x86/io: Define readq()/writeq() to use 64-bit type
PATCH v3 1/1 x86/io: Define readq()/writeq() to use 64-bit type
Since non atomic readq() and writeq() were added some of the drivers would like to use it in a manner of:
#include <io-64-nonatomic-lo-hi.h>
...
pr_debug("Debug value of some register: %016llx\n", readq(addr));
However, lo_hi_readq() always returns __u64 data, while readq() on x86_64 defines it as unsigned long. and thus compiler warns about type mismatch, although they are both 64-bit on x86_64.
Convert readq() and writeq() on x86 to operate on deterministic 64-bit type. The most of architectures in the kernel already are using either unsigned long long, or u64 type for readq() / writeq(). This change propagates consistency in that sense.
While this is not an issue per se, though if someone wants to address it, the anchor could be the commit
797a796a13df ("asm-generic: architecture independent readq/writeq for 32bit environment")
where non-atomic variants had been introduced.
Note, there are only few users of above pattern and they will not be affected because they do cast returned value. The actual warning has been issued on not-yet-upstreamed code.
Potentially we might get a new warnings if some 64-bit only code assigns returned value to unsigned long type of variable. This is assumed to be addressed on case-by-case basis.
---
- convert to u64 instead of unsigned long long
arch/x86/include/asm/io.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
arch/x86/include/asm/io.h +4 -4
@@ -94,10 +94,10 @@ build_mmio_write(__writel, "l", unsigned int, "r", )#ifdef CONFIG_X86_64 -build_mmio_read(readq, "q", unsigned long, "=r", :"memory") -build_mmio_read(__readq, "q", unsigned long, "=r", ) -build_mmio_write(writeq, "q", unsigned long, "r", :"memory") -build_mmio_write(__writeq, "q", unsigned long, "r", ) +build_mmio_read(readq, "q", u64, "=r", :"memory") +build_mmio_read(__readq, "q", u64, "=r", ) +build_mmio_write(writeq, "q", u64, "r", :"memory") +build_mmio_write(__writeq, "q", u64, "r", ) #define readq_relaxed(a) __readq(a) #define writeq_relaxed(v, a) __writeq(v, a)
Signature · 1 line
2.17.0
tip-bot for Andy Shevchenko
merge botx86/io: Define readq()/writeq() to use 64-bit type
Commit-ID: 6469a0ee0a06b2ea1f5afbb1d5a3feed017d4c7a Gitweb: https://git.kernel.org/tip/6469a0ee0a06b2ea1f5afbb1d5a3feed017d4c7a Author: Andy Shevchenko <[email protected]> AuthorDate: Tue, 15 May 2018 14:52:11 +0300 Committer: Ingo Molnar <[email protected]> CommitDate: Fri, 18 May 2018 09:11:26 +0200
x86/io: Define readq()/writeq() to use 64-bit type
Since non atomic readq() and writeq() were added some of the drivers would like to use it in a manner of:
#include <io-64-nonatomic-lo-hi.h>
...
pr_debug("Debug value of some register: %016llx\n", readq(addr));
However, lo_hi_readq() always returns __u64 data, while readq() on x86_64 defines it as unsigned long. and thus compiler warns about type mismatch, although they are both 64-bit on x86_64.
Convert readq() and writeq() on x86 to operate on deterministic 64-bit type. The most of architectures in the kernel already are using either unsigned long long, or u64 type for readq() / writeq(). This change propagates consistency in that sense.
While this is not an issue per se, though if someone wants to address it, the anchor could be the commit:
797a796a13df ("asm-generic: architecture independent readq/writeq for 32bit environment")
where non-atomic variants had been introduced.
Note, there are only few users of above pattern and they will not be affected because they do cast returned value. The actual warning has been issued on not-yet-upstreamed code.
Potentially we might get a new warnings if some 64-bit only code assigns returned value to unsigned long type of variable. This is assumed to be addressed on case-by-case basis.
--- arch/x86/include/asm/io.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
arch/x86/include/asm/io.h +4 -4
@@ -94,10 +94,10 @@ build_mmio_write(__writel, "l", unsigned int, "r", )#ifdef CONFIG_X86_64 -build_mmio_read(readq, "q", unsigned long, "=r", :"memory") -build_mmio_read(__readq, "q", unsigned long, "=r", ) -build_mmio_write(writeq, "q", unsigned long, "r", :"memory") -build_mmio_write(__writeq, "q", unsigned long, "r", ) +build_mmio_read(readq, "q", u64, "=r", :"memory") +build_mmio_read(__readq, "q", u64, "=r", ) +build_mmio_write(writeq, "q", u64, "r", :"memory") +build_mmio_write(__writeq, "q", u64, "r", ) #define readq_relaxed(a) __readq(a) #define writeq_relaxed(v, a) __writeq(v, a)