/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * 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.
 */
#include <asm/cache.h>          /* IFETCH_ALIGN_BYTES */
#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

/*
 * __kernel_start_sigtramp_rt64 and __kernel_sigtramp_rt64 together
 * are one function split in two parts. The kernel jumps to the former
 * and the signal handler indirectly (by blr) returns to the latter.
 * __kernel_sigtramp_rt64 needs to point to the return address so
 * glibc can correctly identify the trampoline stack frame.
 */
        .balign 8
        .balign IFETCH_ALIGN_BYTES
V_FUNCTION_BEGIN(__kernel_start_sigtramp_rt64)
.Lsigrt_start:
        bctrl   /* call the handler */
V_FUNCTION_END(__kernel_start_sigtramp_rt64)
V_FUNCTION_BEGIN(__kernel_sigtramp_rt64)
        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

/* Size of CR reg in DWARF unwind info. */
#define CRSIZE  4

/* Offset of CR reg within a full word. */
#ifdef __LITTLE_ENDIAN__
#define CROFF 0
#else
#define CROFF (RSIZE - CRSIZE)
#endif

/* 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 (68, 38*RSIZE + CROFF); /* cr fields */                         \
  rsave (69, 38*RSIZE + CROFF);                                         \
  rsave (70, 38*RSIZE + CROFF);                                         \
  rsave (71, 38*RSIZE + CROFF);                                         \
  rsave (72, 38*RSIZE + CROFF);                                         \
  rsave (73, 38*RSIZE + CROFF);                                         \
  rsave (74, 38*RSIZE + CROFF);                                         \
  rsave (75, 38*RSIZE + CROFF)

/* 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: