Patch "powerpc/64s: fix hash page fault interrupt handler" has been added to the 5.13-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    powerpc/64s: fix hash page fault interrupt handler

to the 5.13-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-64s-fix-hash-page-fault-interrupt-handler.patch
and it can be found in the queue-5.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 86c2e00d53230df19f68e2f39414a88f81c7b435
Author: Nicholas Piggin <npiggin@xxxxxxxxx>
Date:   Wed Jun 30 17:46:13 2021 +1000

    powerpc/64s: fix hash page fault interrupt handler
    
    [ Upstream commit 5567b1ee29b7a83e8c01d99d34b5bbd306ce0bcf ]
    
    The early bad fault or key fault test in do_hash_fault() ends up calling
    into ___do_page_fault without having gone through an interrupt handler
    wrapper (except the initial _RAW one). This can end up calling local irq
    functions while the interrupt has not been reconciled, which will likely
    cause crashes and it trips up on a later patch that adds more assertions.
    
    pkey_exec_prot from selftests causes this path to be executed.
    
    There is no real reason to run the in_nmi() test should be performed
    before the key fault check. In fact if a perf interrupt in the hash
    fault code did a stack walk that was made to take a key fault somehow
    then running ___do_page_fault could possibly cause another hash fault
    causing problems. Move the in_nmi() test first, and then do everything
    else inside the regular interrupt handler function.
    
    Fixes: 3a96570ffceb ("powerpc: convert interrupt handlers to use wrappers")
    Reported-by: Sachin Sant <sachinp@xxxxxxxxxxxxxxxxxx>
    Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
    Tested-by: Sachin Sant <sachinp@xxxxxxxxxxxxxxxxxx>
    Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20210630074621.2109197-2-npiggin@xxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index 96d9aa164007..ac5720371c0d 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -1522,8 +1522,8 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap,
 }
 EXPORT_SYMBOL_GPL(hash_page);
 
-DECLARE_INTERRUPT_HANDLER_RET(__do_hash_fault);
-DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault)
+DECLARE_INTERRUPT_HANDLER(__do_hash_fault);
+DEFINE_INTERRUPT_HANDLER(__do_hash_fault)
 {
 	unsigned long ea = regs->dar;
 	unsigned long dsisr = regs->dsisr;
@@ -1533,6 +1533,11 @@ DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault)
 	unsigned int region_id;
 	long err;
 
+	if (unlikely(dsisr & (DSISR_BAD_FAULT_64S | DSISR_KEYFAULT))) {
+		hash__do_page_fault(regs);
+		return;
+	}
+
 	region_id = get_region_id(ea);
 	if ((region_id == VMALLOC_REGION_ID) || (region_id == IO_REGION_ID))
 		mm = &init_mm;
@@ -1571,9 +1576,10 @@ DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault)
 			bad_page_fault(regs, SIGBUS);
 		}
 		err = 0;
-	}
 
-	return err;
+	} else if (err) {
+		hash__do_page_fault(regs);
+	}
 }
 
 /*
@@ -1582,13 +1588,6 @@ DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault)
  */
 DEFINE_INTERRUPT_HANDLER_RAW(do_hash_fault)
 {
-	unsigned long dsisr = regs->dsisr;
-
-	if (unlikely(dsisr & (DSISR_BAD_FAULT_64S | DSISR_KEYFAULT))) {
-		hash__do_page_fault(regs);
-		return 0;
-	}
-
 	/*
 	 * If we are in an "NMI" (e.g., an interrupt when soft-disabled), then
 	 * don't call hash_page, just fail the fault. This is required to
@@ -1607,8 +1606,7 @@ DEFINE_INTERRUPT_HANDLER_RAW(do_hash_fault)
 		return 0;
 	}
 
-	if (__do_hash_fault(regs))
-		hash__do_page_fault(regs);
+	__do_hash_fault(regs);
 
 	return 0;
 }