Age | Commit message (Collapse) | Author | Files | Lines | |
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2023-05-18 | x86: Avoid missing-prototype warnings for doublefault code | Arnd Bergmann | 1 | -0/+4 | |
Two functions in the 32-bit doublefault code are lacking a prototype: arch/x86/kernel/doublefault_32.c:23:36: error: no previous prototype for 'doublefault_shim' [-Werror=missing-prototypes] 23 | asmlinkage noinstr void __noreturn doublefault_shim(void) | ^~~~~~~~~~~~~~~~ arch/x86/kernel/doublefault_32.c:114:6: error: no previous prototype for 'doublefault_init_cpu_tss' [-Werror=missing-prototypes] 114 | void doublefault_init_cpu_tss(void) The first one is only called from assembler, while the second one is declared in doublefault.h, but this file is not included. Include the header file and add the other declaration there as well. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com> Link: https://lore.kernel.org/all/20230516193549.544673-8-arnd%40kernel.org | |||||
2020-04-14 | x86/32: Remove CONFIG_DOUBLEFAULT | Borislav Petkov | 1 | -1/+1 | |
Make the doublefault exception handler unconditional on 32-bit. Yes, it is important to be able to catch #DF exceptions instead of silent reboots. Yes, the code size increase is worth every byte. And one less CONFIG symbol is just the cherry on top. No functional changes. Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20200404083646.8897-1-bp@alien8.de | |||||
2019-11-26 | x86/doublefault/32: Move #DF stack and TSS to cpu_entry_area | Andy Lutomirski | 1 | -0/+13 | |
There are three problems with the current layout of the doublefault stack and TSS. First, the TSS is only cacheline-aligned, which is not enough -- if the hardware portion of the TSS (struct x86_hw_tss) crosses a page boundary, horrible things happen [0]. Second, the stack and TSS are global, so simultaneous double faults on different CPUs will cause massive corruption. Third, the whole mechanism won't work if user CR3 is loaded, resulting in a triple fault [1]. Let the doublefault stack and TSS share a page (which prevents the TSS from spanning a page boundary), make it percpu, and move it into cpu_entry_area. Teach the stack dump code about the doublefault stack. [0] Real hardware will read past the end of the page onto the next *physical* page if a task switch happens. Virtual machines may have any number of bugs, and I would consider it reasonable for a VM to summarily kill the guest if it tries to task-switch to a page-spanning TSS. [1] Real hardware triple faults. At least some VMs seem to hang. I'm not sure what's going on. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> |