From: Paul Mackerras <paulus@samba.org>
To: akpm@osdl.org, torvalds@osdl.org
Cc: anton@samba.org, linux-kernel@vger.kernel.org,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Subject: [PATCH] ppc64: kprobes: handle trap variants while processing probes
Date: Mon, 7 Mar 2005 20:52:04 +1100 [thread overview]
Message-ID: <16940.9284.79566.526069@cargo.ozlabs.ibm.com> (raw)
This patch is from Ananth N Mavinakayanahalli <ananth@in.ibm.com>.
While processing a kprobe, we were currently not handling all available
trap variants available on PowerPC. This lead to the breakage of BUG()
handling in ppc64.
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff -Naurp temp/linux-2.6.11-rc3/arch/ppc64/kernel/kprobes.c linux-2.6.11-rc3/arch/ppc64/kernel/kprobes.c
--- temp/linux-2.6.11-rc3/arch/ppc64/kernel/kprobes.c 2005-02-03 07:26:53.000000000 +0530
+++ linux-2.6.11-rc3/arch/ppc64/kernel/kprobes.c 2005-02-10 18:08:25.000000000 +0530
@@ -105,8 +105,16 @@ static inline int kprobe_handler(struct
p = get_kprobe(addr);
if (!p) {
unlock_kprobes();
-#if 0
if (*addr != BREAKPOINT_INSTRUCTION) {
+ /*
+ * PowerPC has multiple variants of the "trap"
+ * instruction. If the current instruction is a
+ * trap variant, it could belong to someone else
+ */
+ kprobe_opcode_t cur_insn = *addr;
+ if (IS_TW(cur_insn) || IS_TD(cur_insn) ||
+ IS_TWI(cur_insn) || IS_TDI(cur_insn))
+ goto no_kprobe;
/*
* The breakpoint instruction was removed right
* after we hit it. Another cpu has removed
@@ -116,7 +124,6 @@ static inline int kprobe_handler(struct
*/
ret = 1;
}
-#endif
/* Not one of ours: let kernel handle it */
goto no_kprobe;
}
diff -Naurp temp/linux-2.6.11-rc3/include/asm-ppc64/kprobes.h linux-2.6.11-rc3/include/asm-ppc64/kprobes.h
--- temp/linux-2.6.11-rc3/include/asm-ppc64/kprobes.h 2005-02-03 07:25:50.000000000 +0530
+++ linux-2.6.11-rc3/include/asm-ppc64/kprobes.h 2005-02-10 18:08:58.000000000 +0530
@@ -35,6 +35,11 @@ typedef unsigned int kprobe_opcode_t;
#define BREAKPOINT_INSTRUCTION 0x7fe00008 /* trap */
#define MAX_INSN_SIZE 1
+#define IS_TW(instr) (((instr) & 0xfc0007fe) == 0x7c000008)
+#define IS_TD(instr) (((instr) & 0xfc0007fe) == 0x7c000088)
+#define IS_TDI(instr) (((instr) & 0xfc000000) == 0x08000000)
+#define IS_TWI(instr) (((instr) & 0xfc000000) == 0x0c000000)
+
#define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)((func_descr_t *)pentry)
/* Architecture specific copy of original instruction */
reply other threads:[~2005-03-07 9:51 UTC|newest]
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