linux-kernel - [PATCH 5.16 147/285] parisc: Fix patch code locking and flushing

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Date:   Tue, 12 Apr 2022 08:30:04 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, John David Anglin <dave.anglin@...l.net>,
        Helge Deller <deller@....de>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.16 147/285] parisc: Fix patch code locking and flushing

From: John David Anglin <dave.anglin@...l.net>

[ Upstream commit a9fe7fa7d874a536e0540469f314772c054a0323 ]

This change fixes the following:

1) The flags variable is not initialized. Always use raw_spin_lock_irqsave
and raw_spin_unlock_irqrestore to serialize patching.

2) flush_kernel_vmap_range is primarily intended for DMA flushes. Since
__patch_text_multiple is often called with interrupts disabled, it is
better to directly call flush_kernel_dcache_range_asm and
flush_kernel_icache_range_asm. This avoids an extra call.

3) The final call to flush_icache_range is unnecessary.

Signed-off-by: John David Anglin <dave.anglin@...l.net>
Signed-off-by: Helge Deller <deller@....de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/parisc/kernel/patch.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/arch/parisc/kernel/patch.c b/arch/parisc/kernel/patch.c
index 80a0ab372802..e59574f65e64 100644
--- a/arch/parisc/kernel/patch.c
+++ b/arch/parisc/kernel/patch.c
@@ -40,10 +40,7 @@ static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags,
 
 	*need_unmap = 1;
 	set_fixmap(fixmap, page_to_phys(page));
-	if (flags)
-		raw_spin_lock_irqsave(&patch_lock, *flags);
-	else
-		__acquire(&patch_lock);
+	raw_spin_lock_irqsave(&patch_lock, *flags);
 
 	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
 }
@@ -52,10 +49,7 @@ static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
 {
 	clear_fixmap(fixmap);
 
-	if (flags)
-		raw_spin_unlock_irqrestore(&patch_lock, *flags);
-	else
-		__release(&patch_lock);
+	raw_spin_unlock_irqrestore(&patch_lock, *flags);
 }
 
 void __kprobes __patch_text_multiple(void *addr, u32 *insn, unsigned int len)
@@ -67,8 +61,9 @@ void __kprobes __patch_text_multiple(void *addr, u32 *insn, unsigned int len)
 	int mapped;
 
 	/* Make sure we don't have any aliases in cache */
-	flush_kernel_vmap_range(addr, len);
-	flush_icache_range(start, end);
+	flush_kernel_dcache_range_asm(start, end);
+	flush_kernel_icache_range_asm(start, end);
+	flush_tlb_kernel_range(start, end);
 
 	p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &flags, &mapped);
 
@@ -81,8 +76,10 @@ void __kprobes __patch_text_multiple(void *addr, u32 *insn, unsigned int len)
 			 * We're crossing a page boundary, so
 			 * need to remap
 			 */
-			flush_kernel_vmap_range((void *)fixmap,
-						(p-fixmap) * sizeof(*p));
+			flush_kernel_dcache_range_asm((unsigned long)fixmap,
+						      (unsigned long)p);
+			flush_tlb_kernel_range((unsigned long)fixmap,
+					       (unsigned long)p);
 			if (mapped)
 				patch_unmap(FIX_TEXT_POKE0, &flags);
 			p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &flags,
@@ -90,10 +87,10 @@ void __kprobes __patch_text_multiple(void *addr, u32 *insn, unsigned int len)
 		}
 	}
 
-	flush_kernel_vmap_range((void *)fixmap, (p-fixmap) * sizeof(*p));
+	flush_kernel_dcache_range_asm((unsigned long)fixmap, (unsigned long)p);
+	flush_tlb_kernel_range((unsigned long)fixmap, (unsigned long)p);
 	if (mapped)
 		patch_unmap(FIX_TEXT_POKE0, &flags);
-	flush_icache_range(start, end);
 }
 
 void __kprobes __patch_text(void *addr, u32 insn)
-- 
2.35.1