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From: Sven Schnelle <svens@stackframe.org>
To: deller@gmx.de
Cc: linux-parisc@vger.kernel.org, Sven Schnelle <svens@stackframe.org>
Subject: [PATCH 2/6] parisc: add spinlock to patch function
Date: Mon, 27 May 2019 21:04:46 +0200	[thread overview]
Message-ID: <20190527190450.14988-3-svens@stackframe.org> (raw)
In-Reply-To: <20190527190450.14988-1-svens@stackframe.org>

If multiple CPUs are patching code we need the spinlock
to protect against parallel fixmap maps/unmap calls.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
 arch/parisc/kernel/patch.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/arch/parisc/kernel/patch.c b/arch/parisc/kernel/patch.c
index eaef5515f5b6..8ed8e7191e8d 100644
--- a/arch/parisc/kernel/patch.c
+++ b/arch/parisc/kernel/patch.c
@@ -23,7 +23,9 @@ struct patch {
 
 static DEFINE_RAW_SPINLOCK(patch_lock);
 
-static void __kprobes *patch_map(void *addr, int fixmap, int *need_unmap)
+static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags,
+				 int *need_unmap)
+{
 	unsigned long uintaddr = (uintptr_t) addr;
 	bool module = !core_kernel_text(uintaddr);
 	struct page *page;
@@ -38,19 +40,29 @@ static void __kprobes *patch_map(void *addr, int fixmap, int *need_unmap)
 
 	*need_unmap = 1;
 	set_fixmap(fixmap, page_to_phys(page));
+	if (flags)
+		raw_spin_lock_irqsave(&patch_lock, *flags);
+	else
+		__acquire(&patch_lock);
 
 	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
 }
 
-static void __kprobes patch_unmap(int fixmap)
+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);
 }
 
 void __kprobes __patch_text_multiple(void *addr, u32 *insn, int len)
 {
 	unsigned long start = (unsigned long)addr;
 	unsigned long end = (unsigned long)addr + len;
+	unsigned long flags;
 	u32 *p, *fixmap;
 	int mapped;
 
@@ -58,7 +70,7 @@ void __kprobes __patch_text_multiple(void *addr, u32 *insn, int len)
 	flush_kernel_vmap_range(addr, len);
 	flush_icache_range(start, end);
 
-	p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &mapped);
+	p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &flags, &mapped);
 
 	while (len > 0) {
 		*p++ = *insn++;
@@ -72,14 +84,15 @@ void __kprobes __patch_text_multiple(void *addr, u32 *insn, int len)
 			flush_kernel_vmap_range((void *)fixmap,
 						(p-fixmap) * sizeof(*p));
 			if (mapped)
-				patch_unmap(FIX_TEXT_POKE0);
-			p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &mapped);
+				patch_unmap(FIX_TEXT_POKE0, &flags);
+			p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &flags,
+						&mapped);
 		}
 	}
 
 	flush_kernel_vmap_range((void *)fixmap, (p-fixmap) * sizeof(*p));
 	if (mapped)
-		patch_unmap(FIX_TEXT_POKE0);
+		patch_unmap(FIX_TEXT_POKE0, &flags);
 	flush_icache_range(start, end);
 }
 
-- 
2.20.1


  parent reply	other threads:[~2019-05-27 19:05 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-27 19:04 [PATCH 0/6] Dynamic FTRACE for PA-RISC Sven Schnelle
2019-05-27 19:04 ` [PATCH 1/6] parisc: add support for patching multiple words Sven Schnelle
2019-05-28  8:19   ` Rolf Eike Beer
2019-05-29 17:49     ` Sven Schnelle
2019-05-29 17:58       ` Rolf Eike Beer
2019-05-29 18:18         ` Sven Schnelle
2019-05-27 19:04 ` Sven Schnelle [this message]
2019-05-27 19:04 ` [PATCH 3/6] parisc: add WARN_ON() to clear_fixmap Sven Schnelle
2019-05-27 19:04 ` [PATCH 4/6] parisc: use pr_debug() in kernel/module.c Sven Schnelle
2019-05-28  8:24   ` Rolf Eike Beer
2019-05-29 17:54     ` Sven Schnelle
2019-05-27 19:04 ` [PATCH 5/6] compiler.h: add CC_USING_PATCHABLE_FUNCTION_ENTRY Sven Schnelle
2019-05-27 19:04 ` [PATCH 6/6] parisc: add dynamic ftrace Sven Schnelle
2019-05-28  8:26   ` Rolf Eike Beer

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