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Revert "perf,x86: avoid missing caller address in stack traces captured in uprobe"

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This reverts commit adf290fe43 which is
commit cfa7f3d2c5 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I4912c7be5dce01570c374c4018de1da6ce5dab3b
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
This commit is contained in:
Greg Kroah-Hartman 2024-10-10 13:03:47 +00:00
parent ac723e338f
commit ae4370b575
3 changed files with 0 additions and 67 deletions
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63
arch/x86/events/core.c
View File

@ -41,8 +41,6 @@
#include <asm/desc.h>
#include <asm/ldt.h>
#include <asm/unwind.h>
#include <asm/uprobes.h>
#include <asm/ibt.h>
#include "perf_event.h"
@ -2818,46 +2816,6 @@ static unsigned long get_segment_base(unsigned int segment)
return get_desc_base(desc);
}
#ifdef CONFIG_UPROBES
/*
* Heuristic-based check if uprobe is installed at the function entry.
*
* Under assumption of user code being compiled with frame pointers,
* `push %rbp/%ebp` is a good indicator that we indeed are.
*
* Similarly, `endbr64` (assuming 64-bit mode) is also a common pattern.
* If we get this wrong, captured stack trace might have one extra bogus
* entry, but the rest of stack trace will still be meaningful.
*/
static bool is_uprobe_at_func_entry(struct pt_regs *regs)
{
struct arch_uprobe *auprobe;
if (!current->utask)
return false;
auprobe = current->utask->auprobe;
if (!auprobe)
return false;
/* push %rbp/%ebp */
if (auprobe->insn[0] == 0x55)
return true;
/* endbr64 (64-bit only) */
if (user_64bit_mode(regs) && is_endbr(*(u32 *)auprobe->insn))
return true;
return false;
}
#else
static bool is_uprobe_at_func_entry(struct pt_regs *regs)
{
return false;
}
#endif /* CONFIG_UPROBES */
#ifdef CONFIG_IA32_EMULATION
#include <linux/compat.h>
@ -2869,7 +2827,6 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
unsigned long ss_base, cs_base;
struct stack_frame_ia32 frame;
const struct stack_frame_ia32 __user *fp;
u32 ret_addr;
if (user_64bit_mode(regs))
return 0;
@ -2879,12 +2836,6 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry_ctx *ent
fp = compat_ptr(ss_base + regs->bp);
pagefault_disable();
/* see perf_callchain_user() below for why we do this */
if (is_uprobe_at_func_entry(regs) &&
!get_user(ret_addr, (const u32 __user *)regs->sp))
perf_callchain_store(entry, ret_addr);
while (entry->nr < entry->max_stack) {
if (!valid_user_frame(fp, sizeof(frame)))
break;
@ -2913,7 +2864,6 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
{
struct stack_frame frame;
const struct stack_frame __user *fp;
unsigned long ret_addr;
if (perf_guest_state()) {
/* TODO: We don't support guest os callchain now */
@ -2937,19 +2887,6 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs
return;
pagefault_disable();
/*
* If we are called from uprobe handler, and we are indeed at the very
* entry to user function (which is normally a `push %rbp` instruction,
* under assumption of application being compiled with frame pointers),
* we should read return address from *regs->sp before proceeding
* to follow frame pointers, otherwise we'll skip immediate caller
* as %rbp is not yet setup.
*/
if (is_uprobe_at_func_entry(regs) &&
!get_user(ret_addr, (const unsigned long __user *)regs->sp))
perf_callchain_store(entry, ret_addr);
while (entry->nr < entry->max_stack) {
if (!valid_user_frame(fp, sizeof(frame)))
break;

2
include/linux/uprobes.h
View File

@ -76,8 +76,6 @@ struct uprobe_task {
struct uprobe *active_uprobe;
unsigned long xol_vaddr;
struct arch_uprobe *auprobe;
struct return_instance *return_instances;
unsigned int depth;
};

2
kernel/events/uprobes.c
View File

@ -2075,7 +2075,6 @@ static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
bool need_prep = false; /* prepare return uprobe, when needed */
down_read(&uprobe->register_rwsem);
current->utask->auprobe = &uprobe->arch;
for (uc = uprobe->consumers; uc; uc = uc->next) {
int rc = 0;
@ -2090,7 +2089,6 @@ static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
remove &= rc;
}
current->utask->auprobe = NULL;
if (need_prep && !remove)
prepare_uretprobe(uprobe, regs); /* put bp at return */