On March 6, 2025 1:33:43 PM PST, tip-bot2 for Uros Bizjak <tip-bot2@xxxxxxxxxxxxx> wrote: >The following commit has been merged into the x86/asm branch of tip: > >Commit-ID: aa3942d4d12ef57f031faa2772fe410c24191e36 >Gitweb: https://git.kernel.org/tip/aa3942d4d12ef57f031faa2772fe410c24191e36 >Author: Uros Bizjak <ubizjak@xxxxxxxxx> >AuthorDate: Thu, 06 Mar 2025 15:52:11 +01:00 >Committer: Ingo Molnar <mingo@xxxxxxxxxx> >CommitterDate: Thu, 06 Mar 2025 22:04:48 +01:00 > >x86/kexec: Merge x86_32 and x86_64 code using macros from <asm/asm.h> > >Merge common x86_32 and x86_64 code in crash_setup_regs() >using macros from <asm/asm.h>. > >The compiled object files before and after the patch are unchanged. > >Signed-off-by: Uros Bizjak <ubizjak@xxxxxxxxx> >Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> >Cc: David Woodhouse <dwmw@xxxxxxxxxxxx> >Cc: Baoquan He <bhe@xxxxxxxxxx> >Cc: Vivek Goyal <vgoyal@xxxxxxxxxx> >Cc: Dave Young <dyoung@xxxxxxxxxx> >Cc: Ard Biesheuvel <ardb@xxxxxxxxxx> >Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> >Link: https://lore.kernel.org/r/20250306145227.55819-1-ubizjak@xxxxxxxxx >--- > arch/x86/include/asm/kexec.h | 58 +++++++++++++++-------------------- > 1 file changed, 25 insertions(+), 33 deletions(-) > >diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h >index 8ad1874..e3589d6 100644 >--- a/arch/x86/include/asm/kexec.h >+++ b/arch/x86/include/asm/kexec.h >@@ -18,6 +18,7 @@ > #include <linux/string.h> > #include <linux/kernel.h> > >+#include <asm/asm.h> > #include <asm/page.h> > #include <asm/ptrace.h> > >@@ -71,41 +72,32 @@ static inline void crash_setup_regs(struct pt_regs *newregs, > if (oldregs) { > memcpy(newregs, oldregs, sizeof(*newregs)); > } else { >+ asm volatile("mov %%" _ASM_BX ",%0" : "=m"(newregs->bx)); >+ asm volatile("mov %%" _ASM_CX ",%0" : "=m"(newregs->cx)); >+ asm volatile("mov %%" _ASM_DX ",%0" : "=m"(newregs->dx)); >+ asm volatile("mov %%" _ASM_SI ",%0" : "=m"(newregs->si)); >+ asm volatile("mov %%" _ASM_DI ",%0" : "=m"(newregs->di)); >+ asm volatile("mov %%" _ASM_BP ",%0" : "=m"(newregs->bp)); >+ asm volatile("mov %%" _ASM_AX ",%0" : "=m"(newregs->ax)); >+ asm volatile("mov %%" _ASM_SP ",%0" : "=m"(newregs->sp)); >+#ifdef CONFIG_X86_64 >+ asm volatile("mov %%r8,%0" : "=m"(newregs->r8)); >+ asm volatile("mov %%r9,%0" : "=m"(newregs->r9)); >+ asm volatile("mov %%r10,%0" : "=m"(newregs->r10)); >+ asm volatile("mov %%r11,%0" : "=m"(newregs->r11)); >+ asm volatile("mov %%r12,%0" : "=m"(newregs->r12)); >+ asm volatile("mov %%r13,%0" : "=m"(newregs->r13)); >+ asm volatile("mov %%r14,%0" : "=m"(newregs->r14)); >+ asm volatile("mov %%r15,%0" : "=m"(newregs->r15)); >+#endif >+ asm volatile("mov %%ss,%k0" : "=a"(newregs->ss)); >+ asm volatile("mov %%cs,%k0" : "=a"(newregs->cs)); > #ifdef CONFIG_X86_32 >- asm volatile("movl %%ebx,%0" : "=m"(newregs->bx)); >- asm volatile("movl %%ecx,%0" : "=m"(newregs->cx)); >- asm volatile("movl %%edx,%0" : "=m"(newregs->dx)); >- asm volatile("movl %%esi,%0" : "=m"(newregs->si)); >- asm volatile("movl %%edi,%0" : "=m"(newregs->di)); >- asm volatile("movl %%ebp,%0" : "=m"(newregs->bp)); >- asm volatile("movl %%eax,%0" : "=m"(newregs->ax)); >- asm volatile("movl %%esp,%0" : "=m"(newregs->sp)); >- asm volatile("movl %%ss, %%eax;" :"=a"(newregs->ss)); >- asm volatile("movl %%cs, %%eax;" :"=a"(newregs->cs)); >- asm volatile("movl %%ds, %%eax;" :"=a"(newregs->ds)); >- asm volatile("movl %%es, %%eax;" :"=a"(newregs->es)); >- asm volatile("pushfl; popl %0" :"=m"(newregs->flags)); >-#else >- asm volatile("movq %%rbx,%0" : "=m"(newregs->bx)); >- asm volatile("movq %%rcx,%0" : "=m"(newregs->cx)); >- asm volatile("movq %%rdx,%0" : "=m"(newregs->dx)); >- asm volatile("movq %%rsi,%0" : "=m"(newregs->si)); >- asm volatile("movq %%rdi,%0" : "=m"(newregs->di)); >- asm volatile("movq %%rbp,%0" : "=m"(newregs->bp)); >- asm volatile("movq %%rax,%0" : "=m"(newregs->ax)); >- asm volatile("movq %%rsp,%0" : "=m"(newregs->sp)); >- asm volatile("movq %%r8,%0" : "=m"(newregs->r8)); >- asm volatile("movq %%r9,%0" : "=m"(newregs->r9)); >- asm volatile("movq %%r10,%0" : "=m"(newregs->r10)); >- asm volatile("movq %%r11,%0" : "=m"(newregs->r11)); >- asm volatile("movq %%r12,%0" : "=m"(newregs->r12)); >- asm volatile("movq %%r13,%0" : "=m"(newregs->r13)); >- asm volatile("movq %%r14,%0" : "=m"(newregs->r14)); >- asm volatile("movq %%r15,%0" : "=m"(newregs->r15)); >- asm volatile("movl %%ss, %%eax;" :"=a"(newregs->ss)); >- asm volatile("movl %%cs, %%eax;" :"=a"(newregs->cs)); >- asm volatile("pushfq; popq %0" :"=m"(newregs->flags)); >+ asm volatile("mov %%ds,%k0" : "=a"(newregs->ds)); >+ asm volatile("mov %%es,%k0" : "=a"(newregs->es)); > #endif >+ asm volatile("pushf\n\t" >+ "pop %0" : "=m"(newregs->flags)); > newregs->ip = _THIS_IP_; > } > } Incidentally, doing this in C code is obviously completely broken, especially doing it in multiple statements. You have no idea what the compiler has messed with before you get there.
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