From e05139f2569ecf699b229a6473a86cdffed62956 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Wed, 28 Sep 2011 16:56:51 +0100 Subject: x86-64: Don't apply destructive erratum workaround on unaffected CPUs Erratum 93 applies to AMD K8 CPUs only, and its workaround (forcing the upper 32 bits of %rip to all get set under certain conditions) is actually getting in the way of analyzing page faults occurring during EFI physical mode runtime calls (in particular the page table walk shown is completely unrelated to the actual fault). This is because typically EFI runtime code lives in the space between 2G and 4G, which - modulo the above manipulation - is likely to overlap with the kernel or modules area. While even for the other errata workarounds their taking effect could be limited to just the affected CPUs, none of them appears to be destructive, and they're generally getting called only outside of performance critical paths, so they're being left untouched. Signed-off-by: Jan Beulich Link: http://lkml.kernel.org/r/4E835FE30200007800058464@nat28.tlf.novell.com Signed-off-by: Ingo Molnar --- arch/x86/mm/fault.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 0d17c8c50ac..9c7378df740 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -420,12 +420,14 @@ static noinline __kprobes int vmalloc_fault(unsigned long address) return 0; } +#ifdef CONFIG_CPU_SUP_AMD static const char errata93_warning[] = KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n" "******* Working around it, but it may cause SEGVs or burn power.\n" "******* Please consider a BIOS update.\n" "******* Disabling USB legacy in the BIOS may also help.\n"; +#endif /* * No vm86 mode in 64-bit mode: @@ -505,7 +507,11 @@ bad: */ static int is_errata93(struct pt_regs *regs, unsigned long address) { -#ifdef CONFIG_X86_64 +#if defined(CONFIG_X86_64) && defined(CONFIG_CPU_SUP_AMD) + if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD + || boot_cpu_data.x86 != 0xf) + return 0; + if (address != regs->ip) return 0; -- cgit v1.2.3-18-g5258 From eab9e6137f237681a04649e786cc4d942bedd6d1 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Wed, 28 Sep 2011 16:57:52 +0100 Subject: x86-64: Fix CFI data for interrupt frames The patch titled "x86: Don't use frame pointer to save old stack on irq entry" did not properly adjust CFI directives, so this patch is a follow-up to that one. With the old stack pointer no longer stored in a callee-saved register (plus some offset), we now have to use a CFA expression to describe the memory location where it is being found. This requires the use of .cfi_escape (allowing arbitrary byte streams to be emitted into .eh_frame), as there is no .cfi_def_cfa_expression (which also cannot reasonably be expected, as it would require a full expression parser). Signed-off-by: Jan Beulich Cc: Frederic Weisbecker Link: http://lkml.kernel.org/r/4E8360200200007800058467@nat28.tlf.novell.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/dwarf2.h | 2 ++ arch/x86/kernel/entry_64.S | 14 +++++++++----- 2 files changed, 11 insertions(+), 5 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/include/asm/dwarf2.h b/arch/x86/include/asm/dwarf2.h index 32609919931..f6f15986df6 100644 --- a/arch/x86/include/asm/dwarf2.h +++ b/arch/x86/include/asm/dwarf2.h @@ -27,6 +27,7 @@ #define CFI_REMEMBER_STATE .cfi_remember_state #define CFI_RESTORE_STATE .cfi_restore_state #define CFI_UNDEFINED .cfi_undefined +#define CFI_ESCAPE .cfi_escape #ifdef CONFIG_AS_CFI_SIGNAL_FRAME #define CFI_SIGNAL_FRAME .cfi_signal_frame @@ -68,6 +69,7 @@ #define CFI_REMEMBER_STATE cfi_ignore #define CFI_RESTORE_STATE cfi_ignore #define CFI_UNDEFINED cfi_ignore +#define CFI_ESCAPE cfi_ignore #define CFI_SIGNAL_FRAME cfi_ignore #endif diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 6419bb05ecd..faf8d5e74b0 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -331,10 +331,15 @@ ENDPROC(native_usergs_sysret64) 1: incl PER_CPU_VAR(irq_count) jne 2f mov PER_CPU_VAR(irq_stack_ptr),%rsp - EMPTY_FRAME 0 + CFI_DEF_CFA_REGISTER rsi 2: /* Store previous stack value */ pushq %rsi + CFI_ESCAPE 0x0f /* DW_CFA_def_cfa_expression */, 6, \ + 0x77 /* DW_OP_breg7 */, 0, \ + 0x06 /* DW_OP_deref */, \ + 0x08 /* DW_OP_const1u */, SS+8-RBP, \ + 0x22 /* DW_OP_plus */ /* We entered an interrupt context - irqs are off: */ TRACE_IRQS_OFF .endm @@ -788,7 +793,6 @@ END(interrupt) subq $ORIG_RAX-RBP, %rsp CFI_ADJUST_CFA_OFFSET ORIG_RAX-RBP SAVE_ARGS_IRQ - PARTIAL_FRAME 0 call \func .endm @@ -813,10 +817,10 @@ ret_from_intr: /* Restore saved previous stack */ popq %rsi - leaq 16(%rsi), %rsp - + CFI_DEF_CFA_REGISTER rsi + leaq ARGOFFSET-RBP(%rsi), %rsp CFI_DEF_CFA_REGISTER rsp - CFI_ADJUST_CFA_OFFSET -16 + CFI_ADJUST_CFA_OFFSET RBP-ARGOFFSET exit_intr: GET_THREAD_INFO(%rcx) -- cgit v1.2.3-18-g5258