From 824122a319d827d42aeb4646a3bf639937fdb2ce Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Tue, 1 Apr 2014 00:14:41 +0100 Subject: MIPS: DEC/SNI: O32 wrapper stack switching fixes Commit 231a35d37293ab88d325a9cb94e5474c156282c0 [[MIPS] RM: Collected changes] broke DECstation support by introducing an incompatible copy of arch/mips/dec/prom/call_o32.S in arch/mips/fw/lib/, built unconditionally. The copy happens to land earlier of the two among the modules used in the link and is therefore chosen for the DECstation rather than the intended original. As a result random kernel data is corrupted because a pointer to the "%s" formatted output template is used as a temporary stack pointer rather than being passed down to prom_printf. This also explains why prom_printf still works, up to a point -- the next argument is the actual string to output so it works just fine as the output template until enough kernel data has been corrupted to cause a crash. This change adjusts the modified wrapper in arch/mips/fw/lib/call_o32.S to let callers request no stack switching by passing a null temporary stack pointer in $a1, reworks the DECstation callers to work with the updated interface and removes the old copy from arch/mips/dec/prom/call_o32.S. A few minor readability adjustments are included as well, most importantly O32_SZREG is now used throughout where applicable rather than hardcoded multiplies of 4 and $fp is used to access the argument save area as a more usual register to operate the stack with rather than $s0. Finally an update is made to the temporary stack space used by the SNI platform to guarantee 8-byte alignment as per o32 requirements. Signed-off-by: Maciej W. Rozycki Cc: Thomas Bogendoerfer Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/6668/ Signed-off-by: Ralf Baechle --- arch/mips/dec/prom/Makefile | 1 - arch/mips/dec/prom/call_o32.S | 89 ------------------------------------------- 2 files changed, 90 deletions(-) delete mode 100644 arch/mips/dec/prom/call_o32.S (limited to 'arch/mips/dec/prom') diff --git a/arch/mips/dec/prom/Makefile b/arch/mips/dec/prom/Makefile index 064ae7a76bdc..ae73e42ac20b 100644 --- a/arch/mips/dec/prom/Makefile +++ b/arch/mips/dec/prom/Makefile @@ -6,4 +6,3 @@ lib-y += init.o memory.o cmdline.o identify.o console.o lib-$(CONFIG_32BIT) += locore.o -lib-$(CONFIG_64BIT) += call_o32.o diff --git a/arch/mips/dec/prom/call_o32.S b/arch/mips/dec/prom/call_o32.S deleted file mode 100644 index 8c8498159e43..000000000000 --- a/arch/mips/dec/prom/call_o32.S +++ /dev/null @@ -1,89 +0,0 @@ -/* - * O32 interface for the 64 (or N32) ABI. - * - * Copyright (C) 2002 Maciej W. Rozycki - * - * 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 -#include - -/* Maximum number of arguments supported. Must be even! */ -#define O32_ARGC 32 -/* Number of static registers we save. */ -#define O32_STATC 11 -/* Frame size for both of the above. */ -#define O32_FRAMESZ (4 * O32_ARGC + SZREG * O32_STATC) - - .text - -/* - * O32 function call dispatcher, for interfacing 32-bit ROM routines. - * - * The standard 64 (N32) calling sequence is supported, with a0 - * holding a function pointer, a1-a7 -- its first seven arguments - * and the stack -- remaining ones (up to O32_ARGC, including a1-a7). - * Static registers, gp and fp are preserved, v0 holds a result. - * This code relies on the called o32 function for sp and ra - * restoration and thus both this dispatcher and the current stack - * have to be placed in a KSEGx (or KUSEG) address space. Any - * pointers passed have to point to addresses within one of these - * spaces as well. - */ -NESTED(call_o32, O32_FRAMESZ, ra) - REG_SUBU sp,O32_FRAMESZ - - REG_S ra,O32_FRAMESZ-1*SZREG(sp) - REG_S fp,O32_FRAMESZ-2*SZREG(sp) - REG_S gp,O32_FRAMESZ-3*SZREG(sp) - REG_S s7,O32_FRAMESZ-4*SZREG(sp) - REG_S s6,O32_FRAMESZ-5*SZREG(sp) - REG_S s5,O32_FRAMESZ-6*SZREG(sp) - REG_S s4,O32_FRAMESZ-7*SZREG(sp) - REG_S s3,O32_FRAMESZ-8*SZREG(sp) - REG_S s2,O32_FRAMESZ-9*SZREG(sp) - REG_S s1,O32_FRAMESZ-10*SZREG(sp) - REG_S s0,O32_FRAMESZ-11*SZREG(sp) - - move jp,a0 - - sll a0,a1,zero - sll a1,a2,zero - sll a2,a3,zero - sll a3,a4,zero - sw a5,0x10(sp) - sw a6,0x14(sp) - sw a7,0x18(sp) - - PTR_LA t0,O32_FRAMESZ(sp) - PTR_LA t1,0x1c(sp) - li t2,O32_ARGC-7 -1: - lw t3,(t0) - REG_ADDU t0,SZREG - sw t3,(t1) - REG_SUBU t2,1 - REG_ADDU t1,4 - bnez t2,1b - - jalr jp - - REG_L s0,O32_FRAMESZ-11*SZREG(sp) - REG_L s1,O32_FRAMESZ-10*SZREG(sp) - REG_L s2,O32_FRAMESZ-9*SZREG(sp) - REG_L s3,O32_FRAMESZ-8*SZREG(sp) - REG_L s4,O32_FRAMESZ-7*SZREG(sp) - REG_L s5,O32_FRAMESZ-6*SZREG(sp) - REG_L s6,O32_FRAMESZ-5*SZREG(sp) - REG_L s7,O32_FRAMESZ-4*SZREG(sp) - REG_L gp,O32_FRAMESZ-3*SZREG(sp) - REG_L fp,O32_FRAMESZ-2*SZREG(sp) - REG_L ra,O32_FRAMESZ-1*SZREG(sp) - - REG_ADDU sp,O32_FRAMESZ - jr ra -END(call_o32) -- cgit v1.2.3