From b91e136cdf88e19e998dbf4631ead266de4b80b5 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 7 Apr 2011 21:56:04 +0000 Subject: [PATCH] powerpc: Use MSR_64BIT in sstep.c, fix kprobes on BOOK3E We check MSR_SF a lot in sstep.c, to decide if we need to emulate the truncation of values when running in 32-bit mode. Factor out that code into a helper, and convert it and the other uses to use MSR_64BIT. This fixes a bug on BOOK3E where kprobes would end up returning to a 32-bit address, because regs->nip was truncated, because (msr & MSR_SF) was false. Signed-off-by: Michael Ellerman Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/lib/sstep.c | 61 ++++++++++++++++++---------------------- 1 file changed, 27 insertions(+), 34 deletions(-) diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index ae5189ab0049..0e5e540c7778 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -44,6 +44,18 @@ extern int do_lxvd2x(int rn, unsigned long ea); extern int do_stxvd2x(int rn, unsigned long ea); #endif +/* + * Emulate the truncation of 64 bit values in 32-bit mode. + */ +static unsigned long truncate_if_32bit(unsigned long msr, unsigned long val) +{ +#ifdef __powerpc64__ + if ((msr & MSR_64BIT) == 0) + val &= 0xffffffffUL; +#endif + return val; +} + /* * Determine whether a conditional branch instruction would branch. */ @@ -90,11 +102,8 @@ static unsigned long __kprobes dform_ea(unsigned int instr, struct pt_regs *regs if (instr & 0x04000000) /* update forms */ regs->gpr[ra] = ea; } -#ifdef __powerpc64__ - if (!(regs->msr & MSR_SF)) - ea &= 0xffffffffUL; -#endif - return ea; + + return truncate_if_32bit(regs->msr, ea); } #ifdef __powerpc64__ @@ -113,9 +122,8 @@ static unsigned long __kprobes dsform_ea(unsigned int instr, struct pt_regs *reg if ((instr & 3) == 1) /* update forms */ regs->gpr[ra] = ea; } - if (!(regs->msr & MSR_SF)) - ea &= 0xffffffffUL; - return ea; + + return truncate_if_32bit(regs->msr, ea); } #endif /* __powerpc64 */ @@ -136,11 +144,8 @@ static unsigned long __kprobes xform_ea(unsigned int instr, struct pt_regs *regs if (do_update) /* update forms */ regs->gpr[ra] = ea; } -#ifdef __powerpc64__ - if (!(regs->msr & MSR_SF)) - ea &= 0xffffffffUL; -#endif - return ea; + + return truncate_if_32bit(regs->msr, ea); } /* @@ -466,7 +471,7 @@ static void __kprobes set_cr0(struct pt_regs *regs, int rd) regs->ccr = (regs->ccr & 0x0fffffff) | ((regs->xer >> 3) & 0x10000000); #ifdef __powerpc64__ - if (!(regs->msr & MSR_SF)) + if (!(regs->msr & MSR_64BIT)) val = (int) val; #endif if (val < 0) @@ -487,7 +492,7 @@ static void __kprobes add_with_carry(struct pt_regs *regs, int rd, ++val; regs->gpr[rd] = val; #ifdef __powerpc64__ - if (!(regs->msr & MSR_SF)) { + if (!(regs->msr & MSR_64BIT)) { val = (unsigned int) val; val1 = (unsigned int) val1; } @@ -570,8 +575,7 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr) if ((instr & 2) == 0) imm += regs->nip; regs->nip += 4; - if ((regs->msr & MSR_SF) == 0) - regs->nip &= 0xffffffffUL; + regs->nip = truncate_if_32bit(regs->msr, regs->nip); if (instr & 1) regs->link = regs->nip; if (branch_taken(instr, regs)) @@ -604,13 +608,9 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr) imm -= 0x04000000; if ((instr & 2) == 0) imm += regs->nip; - if (instr & 1) { - regs->link = regs->nip + 4; - if ((regs->msr & MSR_SF) == 0) - regs->link &= 0xffffffffUL; - } - if ((regs->msr & MSR_SF) == 0) - imm &= 0xffffffffUL; + if (instr & 1) + regs->link = truncate_if_32bit(regs->msr, regs->nip + 4); + imm = truncate_if_32bit(regs->msr, imm); regs->nip = imm; return 1; case 19: @@ -618,11 +618,8 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr) case 16: /* bclr */ case 528: /* bcctr */ imm = (instr & 0x400)? regs->ctr: regs->link; - regs->nip += 4; - if ((regs->msr & MSR_SF) == 0) { - regs->nip &= 0xffffffffUL; - imm &= 0xffffffffUL; - } + regs->nip = truncate_if_32bit(regs->msr, regs->nip + 4); + imm = truncate_if_32bit(regs->msr, imm); if (instr & 1) regs->link = regs->nip; if (branch_taken(instr, regs)) @@ -1616,11 +1613,7 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr) return 0; /* invoke DSI if -EFAULT? */ } instr_done: - regs->nip += 4; -#ifdef __powerpc64__ - if ((regs->msr & MSR_SF) == 0) - regs->nip &= 0xffffffffUL; -#endif + regs->nip = truncate_if_32bit(regs->msr, regs->nip + 4); return 1; logical_done: -- 2.30.2