[PATCH] squashfs: Fix percpu address space issues in decompressor_multi_percpu.c
From: Uros Bizjak
Date: Fri Aug 30 2024 - 05:11:42 EST
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
Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx>
Cc: Phillip Lougher <phillip@xxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/squashfs/decompressor_multi_percpu.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/squashfs/decompressor_multi_percpu.c b/fs/squashfs/decompressor_multi_percpu.c
index 8a218e7c2390..e4d7e507b268 100644
--- a/fs/squashfs/decompressor_multi_percpu.c
+++ b/fs/squashfs/decompressor_multi_percpu.c
@@ -46,7 +46,7 @@ static void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
}
kfree(comp_opts);
- return (__force void *) percpu;
+ return (void *)(__force unsigned long) percpu;
out:
for_each_possible_cpu(cpu) {
@@ -61,7 +61,7 @@ static void *squashfs_decompressor_create(struct squashfs_sb_info *msblk,
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 squashfs_sb_info *msblk, struct bio *bio,
{
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);
--
2.46.0