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authorMax Filippov <jcmvbkbc@gmail.com>2019-12-11 01:23:49 +0300
committerMax Filippov <jcmvbkbc@gmail.com>2022-05-02 05:51:21 +0300
commita8f0c31fa87dcf9154c4209960f1dd1ed6a1aad8 (patch)
treed32478a51694a14cbd5c80e6768ea0869647aa88 /arch/xtensa/mm
parent270a8306917e40746a02494abbd40828356b08e1 (diff)
downloadlinux-a8f0c31fa87dcf9154c4209960f1dd1ed6a1aad8.tar.xz
xtensa: noMMU: allow handling protection faults
Many xtensa CPU cores without full MMU still have memory protection features capable of raising exceptions for invalid instruction fetches/data access. Allow handling such exceptions. This improves behavior of processes that pass invalid memory pointers to syscalls in noMMU configs: in case of exception the kernel instead of killing the process is now able to return -EINVAL from a syscall. Introduce CONFIG_PFAULT that controls whether protection fault code is enabled and register handlers for common memory protection exceptions when it is enabled. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Diffstat (limited to 'arch/xtensa/mm')
-rw-r--r--arch/xtensa/mm/Makefile3
-rw-r--r--arch/xtensa/mm/fault.c4
2 files changed, 6 insertions, 1 deletions
diff --git a/arch/xtensa/mm/Makefile b/arch/xtensa/mm/Makefile
index f7fb08ae768f..44153a335951 100644
--- a/arch/xtensa/mm/Makefile
+++ b/arch/xtensa/mm/Makefile
@@ -4,7 +4,8 @@
#
obj-y := init.o misc.o
-obj-$(CONFIG_MMU) += cache.o fault.o ioremap.o mmu.o tlb.o
+obj-$(CONFIG_PFAULT) += fault.o
+obj-$(CONFIG_MMU) += cache.o ioremap.o mmu.o tlb.o
obj-$(CONFIG_HIGHMEM) += highmem.o
obj-$(CONFIG_KASAN) += kasan_init.o
diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
index 01e66da4a6b0..16f0a5ff5799 100644
--- a/arch/xtensa/mm/fault.c
+++ b/arch/xtensa/mm/fault.c
@@ -25,6 +25,7 @@ void bad_page_fault(struct pt_regs*, unsigned long, int);
static void vmalloc_fault(struct pt_regs *regs, unsigned int address)
{
+#ifdef CONFIG_MMU
/* Synchronize this task's top level page-table
* with the 'reference' page table.
*/
@@ -71,6 +72,9 @@ static void vmalloc_fault(struct pt_regs *regs, unsigned int address)
bad_page_fault:
bad_page_fault(regs, address, SIGKILL);
+#else
+ WARN_ONCE(1, "%s in noMMU configuration\n", __func__);
+#endif
}
/*
* This routine handles page faults. It determines the address,