| Message ID | 20121005105133.GP4625@n2100.arm.linux.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 10/05/2012 06:51 AM, Russell King - ARM Linux wrote: <snip switch out the might_fault __get_user for atomic probe_kernel_address related discussion> > Okay, this should fix the issue... I've only compile tested it so far. > Rob, as you have a way to trigger this easily, can you give this patch > a go and let me know if it solves your problem? Thanks. Russell, can you let me know the status of this patch? I don't see it in your tree, and I think I might have missed a followup patch from you? It seems to solve a real problem with in-kernel faults during the dump_mem in general, even beyond just an alignment fault. Jon.
On Tue, Oct 23, 2012 at 12:30:14PM -0400, Jon Masters wrote: > On 10/05/2012 06:51 AM, Russell King - ARM Linux wrote: > > <snip switch out the might_fault __get_user for atomic > probe_kernel_address related discussion> > > > Okay, this should fix the issue... I've only compile tested it so far. > > Rob, as you have a way to trigger this easily, can you give this patch > > a go and let me know if it solves your problem? Thanks. > > Russell, can you let me know the status of this patch? I don't see it in > your tree, and I think I might have missed a followup patch from you? It > seems to solve a real problem with in-kernel faults during the dump_mem > in general, even beyond just an alignment fault. I was waiting for someone to say "I saw a problem and it works"... Would be nice to have a Tested-by tag against it...
On 10/23/2012 12:58 PM, Russell King - ARM Linux wrote: > On Tue, Oct 23, 2012 at 12:30:14PM -0400, Jon Masters wrote: >> On 10/05/2012 06:51 AM, Russell King - ARM Linux wrote: >> >> <snip switch out the might_fault __get_user for atomic >> probe_kernel_address related discussion> >> >>> Okay, this should fix the issue... I've only compile tested it so far. >>> Rob, as you have a way to trigger this easily, can you give this patch >>> a go and let me know if it solves your problem? Thanks. >> >> Russell, can you let me know the status of this patch? I don't see it in >> your tree, and I think I might have missed a followup patch from you? It >> seems to solve a real problem with in-kernel faults during the dump_mem >> in general, even beyond just an alignment fault. > > I was waiting for someone to say "I saw a problem and it works"... > Would be nice to have a Tested-by tag against it... I've poked at the patch, made one against Fedora, and asked someone in my team to do a scratch build and test on our local highbank/other systems. We'll come back with that tag for ya asap, thanks! Jon.
On 10/23/2012 11:58 AM, Russell King - ARM Linux wrote: > On Tue, Oct 23, 2012 at 12:30:14PM -0400, Jon Masters wrote: >> On 10/05/2012 06:51 AM, Russell King - ARM Linux wrote: >> >> <snip switch out the might_fault __get_user for atomic >> probe_kernel_address related discussion> >> >>> Okay, this should fix the issue... I've only compile tested it so far. >>> Rob, as you have a way to trigger this easily, can you give this patch >>> a go and let me know if it solves your problem? Thanks. >> >> Russell, can you let me know the status of this patch? I don't see it in >> your tree, and I think I might have missed a followup patch from you? It >> seems to solve a real problem with in-kernel faults during the dump_mem >> in general, even beyond just an alignment fault. > > I was waiting for someone to say "I saw a problem and it works"... > Would be nice to have a Tested-by tag against it... I thought I had said it does work and fixes the problem. Anyway, Tested-by: Rob Herring <rob.herring@calxeda.com> Rob
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c index b0179b8..62f429e 100644 --- a/arch/arm/kernel/traps.c +++ b/arch/arm/kernel/traps.c @@ -89,17 +89,8 @@ static void dump_mem(const char *lvl, const char *str, unsigned long bottom, unsigned long top) { unsigned long first; - mm_segment_t fs; int i; - /* - * We need to switch to kernel mode so that we can use __get_user - * to safely read from kernel space. Note that we now dump the - * code first, just in case the backtrace kills us. - */ - fs = get_fs(); - set_fs(KERNEL_DS); - printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top); for (first = bottom & ~31; first < top; first += 32) { @@ -112,7 +103,7 @@ static void dump_mem(const char *lvl, const char *str, unsigned long bottom, for (p = first, i = 0; i < 8 && p < top; i++, p += 4) { if (p >= bottom && p < top) { unsigned long val; - if (__get_user(val, (unsigned long *)p) == 0) + if (probe_kernel_address(p, val) == 0) sprintf(str + i * 9, " %08lx", val); else sprintf(str + i * 9, " ????????"); @@ -120,8 +111,6 @@ static void dump_mem(const char *lvl, const char *str, unsigned long bottom, } printk("%s%04lx:%s\n", lvl, first & 0xffff, str); } - - set_fs(fs); } static void dump_instr(const char *lvl, struct pt_regs *regs) @@ -129,25 +118,18 @@ static void dump_instr(const char *lvl, struct pt_regs *regs) unsigned long addr = instruction_pointer(regs); const int thumb = thumb_mode(regs); const int width = thumb ? 4 : 8; - mm_segment_t fs; char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str; int i; - /* - * We need to switch to kernel mode so that we can use __get_user - * to safely read from kernel space. Note that we now dump the - * code first, just in case the backtrace kills us. - */ - fs = get_fs(); - set_fs(KERNEL_DS); - for (i = -4; i < 1 + !!thumb; i++) { unsigned int val, bad; - if (thumb) - bad = __get_user(val, &((u16 *)addr)[i]); - else - bad = __get_user(val, &((u32 *)addr)[i]); + if (thumb) { + u16 instr; + bad = probe_kernel_address(addr, instr); + val = instr; + } else + bad = probe_kernel_address(addr, val); if (!bad) p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ", @@ -158,8 +140,6 @@ static void dump_instr(const char *lvl, struct pt_regs *regs) } } printk("%sCode: %s\n", lvl, str); - - set_fs(fs); } #ifdef CONFIG_ARM_UNWIND diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c index b9f60eb..f8f14fc 100644 --- a/arch/arm/mm/alignment.c +++ b/arch/arm/mm/alignment.c @@ -749,7 +749,6 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) unsigned long instr = 0, instrptr; int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs); unsigned int type; - mm_segment_t fs; unsigned int fault; u16 tinstr = 0; int isize = 4; @@ -760,16 +759,15 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) instrptr = instruction_pointer(regs); - fs = get_fs(); - set_fs(KERNEL_DS); if (thumb_mode(regs)) { - fault = __get_user(tinstr, (u16 *)(instrptr & ~1)); + unsigned long ptr = instrptr; + fault = probe_kernel_address(ptr, tinstr); if (!fault) { if (cpu_architecture() >= CPU_ARCH_ARMv7 && IS_T32(tinstr)) { /* Thumb-2 32-bit */ u16 tinst2 = 0; - fault = __get_user(tinst2, (u16 *)(instrptr+2)); + fault = probe_kernel_address(ptr + 2, tinst2); instr = (tinstr << 16) | tinst2; thumb2_32b = 1; } else { @@ -778,8 +776,7 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) } } } else - fault = __get_user(instr, (u32 *)instrptr); - set_fs(fs); + fault = probe_kernel_address(instrptr, instr); if (fault) { type = TYPE_FAULT;