[PATCH] uml: stack usage reduction

The KSTK_* macros used an inordinate amount of stack.  In order to overcome
an impedance mismatch between their interface, which just returns a single
register value, and the interface of get_thread_regs, which took a full
pt_regs, the implementation created an on-stack pt_regs, filled it in, and
returned one field.  do_task_stat calls KSTK_* twice, resulting in two
local pt_regs, blowing out the stack.

This patch changes the interface (and name) of get_thread_regs to just
return a single register from a jmp_buf.

The include of archsetjmp.h" in registers.h to get the definition of
jmp_buf exposed a bogus include of <setjmp.h> in start_up.c.  <setjmp.h>
shouldn't be used anywhere any more since UML uses the klibc
setjmp/longjmp.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 3 deletions

diff --git a/include/asm-um/processor-generic.h b/include/asm-um/processor-generic.h
index 824c2889638..afa4fe1ca9f 100644
--- a/include/asm-um/processor-generic.h
+++ b/include/asm-um/processor-generic.h
@@ -138,9 +138,7 @@ extern struct cpuinfo_um cpu_data[];
 
 #ifdef CONFIG_MODE_SKAS
 #define KSTK_REG(tsk, reg) \
-        ({ union uml_pt_regs regs; \
-           get_thread_regs(&regs, tsk->thread.mode.skas.switch_buf); \
-           UPT_REG(&regs, reg); })
+        get_thread_reg(reg, tsk->thread.mode.skas.switch_buf)
 #else
 #define KSTK_REG(tsk, reg) (0xbadbabe)
 #endif