From: Nick Alcock <nick.alcock@oracle.com>
Date: Fri, 12 Dec 2014 19:28:55 +0000 (+0000)
Subject: dtrace: stub syscall fixes for 3.18.
X-Git-Tag: v4.1.12-92~313^2~25
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=7a4e1315ebecd02cb0b051d5b663bf8596ac073e;p=users%2Fjedix%2Flinux-maple.git

dtrace: stub syscall fixes for 3.18.

Fallout from Al Viro's pt_regs argument excision in 3.9.

Orabug: 20456825

Signed-off-by: Nick Alcock <nick.alcock@oracle.com>
Acked-by: Kris Van Hees <kris.van.hees@oracle.com>
---

diff --git a/arch/x86/kernel/dtrace_syscall.c b/arch/x86/kernel/dtrace_syscall.c
index 85c9c1043785..a31fe68c9c4e 100644
--- a/arch/x86/kernel/dtrace_syscall.c
+++ b/arch/x86/kernel/dtrace_syscall.c
@@ -218,16 +218,22 @@ long dtrace_sys_execve(const char __user *name,
 	return rc;
 }
 
-long dtrace_sys_iopl(unsigned int level, struct pt_regs *regs)
+long dtrace_sys_iopl(unsigned int level)
 {
 	long			rc = 0;
 	dtrace_id_t		id;
 	dtrace_syscalls_t	*sc;
+	struct pt_regs		*regs = current_pt_regs();
 	unsigned int		old = (regs->flags >> 12) & 3;
 	struct thread_struct	*t = &current->thread;
 
 	sc = &systrace_info.sysent[__NR_iopl];
 
+	/*
+	 * regs is an argument de facto since it is plucked straight out of the
+	 * stack frame by current_pt_regs().
+	 */
+
 	if ((id = sc->stsy_entry) != DTRACE_IDNONE)
 		(*systrace_probe)(id, (uintptr_t)level, (uintptr_t)regs,
 				  0, 0, 0, 0);
@@ -261,14 +267,20 @@ out:
 	return rc;
 }
 
-long dtrace_sys_rt_sigreturn(struct pt_regs *regs)
+long dtrace_sys_rt_sigreturn(void)
 {
 	long			rc = 0;
 	dtrace_id_t		id;
 	dtrace_syscalls_t	*sc;
+	struct pt_regs		*regs = current_pt_regs();
 
 	sc = &systrace_info.sysent[__NR_rt_sigreturn];
 
+	/*
+	 * regs is an argument de facto since it is plucked straight out of the
+	 * stack frame by current_pt_regs().
+	 */
+
 	if ((id = sc->stsy_entry) != DTRACE_IDNONE)
 		(*systrace_probe)(id, (uintptr_t)regs, 0, 0, 0, 0, 0);
 
@@ -276,7 +288,7 @@ long dtrace_sys_rt_sigreturn(struct pt_regs *regs)
 	 * FIXME: Add stop functionality for DTrace.
 	 */
 
-	rc = sys_rt_sigreturn(regs);
+	rc = sys_rt_sigreturn();
 
 	if ((id = sc->stsy_return) != DTRACE_IDNONE)
 		(*systrace_probe)(id, (uintptr_t)rc, (uintptr_t)rc,
diff --git a/arch/x86/kernel/dtrace_syscall_stubs.S b/arch/x86/kernel/dtrace_syscall_stubs.S
index b10a6a97847a..285ebb567188 100644
--- a/arch/x86/kernel/dtrace_syscall_stubs.S
+++ b/arch/x86/kernel/dtrace_syscall_stubs.S
@@ -141,23 +141,6 @@
 	CFI_REL_OFFSET r15, R15+\offset
 	.endm
 
-/*
- * Certain special system calls that need to save a complete full stack frame.
- */
-	.macro PTREGSCALL label,func,arg
-ENTRY(\label)
-	PARTIAL_FRAME 1 8		/* offset 8: return address */
-	subq $REST_SKIP, %rsp
-	CFI_ADJUST_CFA_OFFSET REST_SKIP
-	call save_rest
-	DEFAULT_FRAME 0 8		/* offset 8: return address */
-	leaq 8(%rsp), \arg	/* pt_regs pointer */
-	call \func
-	jmp ptregscall_common
-	CFI_ENDPROC
-END(\label)
-	.endm
-
 	.macro FORK_LIKE func
 ENTRY(dtrace_stub_\func)
 	CFI_STARTPROC
@@ -174,10 +157,22 @@ ENTRY(dtrace_stub_\func)
 END(dtrace_stub_\func)
 	.endm
 
+	.macro FIXED_FRAME label,func
+ENTRY(\label)
+	CFI_STARTPROC
+	PARTIAL_FRAME 0 8		/* offset 8: return address */
+	FIXUP_TOP_OF_STACK %r11, 8-ARGOFFSET
+	call \func
+	RESTORE_TOP_OF_STACK %r11, 8-ARGOFFSET
+	ret
+	CFI_ENDPROC
+END(\label)
+	.endm
+
         FORK_LIKE  clone
         FORK_LIKE  fork
         FORK_LIKE  vfork
-	PTREGSCALL dtrace_stub_iopl, dtrace_sys_iopl, %rsi
+	FIXED_FRAME dtrace_stub_iopl, dtrace_sys_iopl
 
 ENTRY(dtrace_stub_execve)
 	CFI_STARTPROC
@@ -186,7 +181,6 @@ ENTRY(dtrace_stub_execve)
 	SAVE_REST
 	FIXUP_TOP_OF_STACK %r11
 	call dtrace_sys_execve
-	RESTORE_TOP_OF_STACK %r11
 	movq %rax,RAX(%rsp)
 	RESTORE_REST
 	jmp int_ret_from_sys_call
@@ -202,7 +196,6 @@ ENTRY(dtrace_stub_rt_sigreturn)
 	addq $8, %rsp
 	PARTIAL_FRAME 0
 	SAVE_REST
-	movq %rsp,%rdi
 	FIXUP_TOP_OF_STACK %r11
 	call dtrace_sys_rt_sigreturn
 	movq %rax,RAX(%rsp) # fixme, this could be done at the higher layer