i386: Make CMPXCHG64 only dependent on PAE

PATCH New Andi Kleen 1 participant 3 messages Jun 23, 2007 Linux for power macintosh

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Andi Kleen

author

2007-06-23 00:29 UTC #0 lore raw

PATCH 1/3 i386: Make CMPXCHG64 only dependent on PAE

It is only used for PAE kernels in set_64bit.

The problem is that due to a old Windows bug many CPUs need magic MSRs to enable CMPXCHG64, and we can't do that nicely early enough before it is potentially used.

But since we only need it in PAE kernels so only force the checking for CMPXCHG65 with PAE.

This fixes a boot failure on Transmeta Crusoe

Signed-off-by Andi Kleen <[email protected]>

---
 arch/i386/Kconfig.cpu |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

arch/i386/Kconfig.cpu +1 -1

Index: linux/arch/i386/Kconfig.cpu
===================================================================
@@ -299,7 +299,7 @@ config X86_POPAD_OK
 
 config X86_CMPXCHG64
 	bool
-	depends on !M386 && !M486
+	depends on X86_PAE
 	default y
 
 config X86_ALIGNMENT_16

arch/i386/Kconfig +1 -1

Index: linux/arch/i386/Kconfig
===================================================================
@@ -541,7 +541,7 @@ config HIGHMEM4G
 
 config HIGHMEM64G
 	bool "64GB"
-	depends on X86_CMPXCHG64
+	depends on !M386 && !M486
 	help
 	  Select this if you have a 32-bit processor and more than 4
 	  gigabytes of physical RAM.

Andi Kleen

author

2007-06-23 00:30 UTC #1 lore raw

PATCH 2/3 x86_64: Fix only make Macintosh drivers default on Macs

From: Olaf Hering <[email protected]>

Include PPC_MAC in the default too, not only MAC which only covers m68k MACs.

Signed-off-by Olaf Hering <[email protected]>

Signed-off-by Andi Kleen <[email protected]>

---
 drivers/macintosh/Kconfig |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

drivers/macintosh/Kconfig +1 -1

Index: linux/drivers/macintosh/Kconfig
===================================================================
@@ -2,7 +2,7 @@
 menuconfig MACINTOSH_DRIVERS
 	bool "Macintosh device drivers"
 	depends on PPC || MAC || X86
-	default y if MAC
+	default y if (PPC_PMAC || MAC)
 
 if MACINTOSH_DRIVERS

Andi Kleen

author

2007-06-23 00:29 UTC #2 lore raw

PATCH 3/3 x86_64: Ignore compat mode SYSCALL when IA32_EMULATION is not defined

In reply to Andi Kleen

Previously a program could switch to a compat mode segment and then execute SYSCALL and it would jump to an uninitialized MSR and crash the kernel.

Instead supply a dummy target for this case.

Pointed out by Jan Beulich

Cc [email protected]

Signed-off-by Andi Kleen <[email protected]>

---
 arch/x86_64/kernel/entry.S   |    7 +++++++
 arch/x86_64/kernel/setup64.c |    3 +++
 2 files changed, 10 insertions(+)

arch/x86_64/kernel/entry.S +7 -0

Index: linux/arch/x86_64/kernel/entry.S
===================================================================
@@ -1163,3 +1163,10 @@ ENTRY(call_softirq)
 	ret
 	CFI_ENDPROC
 ENDPROC(call_softirq)
+
+KPROBE_ENTRY(ignore_sysret)
+	CFI_STARTPROC
+	mov $-ENOSYS,%eax
+	sysret
+	CFI_ENDPROC
+ENDPROC(ignore_sysret)

arch/x86_64/kernel/setup64.c +3 -0

Index: linux/arch/x86_64/kernel/setup64.c
===================================================================
@@ -150,6 +150,8 @@ void pda_init(int cpu)
 char boot_exception_stacks[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]
 __attribute__((section(".bss.page_aligned")));
 
+extern asmlinkage void ignore_sysret(void);
+
 /* May not be marked __init: used by software suspend */
 void syscall_init(void)
 {

@@ -160,6 +162,7 @@ void syscall_init(void)
 	 */ 
 	wrmsrl(MSR_STAR,  ((u64)__USER32_CS)<<48  | ((u64)__KERNEL_CS)<<32); 
 	wrmsrl(MSR_LSTAR, system_call); 
+	wrmsrl(MSR_CSTAR, ignore_sysret);
 
 #ifdef CONFIG_IA32_EMULATION   		
 	syscall32_cpu_init ();