Merge tag 'alpha-for-v7.1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/lindholm/alpha

Pull alpha updates from Magnus Lindholm:
 "One fix to silence pgprot_modify() compiler warnings, and one patch
  adding SECCOMP/SECCOMP_FILTER support together with the syscall and
  ptrace fixes needed for it"

* tag 'alpha-for-v7.1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/lindholm/alpha:
  alpha: Define pgprot_modify to silence tautological comparison warnings
  alpha: add support for SECCOMP and SECCOMP_FILTER

4 files changed, 128 insertions, 2 deletions

diff --git a/arch/alpha/include/asm/pgtable.h b/arch/alpha/include/asm/pgtable.h
index 268ddde33617..8e00cf9dc39d 100644
--- a/arch/alpha/include/asm/pgtable.h
+++ b/arch/alpha/include/asm/pgtable.h
@@ -127,6 +127,17 @@ struct vm_area_struct;
 #define pgprot_noncached(prot)	(prot)
 
 /*
+ * All caching attribute macros are identity on Alpha, so the generic
+ * pgprot_modify() degenerates to tautological self-comparisons.
+ * Override it to just return newprot directly.
+ */
+#define pgprot_modify pgprot_modify
+static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
+{
+	return newprot;
+}
+
+/*
  * On certain platforms whose physical address space can overlap KSEG,
  * namely EV6 and above, we must re-twiddle the physaddr to restore the
  * correct high-order bits.
diff --git a/arch/alpha/include/asm/seccomp.h b/arch/alpha/include/asm/seccomp.h
new file mode 100644
index 000000000000..311934d20340
--- /dev/null
+++ b/arch/alpha/include/asm/seccomp.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ALPHA_SECCOMP_H
+#define _ASM_ALPHA_SECCOMP_H
+
+#include <asm/unistd.h>
+#include <asm-generic/seccomp.h>
+#include <uapi/linux/audit.h>
+
+#define SECCOMP_ARCH_NATIVE            AUDIT_ARCH_ALPHA
+#define SECCOMP_ARCH_NATIVE_NR         NR_syscalls
+#define SECCOMP_ARCH_NATIVE_NAME       "alpha"
+
+#endif /* _ASM_ALPHA_SECCOMP_H */
diff --git a/arch/alpha/include/asm/syscall.h b/arch/alpha/include/asm/syscall.h
index f21babaeed85..584b1ab2e325 100644
--- a/arch/alpha/include/asm/syscall.h
+++ b/arch/alpha/include/asm/syscall.h
@@ -3,6 +3,10 @@
 #define _ASM_ALPHA_SYSCALL_H
 
 #include <uapi/linux/audit.h>
+#include <linux/audit.h>
+#include <linux/sched.h>
+#include <linux/types.h>
+#include <asm/ptrace.h>
 
 static inline int syscall_get_arch(struct task_struct *task)
 {
@@ -12,7 +16,91 @@ static inline int syscall_get_arch(struct task_struct *task)
 static inline long syscall_get_return_value(struct task_struct *task,
 					    struct pt_regs *regs)
 {
-	return regs->r0;
+	return regs->r19 ? -(long)regs->r0 : (long)regs->r0;
+}
+
+/*
+ * Alpha syscall ABI / kernel conventions:
+ *  - PAL provides syscall number in r0 on entry.
+ *  - The kernel tracks the active syscall number in regs->r1 (mutable) and
+ *    preserves the original syscall number in regs->r2 for rollback/restart.
+ *  - Return value is in regs->r0, with regs->r19 ("a3") as the error flag
+ *    (0=success, 1=error; on error regs->r0 holds positive errno).
+ */
+
+static inline long syscall_get_nr(struct task_struct *task,
+				struct pt_regs *regs)
+{
+	return (long)regs->r1;
+}
+
+static inline void syscall_set_nr(struct task_struct *task,
+				struct pt_regs *regs,
+				long nr)
+{
+	regs->r1 = (unsigned long)nr;
+}
+
+/*
+ * Syscall arguments:
+ *   regs->r16..regs->r21 carry up to 6 syscall arguments on entry.
+ *   Note: regs->r19 is also used as "a3" (error flag) on syscall return.
+ */
+
+static inline void syscall_get_arguments(struct task_struct *task,
+					struct pt_regs *regs,
+					unsigned long *args)
+{
+	args[0] = regs->r16;
+	args[1] = regs->r17;
+	args[2] = regs->r18;
+	args[3] = regs->r19;
+	args[4] = regs->r20;
+	args[5] = regs->r21;
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+					struct pt_regs *regs,
+					const unsigned long *args)
+{
+	regs->r16 = args[0];
+	regs->r17 = args[1];
+	regs->r18 = args[2];
+	regs->r19 = args[3];
+	regs->r20 = args[4];
+	regs->r21 = args[5];
+}
+/*
+ * Set return value for a syscall.
+ * Alpha uses r0 for return value and r19 ("a3") as the error indicator:
+ *   a3 = 0 => success
+ *   a3 = 1 => error, and userspace interprets r0 as errno (positive).
+ *
+ * The kernel reports errors to userspace by setting a3=1 and placing a
+ * positive errno value in r0. Some syscall paths do this in entry.S,
+ * while others (e.g. seccomp/ptrace helpers) use syscall_set_return_value().
+ */
+
+static inline void syscall_set_return_value(struct task_struct *task,
+					struct pt_regs *regs,
+					int error, long val)
+{
+
+	if (error) {
+		/* error is negative errno in this tree */
+		regs->r0  = (unsigned long)(-error);  /* positive errno */
+		regs->r19 = 1;                        /* a3 = error */
+	} else {
+		regs->r0  = (unsigned long)val;
+		regs->r19 = 0;                        /* a3 = success */
+	}
+}
+
+/* Restore the original syscall nr after seccomp/ptrace modified regs->r1. */
+static inline void syscall_rollback(struct task_struct *task,
+					struct pt_regs *regs)
+{
+	regs->r1 = regs->r2;
 }
 
 #endif	/* _ASM_ALPHA_SYSCALL_H */
diff --git a/arch/alpha/include/asm/thread_info.h b/arch/alpha/include/asm/thread_info.h
index 98ccbca64984..94ef9cfa30f5 100644
--- a/arch/alpha/include/asm/thread_info.h
+++ b/arch/alpha/include/asm/thread_info.h
@@ -56,7 +56,8 @@ register unsigned long *current_stack_pointer __asm__ ("$30");
  * - pending work-to-be-done flags come first and must be assigned to be
  *   within bits 0 to 7 to fit in and immediate operand.
  *
- * TIF_SYSCALL_TRACE is known to be 0 via blbs.
+ * (Historically TIF_SYSCALL_TRACE was known to be 0 via blbs, but we may
+ *  also test multiple bits via masks now.)
  */
 #define TIF_SYSCALL_TRACE	0	/* syscall trace active */
 #define TIF_NOTIFY_RESUME	1	/* callback before returning to user */
@@ -64,6 +65,7 @@ register unsigned long *current_stack_pointer __asm__ ("$30");
 #define TIF_NEED_RESCHED	3	/* rescheduling necessary */
 #define TIF_SYSCALL_AUDIT	4	/* syscall audit active */
 #define TIF_NOTIFY_SIGNAL	5	/* signal notifications exist */
+#define TIF_SECCOMP		6	/* seccomp syscall filtering active */
 #define TIF_DIE_IF_KERNEL	9	/* dik recursion lock */
 #define TIF_MEMDIE		13	/* is terminating due to OOM killer */
 #define TIF_POLLING_NRFLAG	14	/* idle is polling for TIF_NEED_RESCHED */
@@ -74,8 +76,20 @@ register unsigned long *current_stack_pointer __asm__ ("$30");
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
 #define _TIF_SYSCALL_AUDIT	(1<<TIF_SYSCALL_AUDIT)
 #define _TIF_NOTIFY_SIGNAL	(1<<TIF_NOTIFY_SIGNAL)
+#define _TIF_SECCOMP		(1<<TIF_SECCOMP)
 #define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)
 
+/*
+ * Work to do on syscall entry (in entry.S).
+ * If you want this to exactly mirror what entry.S checks, keep it aligned
+ * with the mask used before branching to syscall_trace_enter().
+ */
+#ifdef CONFIG_AUDITSYSCALL
+# define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP)
+#else
+# define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SECCOMP)
+#endif
+
 /* Work to do on interrupt/exception return.  */
 #define _TIF_WORK_MASK		(_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
 				 _TIF_NOTIFY_RESUME | _TIF_NOTIFY_SIGNAL)