Re: rfc: remove print_vma_addr ? (was Re: [PATCH 00/16] remove eight obsolete architectures)

[Matthew Wilcox]

On Thu, Mar 15, 2018 at 09:56:46AM -0700, Joe Perches wrote:
> I have a patchset that creates a vsprintf extension for
> print_vma_addr and removes all the uses similar to the
> print_symbol() removal.
> 
> This now avoids any possible printk interleaving.
> 
> Unfortunately, without some #ifdef in vsprintf, which
> I would like to avoid, it increases the nommu kernel
> size by ~500 bytes.
> 
> Anyone think this is acceptable?
> 
> Here's the overall patch, but I have it as a series
> ---
>  Documentation/core-api/printk-formats.rst |  9 +
>  arch/arm64/kernel/traps.c | 13 +++
>  arch/mips/mm/fault.c  | 16 -
>  arch/parisc/mm/fault.c| 15 
>  arch/riscv/kernel/traps.c | 11 +++---
>  arch/s390/mm/fault.c  |  7 ++--
>  arch/sparc/mm/fault_32.c  |  8 ++---
>  arch/sparc/mm/fault_64.c  |  8 ++---
>  arch/tile/kernel/signal.c |  9 ++---
>  arch/um/kernel/trap.c | 13 +++
>  arch/x86/kernel/signal.c  | 10 ++
>  arch/x86/kernel/traps.c   | 18 --
>  arch/x86/mm/fault.c   | 12 +++
>  include/linux/mm.h|  1 -
>  lib/vsprintf.c| 58 
> ++-
>  mm/memory.c   | 33 --
>  16 files changed, 112 insertions(+), 129 deletions(-)

This doesn't feel like a huge win since it's only called ~once per
architecture.  I'd be more excited if it made the printing of the whole
thing standardised; eg we have a print_fault() function in mm/memory.c
which takes a suitable set of arguments.
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Re: rfc: remove print_vma_addr ? (was Re: [PATCH 00/16] remove eight obsolete architectures)

[Joe Perches]

On Thu, 2018-03-15 at 10:08 -0700, Matthew Wilcox wrote:
> On Thu, Mar 15, 2018 at 09:56:46AM -0700, Joe Perches wrote:
> > I have a patchset that creates a vsprintf extension for
> > print_vma_addr and removes all the uses similar to the
> > print_symbol() removal.
> > 
> > This now avoids any possible printk interleaving.
> > 
> > Unfortunately, without some #ifdef in vsprintf, which
> > I would like to avoid, it increases the nommu kernel
> > size by ~500 bytes.
> > 
> > Anyone think this is acceptable?
[]
> This doesn't feel like a huge win since it's only called ~once per
> architecture.  I'd be more excited if it made the printing of the whole
> thing standardised; eg we have a print_fault() function in mm/memory.c
> which takes a suitable set of arguments.

Sure but perhaps that's not feasible as the surrounding output
is per-arch specific.

What could be a standardized fault message here?

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rfc: remove print_vma_addr ? (was Re: [PATCH 00/16] remove eight obsolete architectures)

[Joe Perches]

On Thu, 2018-03-15 at 10:48 +0100, Geert Uytterhoeven wrote:
> Hi David,
> 
> On Thu, Mar 15, 2018 at 10:42 AM, David Howells  wrote:
> > Do we have anything left that still implements NOMMU?
> 
> Sure: arm, c6x, m68k, microblaze, and  sh.

I have a patchset that creates a vsprintf extension for
print_vma_addr and removes all the uses similar to the
print_symbol() removal.

This now avoids any possible printk interleaving.

Unfortunately, without some #ifdef in vsprintf, which
I would like to avoid, it increases the nommu kernel
size by ~500 bytes.

Anyone think this is acceptable?

Here's the overall patch, but I have it as a series
---
 Documentation/core-api/printk-formats.rst |  9 +
 arch/arm64/kernel/traps.c | 13 +++
 arch/mips/mm/fault.c  | 16 -
 arch/parisc/mm/fault.c| 15 
 arch/riscv/kernel/traps.c | 11 +++---
 arch/s390/mm/fault.c  |  7 ++--
 arch/sparc/mm/fault_32.c  |  8 ++---
 arch/sparc/mm/fault_64.c  |  8 ++---
 arch/tile/kernel/signal.c |  9 ++---
 arch/um/kernel/trap.c | 13 +++
 arch/x86/kernel/signal.c  | 10 ++
 arch/x86/kernel/traps.c   | 18 --
 arch/x86/mm/fault.c   | 12 +++
 include/linux/mm.h|  1 -
 lib/vsprintf.c| 58 ++-
 mm/memory.c   | 33 --
 16 files changed, 112 insertions(+), 129 deletions(-)

diff --git a/Documentation/core-api/printk-formats.rst 
b/Documentation/core-api/printk-formats.rst
index 934559b3c130..10a91da1bc83 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -157,6 +157,15 @@ DMA address types dma_addr_t
 For printing a dma_addr_t type which can vary based on build options,
 regardless of the width of the CPU data path.
 
+VMA name and address
+
+
+::
+
+   %pav[hexstart+hexsize] or ?[0+0] if unavailable
+
+For any address, print the vma's name and its starting address and size
+
 Passed by reference.
 
 Raw buffer as an escaped string
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 2b478565d774..48edf812ce8b 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -242,13 +242,14 @@ void arm64_force_sig_info(struct siginfo *info, const 
char *str,
if (!show_unhandled_signals_ratelimited())
goto send_sig;
 
-   pr_info("%s[%d]: unhandled exception: ", tsk->comm, task_pid_nr(tsk));
if (esr)
-   pr_cont("%s, ESR 0x%08x, ", esr_get_class_string(esr), esr);
-
-   pr_cont("%s", str);
-   print_vma_addr(KERN_CONT " in ", regs->pc);
-   pr_cont("\n");
+   pr_info("%s[%d]: unhandled exception: %s, ESR 0x%08x, %s in 
%pav\n",
+   tsk->comm, task_pid_nr(tsk),
+   esr_get_class_string(esr), esr,
+   str, >pc);
+   else
+   pr_info("%s[%d]: unhandled exception: %s in %pav\n",
+   tsk->comm, task_pid_nr(tsk), str, >pc);
__show_regs(regs);
 
 send_sig:
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index 4f8f5bf46977..ce7bf077a0f5 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -213,14 +213,14 @@ static void __kprobes __do_page_fault(struct pt_regs 
*regs, unsigned long write,
tsk->comm,
write ? "write access to" : "read access from",
field, address);
-   pr_info("epc = %0*lx in", field,
-   (unsigned long) regs->cp0_epc);
-   print_vma_addr(KERN_CONT " ", regs->cp0_epc);
-   pr_cont("\n");
-   pr_info("ra  = %0*lx in", field,
-   (unsigned long) regs->regs[31]);
-   print_vma_addr(KERN_CONT " ", regs->regs[31]);
-   pr_cont("\n");
+   pr_info("epc = %0*lx in %pav\n",
+   field,
+   (unsigned long)regs->cp0_epc,
+   >cp0_epc);
+   pr_info("ra  = %0*lx in %pav\n",
+   field,
+   (unsigned long)regs->regs[31],
+   >regs[31]);
}
current->thread.trap_nr = (regs->cp0_cause >> 2) & 0x1f;
info.si_signo = SIGSEGV;
diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index e247edbca68e..877cea702714 100644
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -240,17 +240,14 @@ show_signal_msg(struct pt_regs *regs, unsigned long