(offsetof(siginfo_t, si_tid) == 0x10);
+static_assert(offsetof(siginfo_t, si_overrun) == 0x14);
+static_assert(offsetof(siginfo_t, si_status) == 0x18);
+static_assert(offsetof(siginfo_t, si_utime) == 0x20);
+static_assert(offsetof(siginfo_t, si_stime) == 0x28);
+static_assert(offsetof(siginfo_t, si_value) == 0x18);
+static_assert(offsetof(siginfo_t, si_int) == 0x18);
+static_assert(offsetof(siginfo_t, si_ptr) == 0x18);
+static_assert(offsetof(siginfo_t, si_addr) == 0x10);
+static_assert(offsetof(siginfo_t, si_addr_lsb) == 0x18);
+static_assert(offsetof(siginfo_t, si_lower) == 0x20);
+static_assert(offsetof(siginfo_t, si_upper) == 0x28);
+static_assert(offsetof(siginfo_t, si_pkey) == 0x20);
+static_assert(offsetof(siginfo_t, si_perf_data) == 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type) == 0x20);
+static_assert(offsetof(siginfo_t, si_perf_flags) == 0x24);
+static_assert(offsetof(siginfo_t, si_band) == 0x10);
+static_assert(offsetof(siginfo_t, si_fd) == 0x18);
+static_assert(offsetof(siginfo_t, si_call_addr) == 0x10);
+static_assert(offsetof(siginfo_t, si_syscall) == 0x18);
+static_assert(offsetof(siginfo_t, si_arch) == 0x1c);
generated by cgit (git 2.34.1) at 2025-12-25 04:59:30 +0000