From fab5db97e44f76461f76b24adfa8ccb14d4df498 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Wed, 7 Jun 2006 16:14:40 +1000 Subject: [PATCH] powerpc: Implement support for setting little-endian mode via prctl This adds the PowerPC part of the code to allow processes to change their endian mode via prctl. This also extends the alignment exception handler to be able to fix up alignment exceptions that occur in little-endian mode, both for "PowerPC" little-endian and true little-endian. We always enter signal handlers in big-endian mode -- the support for little-endian mode does not amount to the creation of a little-endian user/kernel ABI. If the signal handler returns, the endian mode is restored to what it was when the signal was delivered. We have two new kernel CPU feature bits, one for PPC little-endian and one for true little-endian. Most of the classic 32-bit processors support PPC little-endian, and this is reflected in the CPU feature table. There are two corresponding feature bits reported to userland in the AT_HWCAP aux vector entry. This is based on an earlier patch by Anton Blanchard. Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/process.c | 44 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) (limited to 'arch/powerpc/kernel/process.c') diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 2dd47d2dd99..2d35d83961b 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -708,6 +708,50 @@ int get_fpexc_mode(struct task_struct *tsk, unsigned long adr) return put_user(val, (unsigned int __user *) adr); } +int set_endian(struct task_struct *tsk, unsigned int val) +{ + struct pt_regs *regs = tsk->thread.regs; + + if ((val == PR_ENDIAN_LITTLE && !cpu_has_feature(CPU_FTR_REAL_LE)) || + (val == PR_ENDIAN_PPC_LITTLE && !cpu_has_feature(CPU_FTR_PPC_LE))) + return -EINVAL; + + if (regs == NULL) + return -EINVAL; + + if (val == PR_ENDIAN_BIG) + regs->msr &= ~MSR_LE; + else if (val == PR_ENDIAN_LITTLE || val == PR_ENDIAN_PPC_LITTLE) + regs->msr |= MSR_LE; + else + return -EINVAL; + + return 0; +} + +int get_endian(struct task_struct *tsk, unsigned long adr) +{ + struct pt_regs *regs = tsk->thread.regs; + unsigned int val; + + if (!cpu_has_feature(CPU_FTR_PPC_LE) && + !cpu_has_feature(CPU_FTR_REAL_LE)) + return -EINVAL; + + if (regs == NULL) + return -EINVAL; + + if (regs->msr & MSR_LE) { + if (cpu_has_feature(CPU_FTR_REAL_LE)) + val = PR_ENDIAN_LITTLE; + else + val = PR_ENDIAN_PPC_LITTLE; + } else + val = PR_ENDIAN_BIG; + + return put_user(val, (unsigned int __user *)adr); +} + #define TRUNC_PTR(x) ((typeof(x))(((unsigned long)(x)) & 0xffffffff)) int sys_clone(unsigned long clone_flags, unsigned long usp, -- cgit v1.2.3-70-g09d2 From e9370ae15dc2f8ba1e1889ce26f13cda565b6ecb Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Wed, 7 Jun 2006 16:15:39 +1000 Subject: [PATCH] powerpc: Implement PR_[GS]ET_UNALIGN prctls for powerpc This gives the ability to control whether alignment exceptions get fixed up or reported to the process as a SIGBUS, using the existing PR_SET_UNALIGN and PR_GET_UNALIGN prctls. We do not implement the option of logging a message on alignment exceptions. Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/process.c | 11 +++++++++++ arch/powerpc/kernel/traps.c | 6 ++++-- include/asm-powerpc/processor.h | 7 +++++++ 3 files changed, 22 insertions(+), 2 deletions(-) (limited to 'arch/powerpc/kernel/process.c') diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 2d35d83961b..e4732459c48 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -752,6 +752,17 @@ int get_endian(struct task_struct *tsk, unsigned long adr) return put_user(val, (unsigned int __user *)adr); } +int set_unalign_ctl(struct task_struct *tsk, unsigned int val) +{ + tsk->thread.align_ctl = val; + return 0; +} + +int get_unalign_ctl(struct task_struct *tsk, unsigned long adr) +{ + return put_user(tsk->thread.align_ctl, (unsigned int __user *)adr); +} + #define TRUNC_PTR(x) ((typeof(x))(((unsigned long)(x)) & 0xffffffff)) int sys_clone(unsigned long clone_flags, unsigned long usp, diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index 03def571549..91a6e04d974 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -805,9 +805,11 @@ void __kprobes program_check_exception(struct pt_regs *regs) void alignment_exception(struct pt_regs *regs) { - int fixed; + int fixed = 0; - fixed = fix_alignment(regs); + /* we don't implement logging of alignment exceptions */ + if (!(current->thread.align_ctl & PR_UNALIGN_SIGBUS)) + fixed = fix_alignment(regs); if (fixed == 1) { regs->nip += 4; /* skip over emulated instruction */ diff --git a/include/asm-powerpc/processor.h b/include/asm-powerpc/processor.h index fa616326815..d2c2c95f913 100644 --- a/include/asm-powerpc/processor.h +++ b/include/asm-powerpc/processor.h @@ -149,6 +149,7 @@ struct thread_struct { unsigned int val; /* Floating point status */ } fpscr; int fpexc_mode; /* floating-point exception mode */ + unsigned int align_ctl; /* alignment handling control */ #ifdef CONFIG_PPC64 unsigned long start_tb; /* Start purr when proc switched in */ unsigned long accum_tb; /* Total accumilated purr for process */ @@ -217,6 +218,12 @@ extern int set_fpexc_mode(struct task_struct *tsk, unsigned int val); extern int get_endian(struct task_struct *tsk, unsigned long adr); extern int set_endian(struct task_struct *tsk, unsigned int val); +#define GET_UNALIGN_CTL(tsk, adr) get_unalign_ctl((tsk), (adr)) +#define SET_UNALIGN_CTL(tsk, val) set_unalign_ctl((tsk), (val)) + +extern int get_unalign_ctl(struct task_struct *tsk, unsigned long adr); +extern int set_unalign_ctl(struct task_struct *tsk, unsigned int val); + static inline unsigned int __unpack_fe01(unsigned long msr_bits) { return ((msr_bits & MSR_FE0) >> 10) | ((msr_bits & MSR_FE1) >> 8); -- cgit v1.2.3-70-g09d2