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linux-stable/arch/powerpc/kernel/vdso64/sigtramp.S
Jakub Jelinek da2e9e1ff4 [PATCH] Mark unwind info for signal trampolines in vDSOs 
Mark unwind info for signal trampolines using the new S augmentation flag
introduced in: http://gcc.gnu.org/PR26208.

GCC 4.2 (or patched earlier GCC) will be able to special case unwinding
through frames right above signal trampolines.  As the augmentations start
with z flag and S is at the very end of the augmentation string, older GCCs
will just skip the S flag as unknown (that's why an augmentation flag was
chosen over say a new CFA opcode).

Signed-off-by: Jakub Jelinek <jakub@redhat.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-31 12:18:52 -08:00

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/*
* Signal trampoline for 64 bits processes in a ppc64 kernel for
* use in the vDSO
*
* Copyright (C) 2004 Benjamin Herrenschmuidt (benh@kernel.crashing.org), IBM Corp.
* Copyright (C) 2004 Alan Modra (amodra@au.ibm.com)), IBM Corp.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/config.h>
#include <asm/processor.h>
#include <asm/ppc_asm.h>
#include <asm/unistd.h>
#include <asm/vdso.h>
#include <asm/ptrace.h> /* XXX for __SIGNAL_FRAMESIZE */
.text
/* The nop here is a hack. The dwarf2 unwind routines subtract 1 from
the return address to get an address in the middle of the presumed
call instruction. Since we don't have a call here, we artifically
extend the range covered by the unwind info by padding before the
real start. */
nop
.balign 8
V_FUNCTION_BEGIN(__kernel_sigtramp_rt64)
.Lsigrt_start = . - 4
addi r1, r1, __SIGNAL_FRAMESIZE
li r0,__NR_rt_sigreturn
sc
.Lsigrt_end:
V_FUNCTION_END(__kernel_sigtramp_rt64)
/* The ".balign 8" above and the following zeros mimic the old stack
trampoline layout. The last magic value is the ucontext pointer,
chosen in such a way that older libgcc unwind code returns a zero
for a sigcontext pointer. */
.long 0,0,0
.quad 0,-21*8
/* Register r1 can be found at offset 8 of a pt_regs structure.
A pointer to the pt_regs is stored in memory at the old sp plus PTREGS. */
#define cfa_save \
.byte 0x0f; /* DW_CFA_def_cfa_expression */ \
.uleb128 9f - 1f; /* length */ \
1: \
.byte 0x71; .sleb128 PTREGS; /* DW_OP_breg1 */ \
.byte 0x06; /* DW_OP_deref */ \
.byte 0x23; .uleb128 RSIZE; /* DW_OP_plus_uconst */ \
.byte 0x06; /* DW_OP_deref */ \
9:
/* Register REGNO can be found at offset OFS of a pt_regs structure.
A pointer to the pt_regs is stored in memory at the old sp plus PTREGS. */
#define rsave(regno, ofs) \
.byte 0x10; /* DW_CFA_expression */ \
.uleb128 regno; /* regno */ \
.uleb128 9f - 1f; /* length */ \
1: \
.byte 0x71; .sleb128 PTREGS; /* DW_OP_breg1 */ \
.byte 0x06; /* DW_OP_deref */ \
.ifne ofs; \
.byte 0x23; .uleb128 ofs; /* DW_OP_plus_uconst */ \
.endif; \
9:
/* If msr bit 1<<25 is set, then VMX register REGNO is at offset REGNO*16
of the VMX reg struct. A pointer to the VMX reg struct is at VREGS in
the pt_regs struct. This macro is for REGNO == 0, and contains
'subroutines' that the other macros jump to. */
#define vsave_msr0(regno) \
.byte 0x10; /* DW_CFA_expression */ \
.uleb128 regno + 77; /* regno */ \
.uleb128 9f - 1f; /* length */ \
1: \
.byte 0x30 + regno; /* DW_OP_lit0 */ \
2: \
.byte 0x40; /* DW_OP_lit16 */ \
.byte 0x1e; /* DW_OP_mul */ \
3: \
.byte 0x71; .sleb128 PTREGS; /* DW_OP_breg1 */ \
.byte 0x06; /* DW_OP_deref */ \
.byte 0x12; /* DW_OP_dup */ \
.byte 0x23; /* DW_OP_plus_uconst */ \
.uleb128 33*RSIZE; /* msr offset */ \
.byte 0x06; /* DW_OP_deref */ \
.byte 0x0c; .long 1 << 25; /* DW_OP_const4u */ \
.byte 0x1a; /* DW_OP_and */ \
.byte 0x12; /* DW_OP_dup, ret 0 if bra taken */ \
.byte 0x30; /* DW_OP_lit0 */ \
.byte 0x29; /* DW_OP_eq */ \
.byte 0x28; .short 0x7fff; /* DW_OP_bra to end */ \
.byte 0x13; /* DW_OP_drop, pop the 0 */ \
.byte 0x23; .uleb128 VREGS; /* DW_OP_plus_uconst */ \
.byte 0x06; /* DW_OP_deref */ \
.byte 0x22; /* DW_OP_plus */ \
.byte 0x2f; .short 0x7fff; /* DW_OP_skip to end */ \
9:
/* If msr bit 1<<25 is set, then VMX register REGNO is at offset REGNO*16
of the VMX reg struct. REGNO is 1 thru 31. */
#define vsave_msr1(regno) \
.byte 0x10; /* DW_CFA_expression */ \
.uleb128 regno + 77; /* regno */ \
.uleb128 9f - 1f; /* length */ \
1: \
.byte 0x30 + regno; /* DW_OP_lit n */ \
.byte 0x2f; .short 2b - 9f; /* DW_OP_skip */ \
9:
/* If msr bit 1<<25 is set, then VMX register REGNO is at offset OFS of
the VMX save block. */
#define vsave_msr2(regno, ofs) \
.byte 0x10; /* DW_CFA_expression */ \
.uleb128 regno + 77; /* regno */ \
.uleb128 9f - 1f; /* length */ \
1: \
.byte 0x0a; .short ofs; /* DW_OP_const2u */ \
.byte 0x2f; .short 3b - 9f; /* DW_OP_skip */ \
9:
/* VMX register REGNO is at offset OFS of the VMX save area. */
#define vsave(regno, ofs) \
.byte 0x10; /* DW_CFA_expression */ \
.uleb128 regno + 77; /* regno */ \
.uleb128 9f - 1f; /* length */ \
1: \
.byte 0x71; .sleb128 PTREGS; /* DW_OP_breg1 */ \
.byte 0x06; /* DW_OP_deref */ \
.byte 0x23; .uleb128 VREGS; /* DW_OP_plus_uconst */ \
.byte 0x06; /* DW_OP_deref */ \
.byte 0x23; .uleb128 ofs; /* DW_OP_plus_uconst */ \
9:
/* This is where the pt_regs pointer can be found on the stack. */
#define PTREGS 128+168+56
/* Size of regs. */
#define RSIZE 8
/* This is the offset of the VMX reg pointer. */
#define VREGS 48*RSIZE+33*8
/* Describe where general purpose regs are saved. */
#define EH_FRAME_GEN \
cfa_save; \
rsave ( 0, 0*RSIZE); \
rsave ( 2, 2*RSIZE); \
rsave ( 3, 3*RSIZE); \
rsave ( 4, 4*RSIZE); \
rsave ( 5, 5*RSIZE); \
rsave ( 6, 6*RSIZE); \
rsave ( 7, 7*RSIZE); \
rsave ( 8, 8*RSIZE); \
rsave ( 9, 9*RSIZE); \
rsave (10, 10*RSIZE); \
rsave (11, 11*RSIZE); \
rsave (12, 12*RSIZE); \
rsave (13, 13*RSIZE); \
rsave (14, 14*RSIZE); \
rsave (15, 15*RSIZE); \
rsave (16, 16*RSIZE); \
rsave (17, 17*RSIZE); \
rsave (18, 18*RSIZE); \
rsave (19, 19*RSIZE); \
rsave (20, 20*RSIZE); \
rsave (21, 21*RSIZE); \
rsave (22, 22*RSIZE); \
rsave (23, 23*RSIZE); \
rsave (24, 24*RSIZE); \
rsave (25, 25*RSIZE); \
rsave (26, 26*RSIZE); \
rsave (27, 27*RSIZE); \
rsave (28, 28*RSIZE); \
rsave (29, 29*RSIZE); \
rsave (30, 30*RSIZE); \
rsave (31, 31*RSIZE); \
rsave (67, 32*RSIZE); /* ap, used as temp for nip */ \
rsave (65, 36*RSIZE); /* lr */ \
rsave (70, 38*RSIZE) /* cr */
/* Describe where the FP regs are saved. */
#define EH_FRAME_FP \
rsave (32, 48*RSIZE + 0*8); \
rsave (33, 48*RSIZE + 1*8); \
rsave (34, 48*RSIZE + 2*8); \
rsave (35, 48*RSIZE + 3*8); \
rsave (36, 48*RSIZE + 4*8); \
rsave (37, 48*RSIZE + 5*8); \
rsave (38, 48*RSIZE + 6*8); \
rsave (39, 48*RSIZE + 7*8); \
rsave (40, 48*RSIZE + 8*8); \
rsave (41, 48*RSIZE + 9*8); \
rsave (42, 48*RSIZE + 10*8); \
rsave (43, 48*RSIZE + 11*8); \
rsave (44, 48*RSIZE + 12*8); \
rsave (45, 48*RSIZE + 13*8); \
rsave (46, 48*RSIZE + 14*8); \
rsave (47, 48*RSIZE + 15*8); \
rsave (48, 48*RSIZE + 16*8); \
rsave (49, 48*RSIZE + 17*8); \
rsave (50, 48*RSIZE + 18*8); \
rsave (51, 48*RSIZE + 19*8); \
rsave (52, 48*RSIZE + 20*8); \
rsave (53, 48*RSIZE + 21*8); \
rsave (54, 48*RSIZE + 22*8); \
rsave (55, 48*RSIZE + 23*8); \
rsave (56, 48*RSIZE + 24*8); \
rsave (57, 48*RSIZE + 25*8); \
rsave (58, 48*RSIZE + 26*8); \
rsave (59, 48*RSIZE + 27*8); \
rsave (60, 48*RSIZE + 28*8); \
rsave (61, 48*RSIZE + 29*8); \
rsave (62, 48*RSIZE + 30*8); \
rsave (63, 48*RSIZE + 31*8)
/* Describe where the VMX regs are saved. */
#ifdef CONFIG_ALTIVEC
#define EH_FRAME_VMX \
vsave_msr0 ( 0); \
vsave_msr1 ( 1); \
vsave_msr1 ( 2); \
vsave_msr1 ( 3); \
vsave_msr1 ( 4); \
vsave_msr1 ( 5); \
vsave_msr1 ( 6); \
vsave_msr1 ( 7); \
vsave_msr1 ( 8); \
vsave_msr1 ( 9); \
vsave_msr1 (10); \
vsave_msr1 (11); \
vsave_msr1 (12); \
vsave_msr1 (13); \
vsave_msr1 (14); \
vsave_msr1 (15); \
vsave_msr1 (16); \
vsave_msr1 (17); \
vsave_msr1 (18); \
vsave_msr1 (19); \
vsave_msr1 (20); \
vsave_msr1 (21); \
vsave_msr1 (22); \
vsave_msr1 (23); \
vsave_msr1 (24); \
vsave_msr1 (25); \
vsave_msr1 (26); \
vsave_msr1 (27); \
vsave_msr1 (28); \
vsave_msr1 (29); \
vsave_msr1 (30); \
vsave_msr1 (31); \
vsave_msr2 (33, 32*16+12); \
vsave (32, 33*16)
#else
#define EH_FRAME_VMX
#endif
.section .eh_frame,"a",@progbits
.Lcie:
.long .Lcie_end - .Lcie_start
.Lcie_start:
.long 0 /* CIE ID */
.byte 1 /* Version number */
.string "zRS" /* NUL-terminated augmentation string */
.uleb128 4 /* Code alignment factor */
.sleb128 -8 /* Data alignment factor */
.byte 67 /* Return address register column, ap */
.uleb128 1 /* Augmentation value length */
.byte 0x14 /* DW_EH_PE_pcrel | DW_EH_PE_udata8. */
.byte 0x0c,1,0 /* DW_CFA_def_cfa: r1 ofs 0 */
.balign 8
.Lcie_end:
.long .Lfde0_end - .Lfde0_start
.Lfde0_start:
.long .Lfde0_start - .Lcie /* CIE pointer. */
.quad .Lsigrt_start - . /* PC start, length */
.quad .Lsigrt_end - .Lsigrt_start
.uleb128 0 /* Augmentation */
EH_FRAME_GEN
EH_FRAME_FP
EH_FRAME_VMX
# Do we really need to describe the frame at this point? ie. will
# we ever have some call chain that returns somewhere past the addi?
# I don't think so, since gcc doesn't support async signals.
# .byte 0x41 /* DW_CFA_advance_loc 1*4 */
#undef PTREGS
#define PTREGS 168+56
# EH_FRAME_GEN
# EH_FRAME_FP
# EH_FRAME_VMX
.balign 8
.Lfde0_end:
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