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x86/entry: Unbreak __irqentry_text_start/end magic

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The entry rework moved interrupt entry code from the irqentry to the
noinstr section which made the irqentry section empty.

This breaks boundary checks which rely on the __irqentry_text_start/end
markers to find out whether a function in a stack trace is
interrupt/exception entry code. This affects the function graph tracer and
filter_irq_stacks().

As the IDT entry points are all sequentialy emitted this is rather simple
to unbreak by injecting __irqentry_text_start/end as global labels.

To make this work correctly:

  - Remove the IRQENTRY_TEXT section from the x86 linker script
  - Define __irqentry so it breaks the build if it's used
  - Adjust the entry mirroring in PTI
  - Remove the redundant kprobes and unwinder bound checks

Reported-by: Qian Cai <cai@lca.pw>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner
2020-06-10 08:37:01 +02:00
parent 2823e83a3d
commit f0178fc01f
9 changed files with 36 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
arch/x86/kernel/kprobes/core.c
View File

@@ -1073,13 +1073,6 @@ NOKPROBE_SYMBOL(kprobe_fault_handler);
int __init arch_populate_kprobe_blacklist(void)
{
int ret;
ret = kprobe_add_area_blacklist((unsigned long)__irqentry_text_start,
(unsigned long)__irqentry_text_end);
if (ret)
return ret;
return kprobe_add_area_blacklist((unsigned long)__entry_text_start,
(unsigned long)__entry_text_end);
}

4
arch/x86/kernel/kprobes/opt.c
View File

@@ -286,9 +286,7 @@ static int can_optimize(unsigned long paddr)
* stack handling and registers setup.
*/
if (((paddr >= (unsigned long)__entry_text_start) &&
(paddr < (unsigned long)__entry_text_end)) ||
((paddr >= (unsigned long)__irqentry_text_start) &&
(paddr < (unsigned long)__irqentry_text_end)))
(paddr < (unsigned long)__entry_text_end)))
return 0;
/* Check there is enough space for a relative jump. */

8
arch/x86/kernel/unwind_frame.c
View File

@@ -74,13 +74,7 @@ static bool in_entry_code(unsigned long ip)
{
char *addr = (char *)ip;
if (addr >= __entry_text_start && addr < __entry_text_end)
return true;
if (addr >= __irqentry_text_start && addr < __irqentry_text_end)
return true;
return false;
return addr >= __entry_text_start && addr < __entry_text_end;
}
static inline unsigned long *last_frame(struct unwind_state *state)

1
arch/x86/kernel/vmlinux.lds.S
View File

@@ -134,7 +134,6 @@ SECTIONS
KPROBES_TEXT
ALIGN_ENTRY_TEXT_BEGIN
ENTRY_TEXT
IRQENTRY_TEXT
ALIGN_ENTRY_TEXT_END
SOFTIRQENTRY_TEXT
*(.fixup)