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Commit 47edb651 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
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x86/asm/msr: Make wrmsrl() a function 



As of cf991de2 ("x86/asm/msr: Make wrmsrl_safe() a
function"), wrmsrl_safe is a function, but wrmsrl is still a
macro.  The wrmsrl macro performs invalid shifts if the value
argument is 32 bits. This makes it unnecessarily awkward to
write code that puts an unsigned long into an MSR.

To make this work, syscall_init needs tweaking to stop passing
a function pointer to wrmsrl.

Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Willy Tarreau <w@1wt.eu>
Link: http://lkml.kernel.org/r/690f0c629a1085d054e2d1ef3da073cfb3f7db92.1437678821.git.luto@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent b466bdb6

arch/x86/include/asm/msr.h

+4 −2
Original line number Diff line number Diff line
@@ -188,8 +188,10 @@ static inline void wrmsr(unsigned msr, unsigned low, unsigned high) 
#define rdmsrl(msr, val)			\

	((val) = native_read_msr((msr)))



#define wrmsrl(msr, val)						\

	native_write_msr((msr), (u32)((u64)(val)), (u32)((u64)(val) >> 32))

static inline void wrmsrl(unsigned msr, u64 val)

{

	native_write_msr(msr, (u32)val, (u32)(val >> 32));

}



/* wrmsr with exception handling */

static inline int wrmsr_safe(unsigned msr, unsigned low, unsigned high)

arch/x86/include/asm/paravirt.h

+5 −1
Original line number Diff line number Diff line
@@ -153,7 +153,11 @@ do { \ 
	val = paravirt_read_msr(msr, &_err);	\

} while (0)



#define wrmsrl(msr, val)	wrmsr(msr, (u32)((u64)(val)), ((u64)(val))>>32)

static inline void wrmsrl(unsigned msr, u64 val)

{

	wrmsr(msr, (u32)val, (u32)(val>>32));

}



#define wrmsr_safe(msr, a, b)	paravirt_write_msr(msr, a, b)



/* rdmsr with exception handling */

arch/x86/kernel/cpu/common.c

+3 −3
Original line number Diff line number Diff line
@@ -1185,10 +1185,10 @@ void syscall_init(void) 
	 * set CS/DS but only a 32bit target. LSTAR sets the 64bit rip.

	 */

	wrmsrl(MSR_STAR,  ((u64)__USER32_CS)<<48  | ((u64)__KERNEL_CS)<<32);

	wrmsrl(MSR_LSTAR, entry_SYSCALL_64);

	wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64);



#ifdef CONFIG_IA32_EMULATION

	wrmsrl(MSR_CSTAR, entry_SYSCALL_compat);

	wrmsrl(MSR_CSTAR, (unsigned long)entry_SYSCALL_compat);

	/*

	 * This only works on Intel CPUs.

	 * On AMD CPUs these MSRs are 32-bit, CPU truncates MSR_IA32_SYSENTER_EIP.
@@ -1199,7 +1199,7 @@ void syscall_init(void) 
	wrmsrl_safe(MSR_IA32_SYSENTER_ESP, 0ULL);

	wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (u64)entry_SYSENTER_compat);

#else

	wrmsrl(MSR_CSTAR, ignore_sysret);

	wrmsrl(MSR_CSTAR, (unsigned long)ignore_sysret);

	wrmsrl_safe(MSR_IA32_SYSENTER_CS, (u64)GDT_ENTRY_INVALID_SEG);

	wrmsrl_safe(MSR_IA32_SYSENTER_ESP, 0ULL);

	wrmsrl_safe(MSR_IA32_SYSENTER_EIP, 0ULL);