From: <gregkh@linuxfoundation.org>
To: vgupta@synopsys.com, stable@vger.kernel.org
Cc: <stable@vger.kernel.org>
Subject: FAILED: patch "[PATCH] ARC: mm: fix build breakage with STRICT_MM_TYPECHECKS" failed to apply to 4.4-stable tree
Date: Mon, 05 Sep 2016 15:06:01 +0200 [thread overview]
Message-ID: <1473080761121157@kroah.com> (raw)
The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 1c3c909303924d30145601f47b6c058fdd2cbc2e Mon Sep 17 00:00:00 2001
From: Vineet Gupta <vgupta@synopsys.com>
Date: Tue, 16 Aug 2016 18:27:07 -0700
Subject: [PATCH] ARC: mm: fix build breakage with STRICT_MM_TYPECHECKS
MIME-Version: 1.0
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| CC mm/memory.o
| In file included from ../mm/memory.c:53:0:
| ../include/linux/pfn_t.h: In function ‘pfn_t_pte’:
| ../include/linux/pfn_t.h:78:2: error: conversion to non-scalar type requested
| return pfn_pte(pfn_t_to_pfn(pfn), pgprot);
With STRICT_MM_TYPECHECKS pte_t is a struct and the offending code
forces a cast which ends up shifting a struct and hence the gcc warning.
Note that in recent past some of the arches (aarch64, s390) made
STRICT_MM_TYPECHECKS default, but we don't for ARC as this leads to slightly
worse generated code, given ARC ABI definition of returning structs
(which pte_t would become)
Quoting from ARC ABI...
"Results of type struct are returned in a caller-supplied temporary
variable whose address is passed in r0.
For such functions, the arguments are shifted so that they are
passed in r1 and up."
So
- struct to be returned would be allocated on stack requiring extra
code at call sites
- callee updates stack memory to facilitate the return (vs. simple
MOV into return reg r0)
Hence STRICT_MM_TYPECHECKS is not enabled by default for ARC
Cc: <stable@vger.kernel.org> #4.4+
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/include/asm/pgtable.h b/arch/arc/include/asm/pgtable.h
index 0f92d97432a2..89eeb3720051 100644
--- a/arch/arc/include/asm/pgtable.h
+++ b/arch/arc/include/asm/pgtable.h
@@ -280,7 +280,7 @@ static inline void pmd_set(pmd_t *pmdp, pte_t *ptep)
#define pte_page(pte) pfn_to_page(pte_pfn(pte))
#define mk_pte(page, prot) pfn_pte(page_to_pfn(page), prot)
-#define pfn_pte(pfn, prot) (__pte(((pte_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)))
+#define pfn_pte(pfn, prot) __pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot))
/* Don't use virt_to_pfn for macros below: could cause truncations for PAE40*/
#define pte_pfn(pte) (pte_val(pte) >> PAGE_SHIFT)
next reply other threads:[~2016-09-05 13:06 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-05 13:06 gregkh [this message]
2016-09-06 17:24 ` FAILED: patch "[PATCH] ARC: mm: fix build breakage with STRICT_MM_TYPECHECKS" failed to apply to 4.4-stable tree Vineet Gupta
2016-09-09 14:19 ` gregkh
2016-09-09 16:47 ` Vineet Gupta
2016-09-10 15:50 ` gregkh
2016-09-12 16:32 ` [PATCH] ARC: mm: fix build breakage with STRICT_MM_TYPECHECKS Vineet Gupta
2016-09-12 17:08 ` gregkh @ linuxfoundation . org
2016-09-12 17:39 ` Vineet Gupta
2016-09-12 18:04 ` Vineet Gupta
2016-09-13 6:12 ` gregkh
2016-09-13 16:29 ` Vineet Gupta
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