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Thu, 19 Nov 2020 16:05:01 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Thu, 19 Nov 2020 17:05:03 +0100 (CET) Date: Thu, 19 Nov 2020 17:05:00 +0100 From: Oleg Nesterov To: Benjamin Herrenschmidt , Madhavan Srinivasan , Michael Ellerman , Paul Mackerras Subject: Re: [PATCH v3 2/2] powerpc/ptrace: Hard wire PT_SOFTE value to 1 in gpr_get() too Message-ID: <20201119160500.GC5188@redhat.com> References: <20201119160154.GA5183@redhat.com> <20201119160247.GB5188@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201119160247.GB5188@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Christophe Leroy , "Aneesh Kumar K.V" , linux-kernel@vger.kernel.org, Nicholas Piggin , Jan Kratochvil , Al Viro , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 11/19, Oleg Nesterov wrote: > > This is not consistent and this breaks the user-regs-peekpoke test > from https://sourceware.org/systemtap/wiki/utrace/tests/ See the test-case below. Oleg. /* Test case for PTRACE_SETREGS modifying the requested ragisters. x86* counterpart of the s390* testcase `user-area-access.c'. This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely. */ /* FIXME: EFLAGS should be tested restricted on the appropriate bits. */ #define _GNU_SOURCE 1 #if defined __powerpc__ || defined __sparc__ # define user_regs_struct pt_regs #endif #ifdef __ia64__ #define ia64_fpreg ia64_fpreg_DISABLE #define pt_all_user_regs pt_all_user_regs_DISABLE #endif /* __ia64__ */ #include #ifdef __ia64__ #undef ia64_fpreg #undef pt_all_user_regs #endif /* __ia64__ */ #include #include #include #if defined __i386__ || defined __x86_64__ #include #endif #include #include #include #include #include #include #include #include #include #include #include #include /* ia64 has PTRACE_SETREGS but it has no USER_REGS_STRUCT. */ #if !defined PTRACE_SETREGS || defined __ia64__ int main (void) { return 77; } #else /* PTRACE_SETREGS */ /* The minimal alignment we use for the random access ranges. */ #define REGALIGN (sizeof (long)) static pid_t child; static void cleanup (void) { if (child > 0) kill (child, SIGKILL); child = 0; } static void handler_fail (int signo) { cleanup (); signal (SIGABRT, SIG_DFL); abort (); } int main (void) { long l; int status, i; pid_t pid; union { struct user_regs_struct user; unsigned char byte[sizeof (struct user_regs_struct)]; } u, u2; int start; setbuf (stdout, NULL); atexit (cleanup); signal (SIGABRT, handler_fail); signal (SIGALRM, handler_fail); signal (SIGINT, handler_fail); i = alarm (10); assert (i == 0); child = fork (); switch (child) { case -1: assert_perror (errno); assert (0); case 0: l = ptrace (PTRACE_TRACEME, 0, NULL, NULL); assert (l == 0); // Prevent rt_sigprocmask() call called by glibc after raise(). syscall (__NR_tkill, getpid (), SIGSTOP); assert (0); default: break; } pid = waitpid (child, &status, 0); assert (pid == child); assert (WIFSTOPPED (status)); assert (WSTOPSIG (status) == SIGSTOP); /* Fetch U2 from the inferior. */ errno = 0; # ifdef __sparc__ l = ptrace (PTRACE_GETREGS, child, &u2.user, NULL); # else l = ptrace (PTRACE_GETREGS, child, NULL, &u2.user); # endif assert_perror (errno); assert (l == 0); /* Initialize U with a pattern. */ for (i = 0; i < sizeof u.byte; i++) u.byte[i] = i; #ifdef __x86_64__ /* non-EFLAGS modifications fail with EIO, EFLAGS gets back different. */ u.user.eflags = u2.user.eflags; u.user.cs = u2.user.cs; u.user.ds = u2.user.ds; u.user.es = u2.user.es; u.user.fs = u2.user.fs; u.user.gs = u2.user.gs; u.user.ss = u2.user.ss; u.user.fs_base = u2.user.fs_base; u.user.gs_base = u2.user.gs_base; /* RHEL-4 refuses to set too high (and invalid) PC values. */ u.user.rip = (unsigned long) handler_fail; /* 2.6.25 always truncates and sign-extends orig_rax. */ u.user.orig_rax = (int) u.user.orig_rax; #endif /* __x86_64__ */ #ifdef __i386__ /* These values get back different. */ u.user.xds = u2.user.xds; u.user.xes = u2.user.xes; u.user.xfs = u2.user.xfs; u.user.xgs = u2.user.xgs; u.user.xcs = u2.user.xcs; u.user.eflags = u2.user.eflags; u.user.xss = u2.user.xss; /* RHEL-4 refuses to set too high (and invalid) PC values. */ u.user.eip = (unsigned long) handler_fail; #endif /* __i386__ */ #ifdef __powerpc__ /* These fields are constrained. */ u.user.msr = u2.user.msr; # ifdef __powerpc64__ u.user.softe = u2.user.softe; # else u.user.mq = u2.user.mq; # endif /* __powerpc64__ */ u.user.trap = u2.user.trap; u.user.dar = u2.user.dar; u.user.dsisr = u2.user.dsisr; u.user.result = u2.user.result; #endif /* __powerpc__ */ /* Poke U. */ # ifdef __sparc__ l = ptrace (PTRACE_SETREGS, child, &u.user, NULL); # else l = ptrace (PTRACE_SETREGS, child, NULL, &u.user); # endif assert (l == 0); /* Peek into U2. */ # ifdef __sparc__ l = ptrace (PTRACE_GETREGS, child, &u2.user, NULL); # else l = ptrace (PTRACE_GETREGS, child, NULL, &u2.user); # endif assert (l == 0); /* Verify it matches. */ if (memcmp (&u.user, &u2.user, sizeof u.byte) != 0) { for (start = 0; start + REGALIGN <= sizeof u.byte; start += REGALIGN) if (*(unsigned long *) (u.byte + start) != *(unsigned long *) (u2.byte + start)) printf ("\ mismatch at offset %#x: SETREGS wrote %lx GETREGS read %lx\n", start, *(unsigned long *) (u.byte + start), *(unsigned long *) (u2.byte + start)); return 1; } /* Reverse the pattern. */ for (i = 0; i < sizeof u.byte; i++) u.byte[i] ^= -1; #ifdef __x86_64__ /* non-EFLAGS modifications fail with EIO, EFLAGS gets back different. */ u.user.eflags = u2.user.eflags; u.user.cs = u2.user.cs; u.user.ds = u2.user.ds; u.user.es = u2.user.es; u.user.fs = u2.user.fs; u.user.gs = u2.user.gs; u.user.ss = u2.user.ss; u.user.fs_base = u2.user.fs_base; u.user.gs_base = u2.user.gs_base; /* RHEL-4 refuses to set too high (and invalid) PC values. */ u.user.rip = (unsigned long) handler_fail; /* 2.6.25 always truncates and sign-extends orig_rax. */ u.user.orig_rax = (int) u.user.orig_rax; #endif /* __x86_64__ */ #ifdef __i386__ /* These values get back different. */ u.user.xds = u2.user.xds; u.user.xes = u2.user.xes; u.user.xfs = u2.user.xfs; u.user.xgs = u2.user.xgs; u.user.xcs = u2.user.xcs; u.user.eflags = u2.user.eflags; u.user.xss = u2.user.xss; /* RHEL-4 refuses to set too high (and invalid) PC values. */ u.user.eip = (unsigned long) handler_fail; #endif /* __i386__ */ #ifdef __powerpc__ /* These fields are constrained. */ u.user.msr = u2.user.msr; # ifdef __powerpc64__ u.user.softe = u2.user.softe; # else u.user.mq = u2.user.mq; # endif /* __powerpc64__ */ u.user.trap = u2.user.trap; u.user.dar = u2.user.dar; u.user.dsisr = u2.user.dsisr; u.user.result = u2.user.result; #endif /* __powerpc__ */ /* Poke U. */ # ifdef __sparc__ l = ptrace (PTRACE_SETREGS, child, &u.user, NULL); # else l = ptrace (PTRACE_SETREGS, child, NULL, &u.user); # endif assert (l == 0); /* Peek into U2. */ # ifdef __sparc__ l = ptrace (PTRACE_GETREGS, child, &u2.user, NULL); # else l = ptrace (PTRACE_GETREGS, child, NULL, &u2.user); # endif assert (l == 0); /* Verify it matches. */ if (memcmp (&u.user, &u2.user, sizeof u.byte) != 0) { for (start = 0; start + REGALIGN <= sizeof u.byte; start += REGALIGN) if (*(unsigned long *) (u.byte + start) != *(unsigned long *) (u2.byte + start)) printf ("\ mismatch at offset %#x: SETREGS wrote %lx GETREGS read %lx\n", start, *(unsigned long *) (u.byte + start), *(unsigned long *) (u2.byte + start)); return 1; } /* Now try poking arbitrary ranges and verifying it reads back right. We expect the U area is already a random enough pattern. */ for (start = 0; start + REGALIGN <= sizeof u.byte; start += REGALIGN) { for (i = start; i < start + REGALIGN; i++) u.byte[i]++; #ifdef __x86_64__ /* non-EFLAGS modifications fail with EIO, EFLAGS gets back different. */ u.user.eflags = u2.user.eflags; u.user.cs = u2.user.cs; u.user.ds = u2.user.ds; u.user.es = u2.user.es; u.user.fs = u2.user.fs; u.user.gs = u2.user.gs; u.user.ss = u2.user.ss; u.user.fs_base = u2.user.fs_base; u.user.gs_base = u2.user.gs_base; /* RHEL-4 refuses to set too high (and invalid) PC values. */ u.user.rip = (unsigned long) handler_fail; /* 2.6.25 always truncates and sign-extends orig_rax. */ u.user.orig_rax = (int) u.user.orig_rax; #endif /* __x86_64__ */ #ifdef __i386__ /* These values get back different. */ u.user.xds = u2.user.xds; u.user.xes = u2.user.xes; u.user.xfs = u2.user.xfs; u.user.xgs = u2.user.xgs; u.user.xcs = u2.user.xcs; u.user.eflags = u2.user.eflags; u.user.xss = u2.user.xss; /* RHEL-4 refuses to set too high (and invalid) PC values. */ u.user.eip = (unsigned long) handler_fail; #endif /* __i386__ */ #ifdef __powerpc__ /* These fields are constrained. */ u.user.msr = u2.user.msr; # ifdef __powerpc64__ u.user.softe = u2.user.softe; # else u.user.mq = u2.user.mq; # endif /* __powerpc64__ */ u.user.trap = u2.user.trap; u.user.dar = u2.user.dar; u.user.dsisr = u2.user.dsisr; u.user.result = u2.user.result; if (start > offsetof (struct pt_regs, ccr)) break; #endif /* __powerpc__ */ /* Poke U. */ l = ptrace (PTRACE_POKEUSER, child, (void *) (unsigned long) start, (void *) *(unsigned long *) (u.byte + start)); if (l != 0) error (1, errno, "PTRACE_POKEUSER at %x", start); /* Peek into U2. */ # ifdef __sparc__ l = ptrace (PTRACE_GETREGS, child, &u2.user, NULL); # else l = ptrace (PTRACE_GETREGS, child, NULL, &u2.user); # endif assert (l == 0); /* Verify it matches. */ if (memcmp (&u.user, &u2.user, sizeof u.byte) != 0) { printf ("mismatch at offset %#x: poked %lx but GETREGS read %lx\n", start, *(unsigned long *) (u.byte + start), *(unsigned long *) (u2.byte + start)); return 1; } } /* Now try peeking arbitrary ranges and verifying it is the same. We expect the U area is already a random enough pattern. */ for (start = 0; start + REGALIGN <= sizeof u.byte; start += REGALIGN) { /* Peek for the U comparation. */ errno = 0; l = ptrace (PTRACE_PEEKUSER, child, (void *) (unsigned long) start, NULL); assert_perror (errno); /* Verify it matches. */ if (*(unsigned long *) (u.byte + start) != l) { printf ("mismatch at offset %#x: poked %lx but peeked %lx\n", start, *(unsigned long *) (u.byte + start), l); return 1; } } return 0; } #endif /* PTRACE_SETREGS */