--- /dev/null
+From 015d98149b326e0f1f02e44413112ca8b4330543 Mon Sep 17 00:00:00 2001
+From: Nathan Chancellor <nathan@kernel.org>
+Date: Fri, 28 May 2021 11:27:52 -0700
+Subject: powerpc/barrier: Avoid collision with clang's __lwsync macro
+
+From: Nathan Chancellor <nathan@kernel.org>
+
+commit 015d98149b326e0f1f02e44413112ca8b4330543 upstream.
+
+A change in clang 13 results in the __lwsync macro being defined as
+__builtin_ppc_lwsync, which emits 'lwsync' or 'msync' depending on what
+the target supports. This breaks the build because of -Werror in
+arch/powerpc, along with thousands of warnings:
+
+ In file included from arch/powerpc/kernel/pmc.c:12:
+ In file included from include/linux/bug.h:5:
+ In file included from arch/powerpc/include/asm/bug.h:109:
+ In file included from include/asm-generic/bug.h:20:
+ In file included from include/linux/kernel.h:12:
+ In file included from include/linux/bitops.h:32:
+ In file included from arch/powerpc/include/asm/bitops.h:62:
+ arch/powerpc/include/asm/barrier.h:49:9: error: '__lwsync' macro redefined [-Werror,-Wmacro-redefined]
+ #define __lwsync() __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory")
+ ^
+ <built-in>:308:9: note: previous definition is here
+ #define __lwsync __builtin_ppc_lwsync
+ ^
+ 1 error generated.
+
+Undefine this macro so that the runtime patching introduced by
+commit 2d1b2027626d ("powerpc: Fixup lwsync at runtime") continues to
+work properly with clang and the build no longer breaks.
+
+Cc: stable@vger.kernel.org
+Signed-off-by: Nathan Chancellor <nathan@kernel.org>
+Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
+Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
+Link: https://github.com/ClangBuiltLinux/linux/issues/1386
+Link: https://github.com/llvm/llvm-project/commit/62b5df7fe2b3fda1772befeda15598fbef96a614
+Link: https://lore.kernel.org/r/20210528182752.1852002-1-nathan@kernel.org
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/powerpc/include/asm/barrier.h | 2 ++
+ 1 file changed, 2 insertions(+)
+
+--- a/arch/powerpc/include/asm/barrier.h
++++ b/arch/powerpc/include/asm/barrier.h
+@@ -44,6 +44,8 @@
+ # define SMPWMB eieio
+ #endif
+
++/* clang defines this macro for a builtin, which will not work with runtime patching */
++#undef __lwsync
+ #define __lwsync() __asm__ __volatile__ (stringify_in_c(LWSYNC) : : :"memory")
+ #define dma_rmb() __lwsync()
+ #define dma_wmb() __asm__ __volatile__ (stringify_in_c(SMPWMB) : : :"memory")
--- /dev/null
+From cd5d5e602f502895e47e18cd46804d6d7014e65c Mon Sep 17 00:00:00 2001
+From: Christophe Leroy <christophe.leroy@csgroup.eu>
+Date: Thu, 1 Jul 2021 11:17:08 +0000
+Subject: powerpc/mm: Fix lockup on kernel exec fault
+
+From: Christophe Leroy <christophe.leroy@csgroup.eu>
+
+commit cd5d5e602f502895e47e18cd46804d6d7014e65c upstream.
+
+The powerpc kernel is not prepared to handle exec faults from kernel.
+Especially, the function is_exec_fault() will return 'false' when an
+exec fault is taken by kernel, because the check is based on reading
+current->thread.regs->trap which contains the trap from user.
+
+For instance, when provoking a LKDTM EXEC_USERSPACE test,
+current->thread.regs->trap is set to SYSCALL trap (0xc00), and
+the fault taken by the kernel is not seen as an exec fault by
+set_access_flags_filter().
+
+Commit d7df2443cd5f ("powerpc/mm: Fix spurious segfaults on radix
+with autonuma") made it clear and handled it properly. But later on
+commit d3ca587404b3 ("powerpc/mm: Fix reporting of kernel execute
+faults") removed that handling, introducing test based on error_code.
+And here is the problem, because on the 603 all upper bits of SRR1
+get cleared when the TLB instruction miss handler bails out to ISI.
+
+Until commit cbd7e6ca0210 ("powerpc/fault: Avoid heavy
+search_exception_tables() verification"), an exec fault from kernel
+at a userspace address was indirectly caught by the lack of entry for
+that address in the exception tables. But after that commit the
+kernel mainly relies on KUAP or on core mm handling to catch wrong
+user accesses. Here the access is not wrong, so mm handles it.
+It is a minor fault because PAGE_EXEC is not set,
+set_access_flags_filter() should set PAGE_EXEC and voila.
+But as is_exec_fault() returns false as explained in the beginning,
+set_access_flags_filter() bails out without setting PAGE_EXEC flag,
+which leads to a forever minor exec fault.
+
+As the kernel is not prepared to handle such exec faults, the thing to
+do is to fire in bad_kernel_fault() for any exec fault taken by the
+kernel, as it was prior to commit d3ca587404b3.
+
+Fixes: d3ca587404b3 ("powerpc/mm: Fix reporting of kernel execute faults")
+Cc: stable@vger.kernel.org # v4.14+
+Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
+Acked-by: Nicholas Piggin <npiggin@gmail.com>
+Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
+Link: https://lore.kernel.org/r/024bb05105050f704743a0083fe3548702be5706.1625138205.git.christophe.leroy@csgroup.eu
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/powerpc/mm/fault.c | 4 +---
+ 1 file changed, 1 insertion(+), 3 deletions(-)
+
+--- a/arch/powerpc/mm/fault.c
++++ b/arch/powerpc/mm/fault.c
+@@ -204,9 +204,7 @@ static bool bad_kernel_fault(struct pt_r
+ {
+ int is_exec = TRAP(regs) == 0x400;
+
+- /* NX faults set DSISR_PROTFAULT on the 8xx, DSISR_NOEXEC_OR_G on others */
+- if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT |
+- DSISR_PROTFAULT))) {
++ if (is_exec) {
+ pr_crit_ratelimited("kernel tried to execute %s page (%lx) - exploit attempt? (uid: %d)\n",
+ address >= TASK_SIZE ? "exec-protected" : "user",
+ address,
projects / thirdparty / kernel / stable-queue.git / commitdiff
