From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>,
Nicolai Stange <nstange@suse.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
the arch/x86 maintainers <x86@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
Petr Mladek <pmladek@suse.com>,
Joe Lawrence <joe.lawrence@redhat.com>,
Shuah Khan <shuah@kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Mimi Zohar <zohar@linux.ibm.com>, Juergen Gross <jgross@suse.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Nayna Jain <nayna@linux.ibm.com>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Joerg Roedel <jroedel@suse.de>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>,
stable@vger.kernel.org, Masami Hiramatsu <mhiramat@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: [for-next][PATCH 02/13] x86_64: Allow breakpoints to emulate call instructions
Date: Wed, 08 May 2019 16:24:29 -0400 [thread overview]
Message-ID: <20190508202452.072839447@goodmis.org> (raw)
In-Reply-To: 20190508202427.252736423@goodmis.org
From: Peter Zijlstra <peterz@infradead.org>
In order to allow breakpoints to emulate call instructions, they need to push
the return address onto the stack. The x86_64 int3 handler adds a small gap
to allow the stack to grow some. Use this gap to add the return address to
be able to emulate a call instruction at the breakpoint location.
These helper functions are added:
int3_emulate_jmp(): changes the location of the regs->ip to return there.
(The next two are only for x86_64)
int3_emulate_push(): to push the address onto the gap in the stack
int3_emulate_call(): push the return address and change regs->ip
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Nicolai Stange <nstange@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: the arch/x86 maintainers <x86@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: "open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@vger.kernel.org>
Cc: stable@vger.kernel.org
Fixes: b700e7f03df5 ("livepatch: kernel: add support for live patching")
Tested-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[ Modified to only work for x86_64 and added comment to int3_emulate_push() ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
arch/x86/include/asm/text-patching.h | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index e85ff65c43c3..05861cc08787 100644
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -39,4 +39,32 @@ extern int poke_int3_handler(struct pt_regs *regs);
extern void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler);
extern int after_bootmem;
+static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip)
+{
+ regs->ip = ip;
+}
+
+#define INT3_INSN_SIZE 1
+#define CALL_INSN_SIZE 5
+
+#ifdef CONFIG_X86_64
+static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val)
+{
+ /*
+ * The int3 handler in entry_64.S adds a gap between the
+ * stack where the break point happened, and the saving of
+ * pt_regs. We can extend the original stack because of
+ * this gap. See the idtentry macro's create_gap option.
+ */
+ regs->sp -= sizeof(unsigned long);
+ *(unsigned long *)regs->sp = val;
+}
+
+static inline void int3_emulate_call(struct pt_regs *regs, unsigned long func)
+{
+ int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE);
+ int3_emulate_jmp(regs, func);
+}
+#endif
+
#endif /* _ASM_X86_TEXT_PATCHING_H */
--
2.20.1
next prev parent reply other threads:[~2019-05-08 20:25 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-08 20:24 [for-next][PATCH 00/13] tracing: Some more last minute changes and fixes Steven Rostedt
2019-05-08 20:24 ` [for-next][PATCH 01/13] x86_64: Add gap to int3 to allow for call emulation Steven Rostedt
2019-05-08 20:24 ` Steven Rostedt [this message]
2019-05-08 20:24 ` [for-next][PATCH 03/13] ftrace/x86_64: Emulate call function while updating in breakpoint handler Steven Rostedt
2019-05-08 20:24 ` [for-next][PATCH 04/13] tracing: uprobes: Re-enable $comm support for uprobe events Steven Rostedt
2019-05-08 20:24 ` [for-next][PATCH 05/13] tracing: probeevent: Do not accumulate on ret variable Steven Rostedt
2019-05-08 20:24 ` [for-next][PATCH 06/13] tracing: probeevent: Fix to make the type of $comm string Steven Rostedt
2019-05-08 20:24 ` [for-next][PATCH 07/13] ring-buffer: Fix mispelling of Calculate Steven Rostedt
2019-05-08 20:24 ` [for-next][PATCH 08/13] tracing: Eliminate const char[] auto variables Steven Rostedt
2019-05-08 20:24 ` [for-next][PATCH 09/13] tracing: Fix white space issues in parse_pred() function Steven Rostedt
2019-05-08 20:24 ` [for-next][PATCH 10/13] tracing: Allow RCU to run between postponed startup tests Steven Rostedt
2019-05-08 20:24 ` [for-next][PATCH 11/13] tracing: Fix partial reading of trace events id file Steven Rostedt
2019-05-08 20:24 ` [for-next][PATCH 12/13] tracing: Replace kzalloc with kcalloc Steven Rostedt
2019-05-08 20:24 ` [for-next][PATCH 13/13] tracing: Fix documentation about disabling options using trace_options Steven Rostedt
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