arm64/boot: Disable trapping of PMZR_EL0 writes to EL2grafted

__init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2.
PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in
HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host
traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The
kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU
driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a
write from EL0 reaches the trap and takes the host down without a panic
message.

Accumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already
does for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9
bits.

Fixes: 858c7bfcb35e1 ("arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9")
Cc: stable@vger.kernel.org
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oliver Upton <oupton@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 29 insertions, 0 deletions

diff --git a/include/asm-generic/syscalls.h b/include/asm-generic/syscalls.h
new file mode 100644
index 000000000..fabcefe8a
--- /dev/null
+++ b/include/asm-generic/syscalls.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_GENERIC_SYSCALLS_H
+#define __ASM_GENERIC_SYSCALLS_H
+
+#include <linux/compiler.h>
+#include <linux/linkage.h>
+
+/*
+ * Calling conventions for these system calls can differ, so
+ * it's possible to override them.
+ */
+
+#ifndef sys_mmap2
+asmlinkage long sys_mmap2(unsigned long addr, unsigned long len,
+			unsigned long prot, unsigned long flags,
+			unsigned long fd, unsigned long pgoff);
+#endif
+
+#ifndef sys_mmap
+asmlinkage long sys_mmap(unsigned long addr, unsigned long len,
+			unsigned long prot, unsigned long flags,
+			unsigned long fd, unsigned long off);
+#endif
+
+#ifndef sys_rt_sigreturn
+asmlinkage long sys_rt_sigreturn(struct pt_regs *regs);
+#endif
+
+#endif /* __ASM_GENERIC_SYSCALLS_H */