From d08452390179710dc7989242605e3c1faa62b64f Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 28 Nov 2018 23:20:07 +0100 Subject: x86/fpu: Use unsigned long long shift in xfeature_uncompacted_offset() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The xfeature mask is 64-bit so a shift from a number to its mask should have ULL suffix or else bits above position 31 will be lost. This is not a problem now but should XFEATURE_MASK_SUPERVISOR gain a bit >31 then this check won't catch it. Use BIT_ULL() to compute a mask from a number. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Borislav Petkov Reviewed-by: Rik van Riel Cc: "H. Peter Anvin" Cc: "Jason A. Donenfeld" Cc: Andy Lutomirski Cc: Dave Hansen Cc: Ingo Molnar Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Thomas Gleixner Cc: kvm ML Cc: x86-ml Link: https://lkml.kernel.org/r/20181128222035.2996-2-bigeasy@linutronix.de --- arch/x86/kernel/fpu/xstate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 87a57b7642d3..69d5740ed254 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -444,7 +444,7 @@ static int xfeature_uncompacted_offset(int xfeature_nr) * format. Checking a supervisor state's uncompacted offset is * an error. */ - if (XFEATURE_MASK_SUPERVISOR & (1 << xfeature_nr)) { + if (XFEATURE_MASK_SUPERVISOR & BIT_ULL(xfeature_nr)) { WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr); return -1; } -- cgit v1.2.3 From e08e32119b944f519664451bfb342a25b4045ead Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 28 Nov 2018 23:20:08 +0100 Subject: x86/process/32: Remove asm/math_emu.h include MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The math_emu.h header files contains the definition of struct math_emu_info which is not used in this file. Remove the asm/math_emu.h include. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Borislav Petkov Reviewed-by: Andy Lutomirski Reviewed-by: Rik van Riel Cc: "H. Peter Anvin" Cc: "Jason A. Donenfeld" Cc: Dave Hansen Cc: Ingo Molnar Cc: Jann Horn Cc: Joerg Roedel Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Rik van Riel Cc: Thomas Gleixner Cc: kvm ML Cc: x86-ml Link: https://lkml.kernel.org/r/20181128222035.2996-3-bigeasy@linutronix.de --- arch/x86/kernel/process_32.c | 3 --- 1 file changed, 3 deletions(-) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index d3e593eb189f..575654db463e 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -44,9 +44,6 @@ #include #include #include -#ifdef CONFIG_MATH_EMULATION -#include -#endif #include -- cgit v1.2.3 From 2f2fcc40a961ed04f0e130803fbaa868c2899310 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 28 Nov 2018 23:20:12 +0100 Subject: x86/fpu: Update comment for __raw_xsave_addr() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The comment above __raw_xsave_addr() claims that the function does not work for compacted buffers and was introduced in: b8b9b6ba9dec3 ("x86/fpu: Allow setting of XSAVE state") In this commit, the function was factored out of get_xsave_addr() and this function claims that it works with "standard format or compacted format of xsave area". It accesses the "xstate_comp_offsets" variable for the actual offset and it was introduced in commit 7496d6458fe32 ("Define kernel API to get address of each state in xsave area") Based on the code (back then and now): - xstate_offsets holds the standard offset. - if compacted mode is not supported then xstate_comp_offsets gets the xstate_offsets copied. - if compacted mode is supported then xstate_comp_offsets will hold the offset for the compacted buffer. Based on that the function works for compacted buffers as long as the CPU supports it and this what we care about. Remove the "Note:" which is not accurate. Suggested-by: Paolo Bonzini Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Borislav Petkov Reviewed-by: Rik van Riel Cc: "H. Peter Anvin" Cc: "Jason A. Donenfeld" Cc: Andy Lutomirski Cc: Dave Hansen Cc: Ingo Molnar Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Thomas Gleixner Cc: kvm ML Cc: x86-ml Link: https://lkml.kernel.org/r/20181128222035.2996-7-bigeasy@linutronix.de --- arch/x86/kernel/fpu/xstate.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 69d5740ed254..359564beab5c 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -808,8 +808,6 @@ void fpu__resume_cpu(void) * Given an xstate feature mask, calculate where in the xsave * buffer the state is. Callers should ensure that the buffer * is valid. - * - * Note: does not work for compacted buffers. */ void *__raw_xsave_addr(struct xregs_state *xsave, int xstate_feature_mask) { -- cgit v1.2.3 From 12209993e98c5fa1855c467f22a24e3d5b8be205 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Thu, 29 Nov 2018 16:02:10 +0100 Subject: x86/fpu: Don't export __kernel_fpu_{begin,end}() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There is one user of __kernel_fpu_begin() and before invoking it, it invokes preempt_disable(). So it could invoke kernel_fpu_begin() right away. The 32bit version of arch_efi_call_virt_setup() and arch_efi_call_virt_teardown() does this already. The comment above *kernel_fpu*() claims that before invoking __kernel_fpu_begin() preemption should be disabled and that KVM is a good example of doing it. Well, KVM doesn't do that since commit f775b13eedee2 ("x86,kvm: move qemu/guest FPU switching out to vcpu_run") so it is not an example anymore. With EFI gone as the last user of __kernel_fpu_{begin|end}(), both can be made static and not exported anymore. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Borislav Petkov Reviewed-by: Rik van Riel Cc: "H. Peter Anvin" Cc: "Jason A. Donenfeld" Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Dave Hansen Cc: Ingo Molnar Cc: Nicolai Stange Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Thomas Gleixner Cc: kvm ML Cc: linux-efi Cc: x86-ml Link: https://lkml.kernel.org/r/20181129150210.2k4mawt37ow6c2vq@linutronix.de --- arch/x86/include/asm/efi.h | 6 ++---- arch/x86/include/asm/fpu/api.h | 15 +++++---------- arch/x86/kernel/fpu/core.c | 6 ++---- 3 files changed, 9 insertions(+), 18 deletions(-) (limited to 'arch/x86/kernel') diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h index eea40d52ca78..45864898f7e5 100644 --- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -82,8 +82,7 @@ struct efi_scratch { #define arch_efi_call_virt_setup() \ ({ \ efi_sync_low_kernel_mappings(); \ - preempt_disable(); \ - __kernel_fpu_begin(); \ + kernel_fpu_begin(); \ firmware_restrict_branch_speculation_start(); \ \ if (!efi_enabled(EFI_OLD_MEMMAP)) \ @@ -99,8 +98,7 @@ struct efi_scratch { efi_switch_mm(efi_scratch.prev_mm); \ \ firmware_restrict_branch_speculation_end(); \ - __kernel_fpu_end(); \ - preempt_enable(); \ + kernel_fpu_end(); \ }) extern void __iomem *__init efi_ioremap(unsigned long addr, unsigned long size, diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h index a9caac9d4a72..b56d504af654 100644 --- a/arch/x86/include/asm/fpu/api.h +++ b/arch/x86/include/asm/fpu/api.h @@ -12,17 +12,12 @@ #define _ASM_X86_FPU_API_H /* - * Careful: __kernel_fpu_begin/end() must be called with preempt disabled - * and they don't touch the preempt state on their own. - * If you enable preemption after __kernel_fpu_begin(), preempt notifier - * should call the __kernel_fpu_end() to prevent the kernel/user FPU - * state from getting corrupted. KVM for example uses this model. - * - * All other cases use kernel_fpu_begin/end() which disable preemption - * during kernel FPU usage. + * Use kernel_fpu_begin/end() if you intend to use FPU in kernel context. It + * disables preemption so be careful if you intend to use it for long periods + * of time. + * If you intend to use the FPU in softirq you need to check first with + * irq_fpu_usable() if it is possible. */ -extern void __kernel_fpu_begin(void); -extern void __kernel_fpu_end(void); extern void kernel_fpu_begin(void); extern void kernel_fpu_end(void); extern bool irq_fpu_usable(void); diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 2ea85b32421a..2e5003fef51a 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -93,7 +93,7 @@ bool irq_fpu_usable(void) } EXPORT_SYMBOL(irq_fpu_usable); -void __kernel_fpu_begin(void) +static void __kernel_fpu_begin(void) { struct fpu *fpu = ¤t->thread.fpu; @@ -111,9 +111,8 @@ void __kernel_fpu_begin(void) __cpu_invalidate_fpregs_state(); } } -EXPORT_SYMBOL(__kernel_fpu_begin); -void __kernel_fpu_end(void) +static void __kernel_fpu_end(void) { struct fpu *fpu = ¤t->thread.fpu; @@ -122,7 +121,6 @@ void __kernel_fpu_end(void) kernel_fpu_enable(); } -EXPORT_SYMBOL(__kernel_fpu_end); void kernel_fpu_begin(void) { -- cgit v1.2.3