redonkable/remarkable-linux
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[PATCH] uml: stack usage reduction

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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>
This commit is contained in:
Jeff Dike 2006-09-25 23:33:08 -07:00 committed by Linus Torvalds
parent bf61f50d63
commit 75e29b18d9
5 changed files with 21 additions and 17 deletions
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3
arch/um/include/registers.h
View file

@ -7,6 +7,7 @@
#define __REGISTERS_H
#include "sysdep/ptrace.h"
#include "sysdep/archsetjmp.h"
extern void init_thread_registers(union uml_pt_regs *to);
extern int save_fp_registers(int pid, unsigned long *fp_regs);
@ -15,6 +16,6 @@ extern void save_registers(int pid, union uml_pt_regs *regs);
extern void restore_registers(int pid, union uml_pt_regs *regs);
extern void init_registers(int pid);
extern void get_safe_registers(unsigned long * regs, unsigned long * fp_regs);
extern void get_thread_regs(union uml_pt_regs *uml_regs, void *buffer);
extern unsigned long get_thread_reg(int reg, jmp_buf *buf);
#endif

1
arch/um/os-Linux/start_up.c
View file

@ -14,7 +14,6 @@
#include <sched.h>
#include <fcntl.h>
#include <errno.h>
#include <setjmp.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/mman.h>

15
arch/um/os-Linux/sys-i386/registers.c
View file

@ -130,11 +130,14 @@ void get_safe_registers(unsigned long *regs, unsigned long *fp_regs)
HOST_FP_SIZE * sizeof(unsigned long));
}
void get_thread_regs(union uml_pt_regs *uml_regs, void *buffer)
unsigned long get_thread_reg(int reg, jmp_buf *buf)
{
struct __jmp_buf *jmpbuf = buffer;
UPT_SET(uml_regs, EIP, jmpbuf->__eip);
UPT_SET(uml_regs, UESP, jmpbuf->__esp);
UPT_SET(uml_regs, EBP, jmpbuf->__ebp);
switch(reg){
case EIP: return buf[0]->__eip;
case UESP: return buf[0]->__esp;
case EBP: return buf[0]->__ebp;
default:
printk("get_thread_regs - unknown register %d\n", reg);
return 0;
}
}

15
arch/um/os-Linux/sys-x86_64/registers.c
View file

@ -78,11 +78,14 @@ void get_safe_registers(unsigned long *regs, unsigned long *fp_regs)
HOST_FP_SIZE * sizeof(unsigned long));
}
void get_thread_regs(union uml_pt_regs *uml_regs, void *buffer)
unsigned long get_thread_reg(int reg, jmp_buf *buf)
{
struct __jmp_buf *jmpbuf = buffer;
UPT_SET(uml_regs, RIP, jmpbuf->__rip);
UPT_SET(uml_regs, RSP, jmpbuf->__rsp);
UPT_SET(uml_regs, RBP, jmpbuf->__rbp);
switch(reg){
case RIP: return buf[0]->__rip;
case RSP: return buf[0]->__rsp;
case RBP: return buf[0]->__rbp;
default:
printk("get_thread_regs - unknown register %d\n", reg);
return 0;
}
}

4
include/asm-um/processor-generic.h
View file

@ -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