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2.6.24-x86: fix assembly of IRQ trampolines

PATCH New Jan Kiszka 1 participant 1 message Jan 24, 2008

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Jan Kiszka

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PATCH 1/1 2.6.24-x86: fix assembly of IRQ trampolines

Only fair that this bug bit me - I introduced the regression:

As we are fiddling with the stack pointer in __ipipe_call_root_*irq_handler, we cannot allow the compiler to fetch arguments from memory with potentially stack-relative addresses. This actually happened with Kyle's minimalistic x86-64 .config here, causing a lockup early during boot. Thus we have to restrict the involved arguments to registers and avoid C-code after the stack pointer was modified.

Jan

Signature · 2 lines
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux
---
 include/asm-x86/ipipe_32.h |    4 ++--
 include/asm-x86/ipipe_64.h |    9 +++++----
 2 files changed, 7 insertions(+), 6 deletions(-)
include/asm-x86/ipipe_32.h +2 -2
Index: b/include/asm-x86/ipipe_32.h
===================================================================
@@ -82,7 +82,7 @@ static inline void __ipipe_call_root_xir
 			     "jmp ret_from_intr\n\t"
 			     "__xirq_end: cli\n"
 			     : /* no output */
-			     : "a" (~irq), "rm" (handler), "rm" (regs));
+			     : "a" (~irq), "r" (handler), "rm" (regs));
 }
 
 void irq_enter(void);

@@ -112,7 +112,7 @@ static inline void __ipipe_call_root_vir
 			     "call *%1\n\t"
 			     "addl $8,%%esp\n"
 			     : /* no output */
-			     : "a" (irq), "rm" (handler), "d" (cookie));
+			     : "a" (irq), "r" (handler), "d" (cookie));
 	irq_exit();
 	__asm__ __volatile__("jmp ret_from_intr\n\t"
 			     "__virq_end: cli\n"
include/asm-x86/ipipe_64.h +5 -4
Index: b/include/asm-x86/ipipe_64.h
===================================================================
@@ -94,7 +94,7 @@ static inline void __ipipe_call_root_xir
 			     : /* no output */
 			     : [kernel_cs] "i" (__KERNEL_CS),
 			       [vector] "rm" (regs->orig_rax),
-			       [handler] "rm" (handler), "D" (regs)
+			       [handler] "r" (handler), "D" (regs)
 			     : "rax");
 }
 

@@ -105,6 +105,7 @@ static inline void __ipipe_call_root_vir
 						  void (*handler)(unsigned, void *),
 						  void *cookie)
 {
+	irq_enter();
 	__asm__ __volatile__("movq  %%rsp, %%rax\n\t"
 			     "pushq $0\n\t"
 			     "pushq %%rax\n\t"

@@ -122,11 +123,11 @@ static inline void __ipipe_call_root_vir
 			     "movq  %%r9,2*8(%%rsp)\n\t"
 			     "movq  %%r10,1*8(%%rsp)\n\t"
 			     "movq  %%r11,(%%rsp)\n\t"
+			     "call  *%[handler]\n\t"
 			     : /* no output */
-			     : [kernel_cs] "i" (__KERNEL_CS)
+			     : [kernel_cs] "i" (__KERNEL_CS),
+			       [handler] "r" (handler), "D" (irq), "S" (cookie)
 			     : "rax");
-	irq_enter();
-	handler(irq, cookie);
 	irq_exit();
 	__asm__ __volatile__("jmp exit_intr\n\t"
 			     "__virq_end: cli\n"