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Commit 489745f2 authored by Cyrill Gorcunov's avatar Cyrill Gorcunov
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restore: A number of fixups and debug printing 

An idea is to align restorer size to be sure it
wont be stripped in a middle of code.
Signed-off-by: 's avatarCyrill Gorcunov <gorcunov@gmail.com>
parent ed3c4fba
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Showing with 90 additions and 27 deletions
Makefile
View file @ 489745f2
......@@ -23,7 +23,7 @@ MAKE := make
CFLAGS += -I./include
CFLAGS += -O0 -ggdb3
LIBS += -lrt
LIBS += -lrt -lpthread
# Additional ARCH settings for x86
ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \
......@@ -109,7 +109,7 @@ $(OBJS): $(HEAD-BLOB) $(DEPS) $(HEAD-BLOB-GEN)
$(E) " CC " $@
$(Q) $(CC) -c $(CFLAGS) $< -o $@
$(PROGRAM): $(OBJS)
$(PROGRAM): $(OBJS) restorer.o
$(E) " LINK " $@
$(Q) $(CC) $(CFLAGS) $(OBJS) $(LIBS) -o $@
......@@ -124,6 +124,13 @@ test:
$(Q) $(MAKE) -C test all
.PHONY: test
rebuild:
$(E) " FORCE-REBUILD"
$(Q) $(RM) -f ./*.o
$(Q) $(RM) -f ./*.d
$(Q) $(MAKE)
.PHONY: rebuild
clean:
$(E) " CLEAN"
$(Q) $(RM) -f ./*.o
......
cr-restore.c
View file @ 489745f2
......@@ -1262,7 +1262,7 @@ static void restorer_test(pid_t pid)
code_len = restorer_fcall(RESTORER_CMD__GET_SELF_LEN) - (long)restorer;
args_offset = restorer_fcall(RESTORER_CMD__GET_ARG_OFFSET) - (long)restorer;
code_len = round_up(code_len, 16);
vma_len = round_up(code_len + RESTORER_STACK_SIZE, PAGE_SIZE);
vma_len = round_up(code_len + RESTORER_STACK_SIZE + RESTORER_STACK_FRAME, PAGE_SIZE);
/*
* Here we need some heuristics -- the VMA which restorer will
......@@ -1280,28 +1280,30 @@ static void restorer_test(pid_t pid)
return;
}
/*
* Prepare a stack for the restorer. It's a bit
* tricky -- since compiler generates function
* prologue we need to manually tune up stack
* value.
*/
exec_start = exec_mem + RESTORER_STACK_SIZE;
memzero(exec_mem, RESTORER_STACK_SIZE);
memzero(exec_mem, RESTORER_STACK_SIZE + RESTORER_STACK_FRAME);
exec_start = exec_mem + RESTORER_STACK_SIZE + RESTORER_STACK_FRAME;
/* Restorer content at the new location */
memcpy(exec_start, &restorer, code_len);
restorer_fcall = exec_start;
/*
* Stack pointer in a middle of allocated stack zone.
* Adjust stack with red-zone area.
*/
new_sp = (long)exec_mem + RESTORER_STACK_MIDDLE;
new_sp = (long)exec_mem + RESTORER_STACK_SIZE - RESTORER_STACK_REDZONE;
/*
* Pass arguments and run a command.
*/
args = (struct restore_core_args *)(exec_start + args_offset);
args->rt_sigframe = (void *)((long)exec_mem + RESTORER_STACK_SIZE + RESTORER_STACK_REDZONE);
args->self_entry = exec_mem;
args->self_size = vma_len;
......@@ -1310,6 +1312,14 @@ static void restorer_test(pid_t pid)
snprintf(path, sizeof(path), "core-%d.img", pid);
strcpy(args->core_path, path);
pr_info("vma_len: %li code_len: %li exec_mem: %p exec_start: %p new_sp: %p args: %p\n",
vma_len, code_len, exec_mem, exec_start, new_sp, args);
pr_info("args: %p args->rt_sigframe: %p args->self_entry: %p \nargs->self_size: %p "
"args->self_vmas_path: %p args->core_path: %p\n",
args, args->rt_sigframe, args->self_entry, args->self_size,
args->self_vmas_path, args->core_path);
/*
* An indirect call to restorer, note it never resturns
* and restoreing core is extremely destructive.
......
include/restorer.h
View file @ 489745f2
......@@ -12,10 +12,11 @@
#endif
#define RESTORER_ARGS_SIZE 512
#define RESTORER_STACK_MIDDLE (16 << 10)
#define RESTORER_STACK_SIZE (RESTORER_STACK_MIDDLE * 2)
#define RESTORER_STACK_REDZONE (128)
#define RESTORER_STACK_FRAME (16 << 10)
#define RESTORER_STACK_SIZE (32 << 10)
long restorer(long cmd);
extern long restorer(long cmd);
typedef long (*restorer_fcall_t) (long cmd);
......@@ -27,18 +28,61 @@ typedef long (*restorer_fcall_t) (long cmd);
#define ABI_RED_ZONE 128
#define align_sigframe(sp) \
do { \
sp = round_down(sp, 16) - 8; \
} while (0)
#define align_sigframe(sp) round_down(sp, 16) - 8
struct restore_core_args {
void *self_entry; /* restorer placed at */
void *rt_sigframe; /* sigframe placed at */
long self_size; /* size for restorer granted */
char core_path[64]; /* path to a core file */
char self_vmas_path[64]; /* path to a self-vmas file */
};
struct pt_regs {
unsigned long r15;
unsigned long r14;
unsigned long r13;
unsigned long r12;
unsigned long bp;
unsigned long bx;
unsigned long r11;
unsigned long r10;
unsigned long r9;
unsigned long r8;
unsigned long ax;
unsigned long cx;
unsigned long dx;
unsigned long si;
unsigned long di;
unsigned long orig_ax;
unsigned long ip;
unsigned long cs;
unsigned long flags;
unsigned long sp;
unsigned long ss;
};
struct partial_pt_regs {
unsigned long r11;
unsigned long r10;
unsigned long r9;
unsigned long r8;
unsigned long ax;
unsigned long cx;
unsigned long dx;
unsigned long si;
unsigned long di;
unsigned long orig_ax;
unsigned long ip;
unsigned long cs;
unsigned long flags;
unsigned long sp;
unsigned long ss;
};
struct rt_sigcontext {
unsigned long r8;
unsigned long r9;
......
restorer.c
View file @ 489745f2
......@@ -42,6 +42,8 @@
#define inline_memzero(d,l) __builtin_memset(d,0,l)
#define inline_memzero_p(d) __builtin_memset(d,0,sizeof(*(d)))
#define sigframe_addr(p) ((long)p)
static void always_inline write_char(char c)
{
sys_write(1, &c, 1);
......@@ -67,7 +69,6 @@ static void always_inline write_string_n(char *str)
static void always_inline write_hex_n(unsigned long num)
{
bool tailing = false;
unsigned char *s = (unsigned char *)&num;
unsigned char c;
int i;
......@@ -152,6 +153,8 @@ self_len_end:
struct user_regs_entry *gpregs;
struct rt_sigframe *rt_sigframe;
unsigned long new_sp, *stack;
lea_args_off(args);
write_string_n(args->core_path);
......@@ -296,13 +299,9 @@ self_len_end:
* by the kernel with stack overflow error.
*/
/*
* Reuse arguments space for own needs,
* no more arguments needed so lets try
* to be thrifty with memory usage.
*/
lea_args_off(rt_sigframe);
inline_memzero_p(rt_sigframe);
rt_sigframe = args->rt_sigframe;
write_hex_n((long)rt_sigframe);
write_hex_n((long)&rt_sigframe->uc);
#define CPREG1(d) rt_sigframe->uc.uc_mcontext.d = core_entry.u.arch.gpregs.d
#define CPREG2(d,s) rt_sigframe->uc.uc_mcontext.d = core_entry.u.arch.gpregs.s
......@@ -331,7 +330,10 @@ self_len_end:
/* FIXME: What with cr2 and friends which are rest there? */
write_hex_n(__LINE__);
new_sp = core_entry.u.arch.gpregs.sp - 8;
write_hex_n(new_sp);
stack = (void *)new_sp;
*stack = (long)rt_sigframe;
/*
* Prepare the stack and call for sigreturn,
......@@ -344,7 +346,7 @@ self_len_end:
"movl $"__stringify(__NR_rt_sigreturn)", %%eax \t\n"
"syscall \t\n"
:
: "r"((long)rt_sigframe + sizeof(*rt_sigframe))
: "r"(new_sp)
: "rax","rsp","memory");
core_restore_end:
......@@ -364,11 +366,11 @@ core_restore_end:
self_len_start:
asm volatile(
".align 16 \t\n"
".align 64 \t\n"
"self: \t\n"
"leaq self(%%rip), %%rax \t\n"
"addq $16, %%rax \t\n"
"andq $~15, %%rax \t\n"
"addq $64, %%rax \t\n"
"andq $~63, %%rax \t\n"
"movq %%rax, %0 \t\n"
: "=r"(ret)
:
......
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