[PATCH v3 5/5] testsuite/switchtest: Add support for Dovetail >= 6.19

The background for this reworking is a recent change to Linux in 6.19:

commit 4fa617cc6851 ("arm64/fpsimd: Allocate kernel mode FP/SIMD
		     buffers on the stack")

expects all (non-preemtable) users to provide a buffer that is used
in case the calling task is scheduled out. NULL is only allowed when
preemption is disabled.

preempt_disable() has no impact on OOB tasks, so when an OOB task
is scheduled out the fpsimd code tries to save the FPU regs to NULL,
which (obviously) triggered a fault.

To be able to provide a struct user_fpsimd_state located on the
stack  the signature of fp_linux_begin() on all architectures has
been updated.

There is a new arch dependent struct now: cobalt_arch_fp_state.
Arm64 will wrap the FPU state (struct user_fpsimd_state) there,
all remaining archs will implement an empty (and unused) type.

Signed-off-by: Florian Bezdeka <[email protected]>
---
 kernel/cobalt/arch/arm/include/asm/xenomai/fptest.h   |  6 ++++--
 kernel/cobalt/arch/arm64/include/asm/xenomai/fptest.h | 16 +++++++++++-----
 kernel/cobalt/arch/x86/include/asm/xenomai/fptest.h   |  9 ++++++---
 kernel/cobalt/include/asm-generic/xenomai/wrappers.h  |  7 +++++++
 kernel/drivers/testing/switchtest.c                   | 18 +++++++++++++-----
 5 files changed, 41 insertions(+), 15 deletions(-)

diff --git a/kernel/cobalt/arch/arm/include/asm/xenomai/fptest.h b/kernel/cobalt/arch/arm/include/asm/xenomai/fptest.h
index fc177fcb53bd259011a4a65f889c236f7c8e115e..3b80fa8461d44e3cf224dcba3d0bd7255d302732 100644
--- a/kernel/cobalt/arch/arm/include/asm/xenomai/fptest.h
+++ b/kernel/cobalt/arch/arm/include/asm/xenomai/fptest.h
@@ -30,12 +30,14 @@
 
 #include <asm/xenomai/uapi/fptest.h>
 
-static inline int fp_linux_begin(void)
+struct cobalt_arch_fp_state {};
+
+static inline int fp_linux_begin(struct cobalt_arch_fp_state *state)
 {
 	return -ENOSYS;
 }
 
-static inline void fp_linux_end(void)
+static inline void fp_linux_end(struct cobalt_arch_fp_state *state)
 {
 }
 
diff --git a/kernel/cobalt/arch/arm64/include/asm/xenomai/fptest.h b/kernel/cobalt/arch/arm64/include/asm/xenomai/fptest.h
index 520cd38519db66ad25baecedd183d56f92895539..e1ff046e1c9a99990cc93bcb7f3aa600186bfb36 100644
--- a/kernel/cobalt/arch/arm64/include/asm/xenomai/fptest.h
+++ b/kernel/cobalt/arch/arm64/include/asm/xenomai/fptest.h
@@ -7,22 +7,28 @@
 #ifndef _COBALT_ARM64_FPTEST_H
 #define _COBALT_ARM64_FPTEST_H
 
-#include <asm/xenomai/uapi/fptest.h>
 #include <asm/hwcap.h>
 #include <asm/neon.h>
 
+#include <asm/xenomai/uapi/fptest.h>
+#include <asm-generic/xenomai/wrappers.h>
+
 #define have_fp (ELF_HWCAP & HWCAP_FP)
 
-static inline int fp_linux_begin(void)
+struct cobalt_arch_fp_state {
+	struct user_fpsimd_state state;
+};
+
+static inline int fp_linux_begin(struct cobalt_arch_fp_state *state)
 {
-	kernel_neon_begin();
+	kernel_neon_begin(&state->state);
 
 	return 0;
 }
 
-static inline void fp_linux_end(void)
+static inline void fp_linux_end(struct cobalt_arch_fp_state *state)
 {
-	kernel_neon_end();
+	kernel_neon_end(&state->state);
 }
 
 static inline int fp_detect(void)
diff --git a/kernel/cobalt/arch/x86/include/asm/xenomai/fptest.h b/kernel/cobalt/arch/x86/include/asm/xenomai/fptest.h
index 55818f853c2407eef40f3d1d9a1336bfa7605512..de6a931077fc7ff6aca6f8a27423e31d64bace0d 100644
--- a/kernel/cobalt/arch/x86/include/asm/xenomai/fptest.h
+++ b/kernel/cobalt/arch/x86/include/asm/xenomai/fptest.h
@@ -19,12 +19,15 @@
 #ifndef _COBALT_X86_ASM_FPTEST_H
 #define _COBALT_X86_ASM_FPTEST_H
 
-#include <linux/errno.h>
+#include <asm/fpu/api.h>
+
 #include <asm/processor.h>
 #include <asm/xenomai/wrappers.h>
 #include <asm/xenomai/uapi/fptest.h>
 
-static inline int fp_linux_begin(void)
+struct cobalt_arch_fp_state {};
+
+static inline int fp_linux_begin(struct cobalt_arch_fp_state *state)
 {
 	kernel_fpu_begin();
 	/*
@@ -38,7 +41,7 @@ static inline int fp_linux_begin(void)
 	return true;
 }
 
-static inline void fp_linux_end(void)
+static inline void fp_linux_end(struct cobalt_arch_fp_state *state)
 {
 	kernel_fpu_end();
 }
diff --git a/kernel/cobalt/include/asm-generic/xenomai/wrappers.h b/kernel/cobalt/include/asm-generic/xenomai/wrappers.h
index baf54dcfe7bb5071a1abea48bd87f471eb938297..27e641fa7f9178229e0616e4de64b0e267910915 100644
--- a/kernel/cobalt/include/asm-generic/xenomai/wrappers.h
+++ b/kernel/cobalt/include/asm-generic/xenomai/wrappers.h
@@ -84,4 +84,11 @@
 	})
 #endif
 
+#ifdef CONFIG_ARM64
+#if LINUX_VERSION_CODE < KERNEL_VERSION(6,19,0)
+#define kernel_neon_begin(fpu_preempt_buffer)	kernel_neon_begin()
+#define kernel_neon_end(fpu_preempt_buffer)	kernel_neon_end()
+#endif
+#endif
+
 #endif /* _COBALT_ASM_GENERIC_WRAPPERS_H */
diff --git a/kernel/drivers/testing/switchtest.c b/kernel/drivers/testing/switchtest.c
index f8f6c892076bba729d5d4b536288574df431e344..bb9c3dcae36f412562b78713bb10260d764dfd40 100644
--- a/kernel/drivers/testing/switchtest.c
+++ b/kernel/drivers/testing/switchtest.c
@@ -15,16 +15,23 @@
  * along with Xenomai; if not, write to the Free Software Foundation,
  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
+
 #include <linux/module.h>
 #include <linux/vmalloc.h>
 #include <linux/semaphore.h>
+
+/*
+ * Needs to be the first non-Linux include, wrappers.h for older kernels
+ * involved on arm64 and further Linux headers included at the top of fptest.h
+ */
+#include <asm/xenomai/fptest.h>
+
 #include <cobalt/kernel/sched.h>
 #include <cobalt/kernel/synch.h>
 #include <cobalt/kernel/thread.h>
 #include <cobalt/kernel/trace.h>
 #include <rtdm/testing.h>
 #include <rtdm/driver.h>
-#include <asm/xenomai/fptest.h>
 
 MODULE_DESCRIPTION("Cobalt context switch test helper");
 MODULE_AUTHOR("Gilles Chanteperdrix <[email protected]>");
@@ -236,6 +243,7 @@ static int rtswitch_to_nrt(struct rtswitch_context *ctx,
 			   unsigned int from_idx,
 			   unsigned int to_idx)
 {
+	struct cobalt_arch_fp_state state;
 	struct rtswitch_task *from, *to;
 	unsigned int expected, fp_val;
 	int fp_check;
@@ -276,7 +284,7 @@ static int rtswitch_to_nrt(struct rtswitch_context *ctx,
 
 		case RTSWITCH_RT:
 
-			if (!fp_check || fp_linux_begin() < 0) {
+			if (!fp_check || fp_linux_begin(&state) < 0) {
 				fp_check = 0;
 				goto signal_nofp;
 			}
@@ -287,7 +295,7 @@ static int rtswitch_to_nrt(struct rtswitch_context *ctx,
 			fp_regs_set(fp_features, expected);
 			rtdm_event_signal(&to->rt_synch);
 			fp_val = fp_regs_check(fp_features, expected, report);
-			fp_linux_end();
+			fp_linux_end(&state);
 
 			if(down_interruptible(&from->nrt_synch))
 				return -EINTR;
@@ -308,11 +316,11 @@ static int rtswitch_to_nrt(struct rtswitch_context *ctx,
 				(ctx->switches_count % 4000000) * 1000;
 			barrier();
 
-			fp_linux_begin();
+			fp_linux_begin(&state);
 			fp_regs_set(fp_features, expected);
 			rtdm_event_signal(&to->rt_synch);
 			fp_val = fp_regs_check(fp_features, expected, report);
-			fp_linux_end();
+			fp_linux_end(&state);
 
 			if (down_interruptible(&from->nrt_synch))
 				return -EINTR;

-- 
2.53.0