releases/4.19.31/arcv2-support-manual-regfile-save-on-interrupts.patch

   1 From e3f16c67527e970e029fda10084bbffb744259ef Mon Sep 17 00:00:00 2001
   2 From: Vineet Gupta <vgupta@synopsys.com>
   3 Date: Wed, 6 Jun 2018 10:20:37 -0700
   4 Subject: ARCv2: support manual regfile save on interrupts
   5
   6 [ Upstream commit e494239a007e601448110ac304fe055951f9de3b ]
   7
   8 There's a hardware bug which affects the HSDK platform, triggered by
   9 micro-ops for auto-saving regfile on taken interrupt. The workaround is
  10 to inhibit autosave.
  11
  12 Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
  13 Signed-off-by: Sasha Levin <sashal@kernel.org>
  14 ---
  15  arch/arc/Kconfig                   |  8 +++++
  16  arch/arc/include/asm/entry-arcv2.h | 54 ++++++++++++++++++++++++++++++
  17  arch/arc/kernel/entry-arcv2.S      |  4 ++-
  18  arch/arc/kernel/intc-arcv2.c       |  2 ++
  19  arch/arc/plat-hsdk/Kconfig         |  1 +
  20  5 files changed, 68 insertions(+), 1 deletion(-)
  21
  22 diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
  23 index ac69f307dcfe..74953e76a57d 100644
  24 --- a/arch/arc/Kconfig
  25 +++ b/arch/arc/Kconfig
  26 @@ -420,6 +420,14 @@ config ARC_HAS_ACCL_REGS
  27           (also referred to as r58:r59). These can also be used by gcc as GPR so
  28           kernel needs to save/restore per process
  29
  30 +config ARC_IRQ_NO_AUTOSAVE
  31 +       bool "Disable hardware autosave regfile on interrupts"
  32 +       default n
  33 +       help
  34 +         On HS cores, taken interrupt auto saves the regfile on stack.
  35 +         This is programmable and can be optionally disabled in which case
  36 +         software INTERRUPT_PROLOGUE/EPILGUE do the needed work
  37 +
  38  endif  # ISA_ARCV2
  39
  40  endmenu   # "ARC CPU Configuration"
  41 diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
  42 index 309f4e6721b3..225e7df2d8ed 100644
  43 --- a/arch/arc/include/asm/entry-arcv2.h
  44 +++ b/arch/arc/include/asm/entry-arcv2.h
  45 @@ -17,6 +17,33 @@
  46         ;
  47         ; Now manually save: r12, sp, fp, gp, r25
  48
  49 +#ifdef CONFIG_ARC_IRQ_NO_AUTOSAVE
  50 +.ifnc \called_from, exception
  51 +       st.as   r9, [sp, -10]   ; save r9 in it's final stack slot
  52 +       sub     sp, sp, 12      ; skip JLI, LDI, EI
  53 +
  54 +       PUSH    lp_count
  55 +       PUSHAX  lp_start
  56 +       PUSHAX  lp_end
  57 +       PUSH    blink
  58 +
  59 +       PUSH    r11
  60 +       PUSH    r10
  61 +
  62 +       sub     sp, sp, 4       ; skip r9
  63 +
  64 +       PUSH    r8
  65 +       PUSH    r7
  66 +       PUSH    r6
  67 +       PUSH    r5
  68 +       PUSH    r4
  69 +       PUSH    r3
  70 +       PUSH    r2
  71 +       PUSH    r1
  72 +       PUSH    r0
  73 +.endif
  74 +#endif
  75 +
  76  #ifdef CONFIG_ARC_HAS_ACCL_REGS
  77         PUSH    r59
  78         PUSH    r58
  79 @@ -86,6 +113,33 @@
  80         POP     r59
  81  #endif
  82
  83 +#ifdef CONFIG_ARC_IRQ_NO_AUTOSAVE
  84 +.ifnc \called_from, exception
  85 +       POP     r0
  86 +       POP     r1
  87 +       POP     r2
  88 +       POP     r3
  89 +       POP     r4
  90 +       POP     r5
  91 +       POP     r6
  92 +       POP     r7
  93 +       POP     r8
  94 +       POP     r9
  95 +       POP     r10
  96 +       POP     r11
  97 +
  98 +       POP     blink
  99 +       POPAX   lp_end
 100 +       POPAX   lp_start
 101 +
 102 +       POP     r9
 103 +       mov     lp_count, r9
 104 +
 105 +       add     sp, sp, 12      ; skip JLI, LDI, EI
 106 +       ld.as   r9, [sp, -10]   ; reload r9 which got clobbered
 107 +.endif
 108 +#endif
 109 +
 110  .endm
 111
 112  /*------------------------------------------------------------------------*/
 113 diff --git a/arch/arc/kernel/entry-arcv2.S b/arch/arc/kernel/entry-arcv2.S
 114 index cc558a25b8fa..562089d62d9d 100644
 115 --- a/arch/arc/kernel/entry-arcv2.S
 116 +++ b/arch/arc/kernel/entry-arcv2.S
 117 @@ -209,7 +209,9 @@ restore_regs:
 118  ;####### Return from Intr #######
 119
 120  debug_marker_l1:
 121 -       bbit1.nt r0, STATUS_DE_BIT, .Lintr_ret_to_delay_slot
 122 +       ; bbit1.nt r0, STATUS_DE_BIT, .Lintr_ret_to_delay_slot
 123 +       btst    r0, STATUS_DE_BIT               ; Z flag set if bit clear
 124 +       bnz     .Lintr_ret_to_delay_slot        ; branch if STATUS_DE_BIT set
 125
 126  .Lisr_ret_fast_path:
 127         ; Handle special case #1: (Entry via Exception, Return via IRQ)
 128 diff --git a/arch/arc/kernel/intc-arcv2.c b/arch/arc/kernel/intc-arcv2.c
 129 index 067ea362fb3e..cf18b3e5a934 100644
 130 --- a/arch/arc/kernel/intc-arcv2.c
 131 +++ b/arch/arc/kernel/intc-arcv2.c
 132 @@ -49,11 +49,13 @@ void arc_init_IRQ(void)
 133
 134         *(unsigned int *)&ictrl = 0;
 135
 136 +#ifndef CONFIG_ARC_IRQ_NO_AUTOSAVE
 137         ictrl.save_nr_gpr_pairs = 6;    /* r0 to r11 (r12 saved manually) */
 138         ictrl.save_blink = 1;
 139         ictrl.save_lp_regs = 1;         /* LP_COUNT, LP_START, LP_END */
 140         ictrl.save_u_to_u = 0;          /* user ctxt saved on kernel stack */
 141         ictrl.save_idx_regs = 1;        /* JLI, LDI, EI */
 142 +#endif
 143
 144         WRITE_AUX(AUX_IRQ_CTRL, ictrl);
 145
 146 diff --git a/arch/arc/plat-hsdk/Kconfig b/arch/arc/plat-hsdk/Kconfig
 147 index 9356753c2ed8..c285a83cbf08 100644
 148 --- a/arch/arc/plat-hsdk/Kconfig
 149 +++ b/arch/arc/plat-hsdk/Kconfig
 150 @@ -9,6 +9,7 @@ menuconfig ARC_SOC_HSDK
 151         bool "ARC HS Development Kit SOC"
 152         depends on ISA_ARCV2
 153         select ARC_HAS_ACCL_REGS
 154 +       select ARC_IRQ_NO_AUTOSAVE
 155         select CLK_HSDK
 156         select RESET_HSDK
 157         select MIGHT_HAVE_PCI
 158 --
 159 2.19.1
 160