The following commit has been merged into the x86/alternatives branch of tip: Commit-ID: ae755b5a45482b5de4d96d6f35823076af77445e Gitweb: https://git.kernel.org/tip/ae755b5a45482b5de4d96d6f35823076af77445e Author: Juergen Gross <jgross@xxxxxxxx> AuthorDate: Thu, 11 Mar 2021 15:23:16 +01:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Thu, 11 Mar 2021 19:58:54 +01:00 x86/paravirt: Switch iret pvops to ALTERNATIVE The iret paravirt op is rather special as it is using a jmp instead of a call instruction. Switch it to ALTERNATIVE. Signed-off-by: Juergen Gross <jgross@xxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20210311142319.4723-12-jgross@xxxxxxxx --- arch/x86/include/asm/paravirt.h | 6 +++--- arch/x86/include/asm/paravirt_types.h | 5 +---- arch/x86/kernel/asm-offsets.c | 5 +----- arch/x86/kernel/paravirt.c | 26 ++------------------------ arch/x86/xen/enlighten_pv.c | 3 +-- 5 files changed, 7 insertions(+), 38 deletions(-) diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index a780509..913acf7 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -747,9 +747,9 @@ extern void default_banner(void); #define PARA_INDIRECT(addr) *addr(%rip) #define INTERRUPT_RETURN \ - PARA_SITE(PARA_PATCH(PV_CPU_iret), \ - ANNOTATE_RETPOLINE_SAFE; \ - jmp PARA_INDIRECT(pv_ops+PV_CPU_iret);) + ANNOTATE_RETPOLINE_SAFE; \ + ALTERNATIVE_TERNARY("jmp *paravirt_iret(%rip);", \ + X86_FEATURE_XENPV, "jmp xen_iret;", "jmp native_iret;") #ifdef CONFIG_DEBUG_ENTRY #define SAVE_FLAGS(clobbers) \ diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h index 45bd216..0afdac8 100644 --- a/arch/x86/include/asm/paravirt_types.h +++ b/arch/x86/include/asm/paravirt_types.h @@ -151,10 +151,6 @@ struct pv_cpu_ops { u64 (*read_pmc)(int counter); - /* Normal iret. Jump to this with the standard iret stack - frame set up. */ - void (*iret)(void); - void (*start_context_switch)(struct task_struct *prev); void (*end_context_switch)(struct task_struct *next); #endif @@ -294,6 +290,7 @@ struct paravirt_patch_template { extern struct pv_info pv_info; extern struct paravirt_patch_template pv_ops; +extern void (*paravirt_iret)(void); #define PARAVIRT_PATCH(x) \ (offsetof(struct paravirt_patch_template, x) / sizeof(void *)) diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index 7365080..ecd3fd6 100644 --- a/arch/x86/kernel/asm-offsets.c +++ b/arch/x86/kernel/asm-offsets.c @@ -61,11 +61,6 @@ static void __used common(void) OFFSET(IA32_RT_SIGFRAME_sigcontext, rt_sigframe_ia32, uc.uc_mcontext); #endif -#ifdef CONFIG_PARAVIRT_XXL - BLANK(); - OFFSET(PV_CPU_iret, paravirt_patch_template, cpu.iret); -#endif - #ifdef CONFIG_XEN BLANK(); OFFSET(XEN_vcpu_info_mask, vcpu_info, evtchn_upcall_mask); diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index a688edf..9b0f568 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -86,25 +86,6 @@ u64 notrace _paravirt_ident_64(u64 x) { return x; } - -static unsigned paravirt_patch_jmp(void *insn_buff, const void *target, - unsigned long addr, unsigned len) -{ - struct branch *b = insn_buff; - unsigned long delta = (unsigned long)target - (addr+5); - - if (len < 5) { -#ifdef CONFIG_RETPOLINE - WARN_ONCE(1, "Failing to patch indirect JMP in %ps\n", (void *)addr); -#endif - return len; /* call too long for patch site */ - } - - b->opcode = 0xe9; /* jmp */ - b->delta = delta; - - return 5; -} #endif DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key); @@ -136,9 +117,6 @@ unsigned paravirt_patch_default(u8 type, void *insn_buff, else if (opfunc == _paravirt_ident_64) ret = paravirt_patch_ident_64(insn_buff, len); - else if (type == PARAVIRT_PATCH(cpu.iret)) - /* If operation requires a jmp, then jmp */ - ret = paravirt_patch_jmp(insn_buff, opfunc, addr, len); #endif else /* Otherwise call the function. */ @@ -313,8 +291,6 @@ struct paravirt_patch_template pv_ops = { .cpu.load_sp0 = native_load_sp0, - .cpu.iret = native_iret, - #ifdef CONFIG_X86_IOPL_IOPERM .cpu.invalidate_io_bitmap = native_tss_invalidate_io_bitmap, .cpu.update_io_bitmap = native_tss_update_io_bitmap, @@ -419,6 +395,8 @@ struct paravirt_patch_template pv_ops = { NOKPROBE_SYMBOL(native_get_debugreg); NOKPROBE_SYMBOL(native_set_debugreg); NOKPROBE_SYMBOL(native_load_idt); + +void (*paravirt_iret)(void) = native_iret; #endif EXPORT_SYMBOL(pv_ops); diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index dc0a337..08dca7b 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -1070,8 +1070,6 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = { .read_pmc = xen_read_pmc, - .iret = xen_iret, - .load_tr_desc = paravirt_nop, .set_ldt = xen_set_ldt, .load_gdt = xen_load_gdt, @@ -1235,6 +1233,7 @@ asmlinkage __visible void __init xen_start_kernel(void) pv_info = xen_info; pv_ops.init.patch = paravirt_patch_default; pv_ops.cpu = xen_cpu_ops; + paravirt_iret = xen_iret; xen_init_irq_ops(); /*
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