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 --- arch/arm64/include/uapi/asm/sigcontext.h | 8 +++++ arch/arm64/kernel/signal.c | 59 ++++++++++++++++++++++++++++++++ 2 files changed, 67 insertions(+)

diff --git a/arch/arm64/include/uapi/asm/sigcontext.h b/arch/arm64/include/uapi/asm/sigcontext.h index 9525041e4a14..4b4398d7fb2d 100644 --- 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 e0d09bf5b01b..5fe45c7c5e4f 100644 --- 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 =

Ensure that we get signal context for TPIDR2 if and only if SME is present on the system. Since TPIDR2 is owned by libc we merely validate that the value is whatever it was set to, this isn't ideal since it's likely to just be the default of 0 with current systems but it avoids future false positives.

Signed-off-by: Mark Brown broonie@kernel.org --- tools/testing/selftests/arm64/signal/.gitignore | 1 + .../arm64/signal/testcases/tpidr2_siginfo.c | 90 ++++++++++++++++++++++ 2 files changed, 91 insertions(+)

diff --git a/tools/testing/selftests/arm64/signal/.gitignore b/tools/testing/selftests/arm64/signal/.gitignore index e8d2b57f73ec..e1b6c4d961b5 100644 --- a/tools/testing/selftests/arm64/signal/.gitignore +++ b/tools/testing/selftests/arm64/signal/.gitignore @@ -4,5 +4,6 @@ fake_sigreturn_* sme_* ssve_* sve_* +tpidr2_siginfo za_* !*.[ch] diff --git a/tools/testing/selftests/arm64/signal/testcases/tpidr2_siginfo.c b/tools/testing/selftests/arm64/signal/testcases/tpidr2_siginfo.c new file mode 100644 index 000000000000..6a2c82bf7ead --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/tpidr2_siginfo.c @@ -0,0 +1,90 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2022 ARM Limited + * + * Verify that the TPIDR2 register context in signal frames is set up as + * expected. + */ + +#include <signal.h> +#include <ucontext.h> +#include <sys/auxv.h> +#include <sys/prctl.h> +#include <unistd.h> +#include <asm/sigcontext.h> + +#include "test_signals_utils.h" +#include "testcases.h" + +static union { + ucontext_t uc; + char buf[1024 * 128]; +} context; + +#define SYS_TPIDR2 "S3_3_C13_C0_5" + +static uint64_t get_tpidr2(void) +{ + uint64_t val; + + asm volatile ( + "mrs %0, " SYS_TPIDR2 "\n" + : "=r"(val) + : + : "cc"); + + return val; +} + +int tpidr2_present(struct tdescr *td, siginfo_t *si, ucontext_t *uc) +{ + struct _aarch64_ctx *head = GET_BUF_RESV_HEAD(context); + struct tpidr2_context *tpidr2_ctx; + size_t offset; + bool in_sigframe; + bool have_sme; + __u64 orig_tpidr2; + + have_sme = getauxval(AT_HWCAP2) & HWCAP2_SME; + if (have_sme) + orig_tpidr2 = get_tpidr2(); + + if (!get_current_context(td, &context.uc, sizeof(context))) + return 1; + + tpidr2_ctx = (struct tpidr2_context *) + get_header(head, TPIDR2_MAGIC, td->live_sz, &offset); + + in_sigframe = tpidr2_ctx != NULL; + + fprintf(stderr, "TPIDR2 sigframe %s on system %s SME\n", + in_sigframe ? "present" : "absent", + have_sme ? "with" : "without"); + + td->pass = (in_sigframe == have_sme); + + /* + * Check that the value we read back was the one present at + * the time that the signal was triggered. TPIDR2 is owned by + * libc so we can't safely choose the value and it is possible + * that we may need to revisit this in future if something + * starts deciding to set a new TPIDR2 between us reading and + * the signal. + */ + if (have_sme && tpidr2_ctx) { + if (tpidr2_ctx->tpidr2 != orig_tpidr2) { + fprintf(stderr, "TPIDR2 in frame is %llx, was %llx\n", + tpidr2_ctx->tpidr2, orig_tpidr2); + td->pass = false; + } + } + + return 0; +} + +struct tdescr tde = { + .name = "TPIDR2", + .descr = "Validate that TPIDR2 is present as expected", + .timeout = 3, + .run = tpidr2_present, +};