From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:35820 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727170AbeJNXLs (ORCPT ); Sun, 14 Oct 2018 19:11:48 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, linux-mips@linux-mips.org, "Ralf Baechle" , "Maciej W. Rozycki" , "James Hogan" Date: Sun, 14 Oct 2018 16:25:41 +0100 Message-ID: Subject: [PATCH 3.16 306/366] MIPS: ptrace: Expose FIR register through FP regset In-Reply-To: Sender: stable-owner@vger.kernel.org List-ID: 3.16.60-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: "Maciej W. Rozycki" commit 71e909c0cdad28a1df1fa14442929e68615dee45 upstream. Correct commit 7aeb753b5353 ("MIPS: Implement task_user_regset_view.") and expose the FIR register using the unused 4 bytes at the end of the NT_PRFPREG regset. Without that register included clients cannot use the PTRACE_GETREGSET request to retrieve the complete FPU register set and have to resort to one of the older interfaces, either PTRACE_PEEKUSR or PTRACE_GETFPREGS, to retrieve the missing piece of data. Also the register is irreversibly missing from core dumps. This register is architecturally hardwired and read-only so the write path does not matter. Ignore data supplied on writes then. Fixes: 7aeb753b5353 ("MIPS: Implement task_user_regset_view.") Signed-off-by: James Hogan Signed-off-by: Maciej W. Rozycki Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/19273/ Signed-off-by: James Hogan Signed-off-by: Ben Hutchings --- arch/mips/kernel/ptrace.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) --- a/arch/mips/kernel/ptrace.c +++ b/arch/mips/kernel/ptrace.c @@ -481,7 +481,7 @@ static int fpr_get_msa(struct task_struc /* * Copy the floating-point context to the supplied NT_PRFPREG buffer. * Choose the appropriate helper for general registers, and then copy - * the FCSR register separately. + * the FCSR and FIR registers separately. */ static int fpr_get(struct task_struct *target, const struct user_regset *regset, @@ -489,6 +489,7 @@ static int fpr_get(struct task_struct *t void *kbuf, void __user *ubuf) { const int fcr31_pos = NUM_FPU_REGS * sizeof(elf_fpreg_t); + const int fir_pos = fcr31_pos + sizeof(u32); int err; if (sizeof(target->thread.fpu.fpr[0]) == sizeof(elf_fpreg_t)) @@ -501,6 +502,12 @@ static int fpr_get(struct task_struct *t err = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &target->thread.fpu.fcr31, fcr31_pos, fcr31_pos + sizeof(u32)); + if (err) + return err; + + err = user_regset_copyout(&pos, &count, &kbuf, &ubuf, + &boot_cpu_data.fpu_id, + fir_pos, fir_pos + sizeof(u32)); return err; } @@ -549,7 +556,8 @@ static int fpr_set_msa(struct task_struc /* * Copy the supplied NT_PRFPREG buffer to the floating-point context. * Choose the appropriate helper for general registers, and then copy - * the FCSR register separately. + * the FCSR register separately. Ignore the incoming FIR register + * contents though, as the register is read-only. * * We optimize for the case where `count % sizeof(elf_fpreg_t) == 0', * which is supposed to have been guaranteed by the kernel before @@ -563,6 +571,7 @@ static int fpr_set(struct task_struct *t const void *kbuf, const void __user *ubuf) { const int fcr31_pos = NUM_FPU_REGS * sizeof(elf_fpreg_t); + const int fir_pos = fcr31_pos + sizeof(u32); u32 fcr31; int err; @@ -590,6 +599,11 @@ static int fpr_set(struct task_struct *t ptrace_setfcr31(target, fcr31); } + if (count > 0) + err = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf, + fir_pos, + fir_pos + sizeof(u32)); + return err; }