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| author | Uros Bizjak <ubizjak@gmail.com> | 2023-12-13 16:03:15 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2024-01-09 09:39:15 +0100 |
| commit | de8c6a352131f642b82474abe0cbb5dd26a7e081 (patch) | |
| tree | 9445efbc545555ee20a61e35fdf73264519f6791 /arch/x86 | |
| parent | 86ed430cf5296ca97a66f1f37e30b7dfe47cd36f (diff) | |
| download | lwn-de8c6a352131f642b82474abe0cbb5dd26a7e081.tar.gz lwn-de8c6a352131f642b82474abe0cbb5dd26a7e081.zip | |
x86/percpu: Use %RIP-relative address in untagged_addr()
%RIP-relative addresses are nowadays correctly handled in alternative
instructions, so remove misleading comment and improve assembly to
use %RIP-relative address.
Also, explicitly using %gs: prefix will segfault for non-SMP builds.
Use macros from percpu.h which will DTRT with segment prefix register
as far as SMP/non-SMP builds are concerned.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradaed.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/all/20231213150357.5942-1-ubizjak%40gmail.com
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/uaccess_64.h | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h index f2c02e4469cc..01455c0b070c 100644 --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -11,6 +11,7 @@ #include <asm/alternative.h> #include <asm/cpufeatures.h> #include <asm/page.h> +#include <asm/percpu.h> #ifdef CONFIG_ADDRESS_MASKING /* @@ -18,14 +19,10 @@ */ static inline unsigned long __untagged_addr(unsigned long addr) { - /* - * Refer tlbstate_untag_mask directly to avoid RIP-relative relocation - * in alternative instructions. The relocation gets wrong when gets - * copied to the target place. - */ asm (ALTERNATIVE("", - "and %%gs:tlbstate_untag_mask, %[addr]\n\t", X86_FEATURE_LAM) - : [addr] "+r" (addr) : "m" (tlbstate_untag_mask)); + "and " __percpu_arg([mask]) ", %[addr]", X86_FEATURE_LAM) + : [addr] "+r" (addr) + : [mask] "m" (__my_cpu_var(tlbstate_untag_mask))); return addr; } |