diff options
| author | Andi Kleen <ak@linux.intel.com> | 2017-04-09 22:10:40 -0700 |
|---|---|---|
| committer | Andi Kleen <ak@linux.intel.com> | 2021-04-04 21:52:42 -0700 |
| commit | ed25a7557151e54a28faef509c93acff5732ea23 (patch) | |
| tree | ebb46a7ea6ea03db50fa5e1bdc26608085138e82 | |
| parent | ce689497934d6f14f03502062416d94a199dc411 (diff) | |
| download | linux-misc-ed25a7557151e54a28faef509c93acff5732ea23.tar.gz | |
lto: Use C version for SYSCALL_ALIAS / cond_syscall
With LTO aliases get largely resolved in the compiler, not in the linker.
Implement cond_syscall and SYSCALL_ALIAS in C to let the compiler
understand the aliases so that it can resolve it properly.
Likely the architecture specific versions are now not needed
anymore, but I kept them for now.
There is one sublety here:
The assembler version didn't care whether there was a prototype
or not. This variant assumes there is no prototypes because
it uses a dummy (void) signature. This works for sys_ni.c,
but breaks for kernel/time/posix-stubs.c. To avoid problems
here I added a second variant of the macro (_PROTO) that
uses the previous type.
I actually tried to avoid this by adding prototypes for
sys_ni and only use the _PROTO variant, but it resulted in very large
patches and lots of problems with all the different cases.
Eventually I gave up and just special cases the prototype
case in posix-stubs.c
Signed-off-by: Andi Kleen <ak@linux.intel.com>
| -rw-r--r-- | include/linux/linkage.h | 16 | ||||
| -rw-r--r-- | kernel/time/posix-stubs.c | 2 |
2 files changed, 9 insertions, 9 deletions
diff --git a/include/linux/linkage.h b/include/linux/linkage.h index dbf8506decca0..645e5a73b9edf 100644 --- a/include/linux/linkage.h +++ b/include/linux/linkage.h @@ -23,17 +23,17 @@ #endif #ifndef cond_syscall -#define cond_syscall(x) asm( \ - ".weak " __stringify(x) "\n\t" \ - ".set " __stringify(x) "," \ - __stringify(sys_ni_syscall)) +#define cond_syscall(x) \ + extern long x(void) __attribute__((alias("sys_ni_syscall"), weak)); #endif #ifndef SYSCALL_ALIAS -#define SYSCALL_ALIAS(alias, name) asm( \ - ".globl " __stringify(alias) "\n\t" \ - ".set " __stringify(alias) "," \ - __stringify(name)) +#define SYSCALL_ALIAS(a, name) \ + long a(void) __attribute__((alias(__stringify(name)))) +#define SYSCALL_ALIAS_PROTO(a, name) \ + typeof(a) a __attribute__((alias(__stringify(name)))) +#else +#define SYSCALL_ALIAS_PROTO(a, name) SYSCALL_ALIAS(a, name) #endif #define __page_aligned_data __section(".data..page_aligned") __aligned(PAGE_SIZE) diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c index fcb3b21d8bdcd..24fafe7782a96 100644 --- a/kernel/time/posix-stubs.c +++ b/kernel/time/posix-stubs.c @@ -31,7 +31,7 @@ asmlinkage long sys_ni_posix_timers(void) } #ifndef SYS_NI -#define SYS_NI(name) SYSCALL_ALIAS(sys_##name, sys_ni_posix_timers) +#define SYS_NI(name) SYSCALL_ALIAS_PROTO(sys_##name, sys_ni_posix_timers) #endif #ifndef COMPAT_SYS_NI |