From 377fad3acbb7e94ab9942a74e0d9ede8eeb2f039 Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Sun, 6 May 2007 14:51:25 -0700 Subject: [PATCH] uml: kernel segfaults should dump proper registers If there's a segfault inside the kernel, we want a dump of the registers at the point of the segfault, not the registers at the point of calling panic or the last userspace registers. sig_handler_common_skas now uses a static register set in the case of a SIGSEGV to avoid messing up the process registers if the segfault turns out to be non-fatal. The architecture sigcontext-to-pt_regs copying code was repurposed to copy data out of the SEGV stack frame. Signed-off-by: Jeff Dike Cc: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/include/common-offsets.h | 2 ++ arch/um/include/kern_util.h | 2 ++ arch/um/kernel/trap.c | 10 +++++--- arch/um/os-Linux/skas/trap.c | 15 ++++++++++-- arch/um/sys-i386/signal.c | 41 +++++++++++++++++++------------- arch/um/sys-x86_64/signal.c | 30 +++++++++++++++++++++++ 6 files changed, 78 insertions(+), 22 deletions(-) diff --git a/arch/um/include/common-offsets.h b/arch/um/include/common-offsets.h index 461175f8b1d9..5593a8027083 100644 --- a/arch/um/include/common-offsets.h +++ b/arch/um/include/common-offsets.h @@ -24,5 +24,7 @@ DEFINE(UM_ELF_CLASS, ELF_CLASS); DEFINE(UM_ELFCLASS32, ELFCLASS32); DEFINE(UM_ELFCLASS64, ELFCLASS64); +DEFINE(UM_NR_CPUS, NR_CPUS); + /* For crypto assembler code. */ DEFINE(crypto_tfm_ctx_offset, offsetof(struct crypto_tfm, __crt_ctx)); diff --git a/arch/um/include/kern_util.h b/arch/um/include/kern_util.h index 092a2841556f..50a49691e0e6 100644 --- a/arch/um/include/kern_util.h +++ b/arch/um/include/kern_util.h @@ -115,4 +115,6 @@ extern void time_init_kern(void); extern int __cant_sleep(void); extern void sigio_handler(int sig, union uml_pt_regs *regs); +extern void copy_sc(union uml_pt_regs *regs, void *from); + #endif diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c index c3e62e634c0a..0c467fa08870 100644 --- a/arch/um/kernel/trap.c +++ b/arch/um/kernel/trap.c @@ -170,8 +170,10 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, flush_tlb_kernel_vm(); return 0; } - else if(current->mm == NULL) - panic("Segfault with no mm"); + else if(current->mm == NULL) { + show_regs(container_of(regs, struct pt_regs, regs)); + panic("Segfault with no mm"); + } if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi)) err = handle_page_fault(address, ip, is_write, is_user, &si.si_code); @@ -194,9 +196,11 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user, else if(!is_user && arch_fixup(ip, regs)) return 0; - if(!is_user) + if(!is_user) { + show_regs(container_of(regs, struct pt_regs, regs)); panic("Kernel mode fault at addr 0x%lx, ip 0x%lx", address, ip); + } if (err == -EACCES) { si.si_signo = SIGBUS; diff --git a/arch/um/os-Linux/skas/trap.c b/arch/um/os-Linux/skas/trap.c index 6a20d08caf91..5110eff51b90 100644 --- a/arch/um/os-Linux/skas/trap.c +++ b/arch/um/os-Linux/skas/trap.c @@ -15,6 +15,8 @@ #include "sysdep/ptrace_user.h" #include "os.h" +static union uml_pt_regs ksig_regs[UM_NR_CPUS]; + void sig_handler_common_skas(int sig, void *sc_ptr) { struct sigcontext *sc = sc_ptr; @@ -27,10 +29,19 @@ void sig_handler_common_skas(int sig, void *sc_ptr) * the process will die. * XXX Figure out why this is better than SA_NODEFER */ - if(sig == SIGSEGV) + if(sig == SIGSEGV) { change_sig(SIGSEGV, 1); + /* For segfaults, we want the data from the + * sigcontext. In this case, we don't want to mangle + * the process registers, so use a static set of + * registers. For other signals, the process + * registers are OK. + */ + r = &ksig_regs[cpu()]; + copy_sc(r, sc_ptr); + } + else r = TASK_REGS(get_current()); - r = TASK_REGS(get_current()); save_user = r->skas.is_user; r->skas.is_user = 0; if ( sig == SIGFPE || sig == SIGSEGV || diff --git a/arch/um/sys-i386/signal.c b/arch/um/sys-i386/signal.c index 42ecf8e8ad08..1cbf95f6858a 100644 --- a/arch/um/sys-i386/signal.c +++ b/arch/um/sys-i386/signal.c @@ -18,6 +18,28 @@ #include "skas.h" +void copy_sc(union uml_pt_regs *regs, void *from) +{ + struct sigcontext *sc = from; + + REGS_GS(regs->skas.regs) = sc->gs; + REGS_FS(regs->skas.regs) = sc->fs; + REGS_ES(regs->skas.regs) = sc->es; + REGS_DS(regs->skas.regs) = sc->ds; + REGS_EDI(regs->skas.regs) = sc->edi; + REGS_ESI(regs->skas.regs) = sc->esi; + REGS_EBP(regs->skas.regs) = sc->ebp; + REGS_SP(regs->skas.regs) = sc->esp; + REGS_EBX(regs->skas.regs) = sc->ebx; + REGS_EDX(regs->skas.regs) = sc->edx; + REGS_ECX(regs->skas.regs) = sc->ecx; + REGS_EAX(regs->skas.regs) = sc->eax; + REGS_IP(regs->skas.regs) = sc->eip; + REGS_CS(regs->skas.regs) = sc->cs; + REGS_EFLAGS(regs->skas.regs) = sc->eflags; + REGS_SS(regs->skas.regs) = sc->ss; +} + static int copy_sc_from_user_skas(struct pt_regs *regs, struct sigcontext __user *from) { @@ -30,25 +52,10 @@ static int copy_sc_from_user_skas(struct pt_regs *regs, if(err) return err; - REGS_GS(regs->regs.skas.regs) = sc.gs; - REGS_FS(regs->regs.skas.regs) = sc.fs; - REGS_ES(regs->regs.skas.regs) = sc.es; - REGS_DS(regs->regs.skas.regs) = sc.ds; - REGS_EDI(regs->regs.skas.regs) = sc.edi; - REGS_ESI(regs->regs.skas.regs) = sc.esi; - REGS_EBP(regs->regs.skas.regs) = sc.ebp; - REGS_SP(regs->regs.skas.regs) = sc.esp; - REGS_EBX(regs->regs.skas.regs) = sc.ebx; - REGS_EDX(regs->regs.skas.regs) = sc.edx; - REGS_ECX(regs->regs.skas.regs) = sc.ecx; - REGS_EAX(regs->regs.skas.regs) = sc.eax; - REGS_IP(regs->regs.skas.regs) = sc.eip; - REGS_CS(regs->regs.skas.regs) = sc.cs; - REGS_EFLAGS(regs->regs.skas.regs) = sc.eflags; - REGS_SS(regs->regs.skas.regs) = sc.ss; + copy_sc(®s->regs, &sc); err = restore_fp_registers(userspace_pid[0], fpregs); - if(err < 0){ + if(err < 0) { printk("copy_sc_from_user_skas - PTRACE_SETFPREGS failed, " "errno = %d\n", -err); return err; diff --git a/arch/um/sys-x86_64/signal.c b/arch/um/sys-x86_64/signal.c index 068006213598..fe8ec04d35bb 100644 --- a/arch/um/sys-x86_64/signal.c +++ b/arch/um/sys-x86_64/signal.c @@ -20,6 +20,36 @@ #include "skas.h" +void copy_sc(union uml_pt_regs *regs, void *from) +{ + struct sigcontext *sc = from; + +#define GETREG(regs, regno, sc, regname) \ + (regs)->skas.regs[(regno) / sizeof(unsigned long)] = (sc)->regname + + GETREG(regs, R8, sc, r8); + GETREG(regs, R9, sc, r9); + GETREG(regs, R10, sc, r10); + GETREG(regs, R11, sc, r11); + GETREG(regs, R12, sc, r12); + GETREG(regs, R13, sc, r13); + GETREG(regs, R14, sc, r14); + GETREG(regs, R15, sc, r15); + GETREG(regs, RDI, sc, rdi); + GETREG(regs, RSI, sc, rsi); + GETREG(regs, RBP, sc, rbp); + GETREG(regs, RBX, sc, rbx); + GETREG(regs, RDX, sc, rdx); + GETREG(regs, RAX, sc, rax); + GETREG(regs, RCX, sc, rcx); + GETREG(regs, RSP, sc, rsp); + GETREG(regs, RIP, sc, rip); + GETREG(regs, EFLAGS, sc, eflags); + GETREG(regs, CS, sc, cs); + +#undef GETREG +} + static int copy_sc_from_user_skas(struct pt_regs *regs, struct sigcontext __user *from) {