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xtensa: provide custom CALLER_ADDR* implementations

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Definition of CALLER_ADDR* through __builtin_return_address makes
compiler insert calls to __xtensa_libgcc_window_spill, which in turn
makes fast_syscall_spill_registers syscall that clobbers registers when
called from the kernel mode, leading to invalid opcode exceptions on
return to userspace.

Provide definition for CALLER_ADDR0 as MAKE_PC_FROM_RA(a0, a1) and in
case CONFIG_FRAME_POINTER is enabled extract CALLER_ADDR{1-3} from
stack.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
This commit is contained in:
Max Filippov 2013-04-08 01:29:19 +04:00 committed by Chris Zankel
parent 3e4196a5cc
commit 3ae908c99e
2 changed files with 66 additions and 1 deletions
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34
arch/xtensa/include/asm/ftrace.h
View File

@ -1 +1,33 @@
/* empty */
/*
* arch/xtensa/include/asm/ftrace.h
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2013 Tensilica Inc.
*/
#ifndef _XTENSA_FTRACE_H
#define _XTENSA_FTRACE_H
#include <asm/processor.h>
#define HAVE_ARCH_CALLER_ADDR
#define CALLER_ADDR0 ({ unsigned long a0, a1; \
__asm__ __volatile__ ( \
"mov %0, a0\n" \
"mov %1, a1\n" \
: "=r"(a0), "=r"(a1) : : ); \
MAKE_PC_FROM_RA(a0, a1); })
#ifdef CONFIG_FRAME_POINTER
extern unsigned long return_address(unsigned level);
#define CALLER_ADDR1 return_address(1)
#define CALLER_ADDR2 return_address(2)
#define CALLER_ADDR3 return_address(3)
#else
#define CALLER_ADDR1 (0)
#define CALLER_ADDR2 (0)
#define CALLER_ADDR3 (0)
#endif
#endif /* _XTENSA_FTRACE_H */

33
arch/xtensa/kernel/stacktrace.c
View File

@ -85,3 +85,36 @@ void save_stack_trace(struct stack_trace *trace)
EXPORT_SYMBOL_GPL(save_stack_trace);
#endif
#ifdef CONFIG_FRAME_POINTER
struct return_addr_data {
unsigned long addr;
unsigned skip;
};
static int return_address_cb(struct stackframe *frame, void *data)
{
struct return_addr_data *r = data;
if (r->skip) {
--r->skip;
return 0;
}
if (!kernel_text_address(frame->pc))
return 0;
r->addr = frame->pc;
return 1;
}
unsigned long return_address(unsigned level)
{
struct return_addr_data r = {
.skip = level + 1,
};
walk_stackframe(stack_pointer(NULL), return_address_cb, &r);
return r.addr;
}
EXPORT_SYMBOL(return_address);
#endif