Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'x86_core_for_v6.0_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 core updates from Borislav Petkov:
- Have invalid MSR accesses warnings appear only once after a
pr_warn_once() change broke that
- Simplify {JMP,CALL}_NOSPEC and let the objtool retpoline patching
infra take care of them instead of having unreadable alternative
macros there
* tag 'x86_core_for_v6.0_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/extable: Fix ex_handler_msr() print condition
x86,nospec: Simplify {JMP,CALL}_NOSPEC
+43
-17
+18
-6
arch/x86/include/asm/nospec-branch.h
+18
-6
arch/x86/include/asm/nospec-branch.h
···
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.endm
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/*
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* Equivalent to -mindirect-branch-cs-prefix; emit the 5 byte jmp/call
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* to the retpoline thunk with a CS prefix when the register requires
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* a RAX prefix byte to encode. Also see apply_retpolines().
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*/
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.macro __CS_PREFIX reg:req
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.irp rs,r8,r9,r10,r11,r12,r13,r14,r15
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.ifc \reg,\rs
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.byte 0x2e
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.endif
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.endr
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.endm
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+
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/*
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* JMP_NOSPEC and CALL_NOSPEC macros can be used instead of a simple
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* indirect jmp/call which may be susceptible to the Spectre variant 2
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* attack.
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*/
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.macro JMP_NOSPEC reg:req
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#ifdef CONFIG_RETPOLINE
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ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), \
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__stringify(jmp __x86_indirect_thunk_\reg), X86_FEATURE_RETPOLINE, \
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__stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), X86_FEATURE_RETPOLINE_LFENCE
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__CS_PREFIX \reg
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jmp __x86_indirect_thunk_\reg
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#else
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jmp *%\reg
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int3
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#endif
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.endm
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.macro CALL_NOSPEC reg:req
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#ifdef CONFIG_RETPOLINE
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ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; call *%\reg), \
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__stringify(call __x86_indirect_thunk_\reg), X86_FEATURE_RETPOLINE, \
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-
__stringify(lfence; ANNOTATE_RETPOLINE_SAFE; call *%\reg), X86_FEATURE_RETPOLINE_LFENCE
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__CS_PREFIX \reg
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call __x86_indirect_thunk_\reg
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#else
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call *%\reg
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#endif
+9
-7
arch/x86/mm/extable.c
+9
-7
arch/x86/mm/extable.c
···
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static bool ex_handler_msr(const struct exception_table_entry *fixup,
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struct pt_regs *regs, bool wrmsr, bool safe, int reg)
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{
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if (!safe && wrmsr &&
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pr_warn_once("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pS)\n",
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(unsigned int)regs->cx, (unsigned int)regs->dx,
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(unsigned int)regs->ax, regs->ip, (void *)regs->ip))
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if (__ONCE_LITE_IF(!safe && wrmsr)) {
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pr_warn("unchecked MSR access error: WRMSR to 0x%x (tried to write 0x%08x%08x) at rIP: 0x%lx (%pS)\n",
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(unsigned int)regs->cx, (unsigned int)regs->dx,
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(unsigned int)regs->ax, regs->ip, (void *)regs->ip);
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show_stack_regs(regs);
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}
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if (!safe && !wrmsr &&
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pr_warn_once("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pS)\n",
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(unsigned int)regs->cx, regs->ip, (void *)regs->ip))
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if (__ONCE_LITE_IF(!safe && !wrmsr)) {
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pr_warn("unchecked MSR access error: RDMSR from 0x%x at rIP: 0x%lx (%pS)\n",
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(unsigned int)regs->cx, regs->ip, (void *)regs->ip);
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show_stack_regs(regs);
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}
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if (!wrmsr) {
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/* Pretend that the read succeeded and returned 0. */
+16
-4
include/linux/once_lite.h
+16
-4
include/linux/once_lite.h
···
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*/
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#define DO_ONCE_LITE(func, ...) \
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DO_ONCE_LITE_IF(true, func, ##__VA_ARGS__)
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#define DO_ONCE_LITE_IF(condition, func, ...) \
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#define __ONCE_LITE_IF(condition) \
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({ \
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static bool __section(".data.once") __already_done; \
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bool __ret_cond = !!(condition); \
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bool __ret_once = false; \
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\
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if (unlikely(__ret_cond && !__already_done)) { \
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__already_done = true; \
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__ret_once = true; \
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} \
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unlikely(__ret_once); \
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})
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+
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#define DO_ONCE_LITE_IF(condition, func, ...) \
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({ \
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bool __ret_do_once = !!(condition); \
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\
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-
if (unlikely(__ret_do_once && !__already_done)) { \
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__already_done = true; \
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if (__ONCE_LITE_IF(__ret_do_once)) \
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func(__VA_ARGS__); \
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} \
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\
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unlikely(__ret_do_once); \
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})
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