The patch titled
Subject: squashfs: fix percpu address space issues in decompressor_multi_percpu.c
has been added to the -mm mm-nonmm-unstable branch. Its filename is
squashfs-fix-percpu-address-space-issues-in-decompressor_multi_percpuc.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/squashfs-fix-percpu-address-space-issues-in-decompressor_multi_percpuc.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Uros Bizjak <ubizjak@xxxxxxxxx>
Subject: squashfs: fix percpu address space issues in decompressor_multi_percpu.c
Date: Fri, 30 Aug 2024 11:10:50 +0200
When strict percpu address space checks are enabled, then current direct
casts between the percpu address space and the generic address space fail
the compilation on x86_64 with:
decompressor_multi_percpu.c: In function `squashfs_decompressor_create':
decompressor_multi_percpu.c:49:16: error: cast to generic address space pointer from disjoint `__seg_gs' address space pointer
decompressor_multi_percpu.c: In function `squashfs_decompressor_destroy':
decompressor_multi_percpu.c:64:25: error: cast to `__seg_gs' address space pointer from disjoint generic address space pointer
decompressor_multi_percpu.c: In function `squashfs_decompress':
decompressor_multi_percpu.c:82:25: error: cast to `__seg_gs' address space pointer from disjoint generic address space pointer
Add intermediate casts to unsigned long, as advised in [1] and [2].
Side note: sparse still requires __force when casting from the percpu
address space, although the documentation [2] allows casts to unsigned
long without __force attribute.
Found by GCC's named address space checks.
There were no changes in the resulting object file.
[1] https://gcc.gnu.org/onlinedocs/gcc/Named-Address-Spaces.html#x86-Named-Address-Spaces
[2] https://sparse.docs.kernel.org/en/latest/annotations.html#address-space-name
Link: https://lkml.kernel.org/r/20240830091104.13049-1-ubizjak@xxxxxxxxx
Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx>
Cc: Phillip Lougher <phillip@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/squashfs/decompressor_multi_percpu.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/fs/squashfs/decompressor_multi_percpu.c~squashfs-fix-percpu-address-space-issues-in-decompressor_multi_percpuc
+++ a/fs/squashfs/decompressor_multi_percpu.c
@@ -46,7 +46,7 @@ static void *squashfs_decompressor_creat
}
kfree(comp_opts);
- return (__force void *) percpu;
+ return (void *)(__force unsigned long) percpu;
out:
for_each_possible_cpu(cpu) {
@@ -61,7 +61,7 @@ out:
static void squashfs_decompressor_destroy(struct squashfs_sb_info *msblk)
{
struct squashfs_stream __percpu *percpu =
- (struct squashfs_stream __percpu *) msblk->stream;
+ (void __percpu *)(unsigned long) msblk->stream;
struct squashfs_stream *stream;
int cpu;
@@ -79,7 +79,7 @@ static int squashfs_decompress(struct sq
{
struct squashfs_stream *stream;
struct squashfs_stream __percpu *percpu =
- (struct squashfs_stream __percpu *) msblk->stream;
+ (void __percpu *)(unsigned long) msblk->stream;
int res;
local_lock(&percpu->lock);
_
Patches currently in -mm which might be from ubizjak@xxxxxxxxx are
mm-z3fold-add-__percpu-annotation-to-unbuddied-pointer-in-struct-z3fold_pool.patch
errh-add-err_ptr_pcpu-ptr_err_pcpu-and-is_err_pcpu-macros.patch
mm-kmemleak-use-is_err_pcpu-for-pointer-in-the-percpu-address-space.patch
kexec-use-atomic_try_cmpxchg_acquire-in-kexec_trylock.patch
lib-percpu_counter-add-missing-__percpu-qualifier-to-a-cast.patch
squashfs-fix-percpu-address-space-issues-in-decompressor_multi_percpuc.patch
