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From: Greg Ungerer <gerg@linux-m68k.org>
To: Nicolas Pitre <nicolas.pitre@linaro.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	David Howells <dhowells@redhat.com>
Subject: Re: [PATCH v4 00/12] allow BFLT executables on systems with a MMU
Date: Thu, 21 Jul 2016 16:58:12 +1000	[thread overview]
Message-ID: <6d7b45eb-8085-47fa-fc31-5fb26b7dd009@linux-m68k.org> (raw)
In-Reply-To: <1469042561-7360-1-git-send-email-nicolas.pitre@linaro.org>

Hi Nicolas,

On 21/07/16 05:22, Nicolas Pitre wrote:
> This series provides the necessary changes to allow "flat" executable
> binaries meant for no-MMU systems to actually run on systems with a MMU.
> Also thrown in are various cleanups to binfmt_flat.c.

I got to the bottom of why I couldn't run m68k flat binaries on
an MMU enabled m68k system. I had to fix the regs setup, with the
patch below. With this I can now run flat binaries on my ColdFire
MMU enabled system.

This change is completely independent of your patch series so I'll
push this separately via the linux-m68k list and my m68knommu git
tree.

Regards
Greg



Subject: [PATCH] m68k: fix bFLT executable running on MMU enabled systems

Even after recent changes to support running flat format executables on
MMU enabled systems (by nicolas.pitre@linaro.org) they still failed to
run on m68k/ColdFire MMU enabled systems. On trying to run a flat format
binary the application would immediately crash with a SIGSEGV.

Code to setup the D5 register with the base of the application data
region was only in the non-MMU code path, so it was not being set for
the MMU enabled case. Flat binaries on m68k/ColdFire use this to support
GOT/PIC flat built application code.

Fix this so that D5 is always setup when loading/running a bFLT executable
on m68k systems.

Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
---
 arch/m68k/include/asm/flat.h      | 6 ++++++
 arch/m68k/include/asm/processor.h | 2 --
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/m68k/include/asm/flat.h b/arch/m68k/include/asm/flat.h
index f3f592d..a97c479 100644
--- a/arch/m68k/include/asm/flat.h
+++ b/arch/m68k/include/asm/flat.h
@@ -19,4 +19,10 @@ static inline int flat_set_persistent(unsigned long relval,
 	return 0;
 }
 
+#define FLAT_PLAT_INIT(regs) \
+	do { \
+		if (current->mm) \
+			(regs)->d5 = current->mm->start_data; \
+	} while (0)
+
 #endif /* __M68KNOMMU_FLAT_H__ */
diff --git a/arch/m68k/include/asm/processor.h b/arch/m68k/include/asm/processor.h
index a6ce2ec..46672d1 100644
--- a/arch/m68k/include/asm/processor.h
+++ b/arch/m68k/include/asm/processor.h
@@ -131,8 +131,6 @@ extern int handle_kernel_fault(struct pt_regs *regs);
 do {                                                    \
 	(_regs)->pc = (_pc);                            \
 	setframeformat(_regs);                          \
-	if (current->mm)                                \
-		(_regs)->d5 = current->mm->start_data;  \
 	(_regs)->sr &= ~0x2000;                         \
 	wrusp(_usp);                                    \
 } while(0)
-- 
1.9.1



  parent reply	other threads:[~2016-07-21  6:57 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-20 19:22 [PATCH v4 00/12] allow BFLT executables on systems with a MMU Nicolas Pitre
2016-07-20 19:22 ` [PATCH v4 01/12] binfmt_flat: assorted cleanups Nicolas Pitre
2016-07-20 19:22 ` [PATCH v4 02/12] binfmt_flat: convert printk invocations to their modern form Nicolas Pitre
2016-07-20 19:22 ` [PATCH v4 03/12] binfmt_flat: prevent kernel dammage from corrupted executable headers Nicolas Pitre
2016-07-20 19:22 ` [PATCH v4 04/12] elf_fdpic_transfer_args_to_stack(): make it generic Nicolas Pitre
2016-07-20 19:22 ` [PATCH v4 05/12] binfmt_flat: use generic transfer_args_to_stack() Nicolas Pitre
2016-07-20 19:22 ` [PATCH v4 06/12] binfmt_flat: clean up create_flat_tables() and stack accesses Nicolas Pitre
2016-07-20 19:22 ` [PATCH v4 07/12] binfmt_flat: use proper user space accessors with relocs processing code Nicolas Pitre
2016-07-20 19:22 ` [PATCH v4 08/12] binfmt_flat: use proper user space accessors with old relocs code Nicolas Pitre
2016-07-20 19:22 ` [PATCH v4 09/12] binfmt_flat: use clear_user() rather than memset() to clear .bss Nicolas Pitre
2016-07-20 19:22 ` [PATCH v4 10/12] binfmt_flat: update libraries' data segment pointer with userspace accessors Nicolas Pitre
2016-07-20 19:22 ` [PATCH v4 11/12] binfmt_flat: add MMU-specific support Nicolas Pitre
2016-07-20 19:22 ` [PATCH v4 12/12] binfmt_flat: allow compressed flat binary format to work on MMU systems Nicolas Pitre
2016-07-21  6:58 ` Greg Ungerer [this message]
2016-07-21 14:48   ` [PATCH v4 00/12] allow BFLT executables on systems with a MMU Nicolas Pitre
2016-07-22  7:28     ` Greg Ungerer
2016-07-22 15:06       ` One Thousand Gnomes
2016-07-22 19:22       ` Russell King - ARM Linux
2016-07-22 19:45         ` Nicolas Pitre

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