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s390/stackstrace: Detect vdso stack frames

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Clear the backchain of the extra stack frame added by the vdso user wrapper
code. This allows the user stack walker to detect and skip the non-standard
stack frame. Without this an incorrect instruction pointer would be added
to stack traces, and stack frame walking would be continued with a more or
less random back chain.

Fixes: aa44433ac4ee ("s390: add USER_STACKTRACE support")
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2024-04-29 14:28:48 +02:00 committed by Alexander Gordeev
parent be72ea09c1
commit 62b672c4ba
5 changed files with 36 additions and 8 deletions
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1
arch/s390/include/asm/processor.h
View File

@ -98,6 +98,7 @@ void cpu_detect_mhz_feature(void);
extern const struct seq_operations cpuinfo_op;
extern void execve_tail(void);
unsigned long vdso_text_size(void);
unsigned long vdso_size(void);
/*

1
arch/s390/kernel/asm-offsets.c
View File

@ -66,6 +66,7 @@ int main(void)
OFFSET(__SF_SIE_CONTROL_PHYS, stack_frame, sie_control_block_phys);
DEFINE(STACK_FRAME_OVERHEAD, sizeof(struct stack_frame));
BLANK();
OFFSET(__SFUSER_BACKCHAIN, stack_frame_user, back_chain);
DEFINE(STACK_FRAME_USER_OVERHEAD, sizeof(struct stack_frame_user));
OFFSET(__SFVDSO_RETURN_ADDRESS, stack_frame_vdso_wrapper, return_address);
DEFINE(STACK_FRAME_VDSO_OVERHEAD, sizeof(struct stack_frame_vdso_wrapper));

28
arch/s390/kernel/stacktrace.c
View File

@ -92,10 +92,16 @@ static inline bool ip_invalid(unsigned long ip)
return false;
}
static inline bool ip_within_vdso(unsigned long ip)
{
return in_range(ip, current->mm->context.vdso_base, vdso_text_size());
}
void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *cookie,
struct perf_callchain_entry_ctx *entry,
const struct pt_regs *regs, bool perf)
{
struct stack_frame_vdso_wrapper __user *sf_vdso;
struct stack_frame_user __user *sf;
unsigned long ip, sp;
bool first = true;
@ -112,11 +118,25 @@ void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *coo
while (1) {
if (__get_user(sp, &sf->back_chain))
break;
/*
* VDSO entry code has a non-standard stack frame layout.
* See VDSO user wrapper code for details.
*/
if (!sp && ip_within_vdso(ip)) {
sf_vdso = (void __user *)sf;
if (__get_user(ip, &sf_vdso->return_address))
break;
sp = (unsigned long)sf + STACK_FRAME_VDSO_OVERHEAD;
sf = (void __user *)sp;
if (__get_user(sp, &sf->back_chain))
break;
} else {
sf = (void __user *)sp;
if (__get_user(ip, &sf->gprs[8]))
break;
}
/* Sanity check: ABI requires SP to be 8 byte aligned. */
if (!sp || sp & 0x7)
break;
sf = (void __user *)sp;
if (__get_user(ip, &sf->gprs[8]))
if (sp & 0x7)
break;
if (ip_invalid(ip)) {
/*

13
arch/s390/kernel/vdso.c
View File

@ -210,17 +210,22 @@ static unsigned long vdso_addr(unsigned long start, unsigned long len)
return addr;
}
unsigned long vdso_size(void)
unsigned long vdso_text_size(void)
{
unsigned long size = VVAR_NR_PAGES * PAGE_SIZE;
unsigned long size;
if (is_compat_task())
size += vdso32_end - vdso32_start;
size = vdso32_end - vdso32_start;
else
size += vdso64_end - vdso64_start;
size = vdso64_end - vdso64_start;
return PAGE_ALIGN(size);
}
unsigned long vdso_size(void)
{
return vdso_text_size() + VVAR_NR_PAGES * PAGE_SIZE;
}
int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
unsigned long addr = VDSO_BASE;

1
arch/s390/kernel/vdso64/vdso_user_wrapper.S
View File

@ -23,6 +23,7 @@ __kernel_\func:
CFI_VAL_OFFSET 15,-STACK_FRAME_USER_OVERHEAD
stg %r14,__SFVDSO_RETURN_ADDRESS(%r15)
CFI_REL_OFFSET 14,__SFVDSO_RETURN_ADDRESS
xc __SFUSER_BACKCHAIN(8,%r15),__SFUSER_BACKCHAIN(%r15)
brasl %r14,__s390_vdso_\func
lg %r14,__SFVDSO_RETURN_ADDRESS(%r15)
CFI_RESTORE 14