On 26.07.17 15:55, Rob Clark wrote:
Missing an EFI_ENTRY() or doubling up EFI_EXIT() leads to non-obvious
crashes. Let's add some error checking.
Signed-off-by: Rob Clark <robdcl...@gmail.com>
---
include/efi_loader.h | 5 +++++
lib/efi_loader/efi_boottime.c | 13 +++++++++++++
2 files changed, 18 insertions(+)
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 09bab7dbc6..4b49fac84b 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -15,11 +15,13 @@
#include <linux/list.h>
+int __efi_check_nesting(int delta);
/*
* Enter the u-boot world from UEFI:
*/
#define EFI_ENTRY(format, ...) do { \
efi_restore_gd(); \
+ assert(__efi_check_nesting(+1)); \
debug("EFI: Entry %s(" format ")\n", __func__, ##__VA_ARGS__); \
} while(0)
@@ -28,6 +30,7 @@
*/
#define EFI_EXIT(ret) ({ \
debug("EFI: Exit: %s: %u\n", __func__, (u32)((ret) & ~EFI_ERROR_MASK));
\
+ assert(__efi_check_nesting(-1)); \
efi_exit_func(ret); \
})
@@ -36,10 +39,12 @@
*/
#define EFI_CALL(exp) do { \
debug("EFI: Call: %s\n", #exp); \
+ assert(__efi_check_nesting(-1)); \
efi_exit_func(EFI_SUCCESS); \
exp; \
efi_restore_gd(); \
debug("EFI: Return From: %s\n", #exp); \
+ assert(__efi_check_nesting(+1)); \
} while(0)
extern struct efi_runtime_services efi_runtime_services;
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index 76cafffc1d..b21df7bd5d 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -57,6 +57,17 @@ void efi_save_gd(void)
#endif
}
+/* Check for incorrect use of EFI_ENTRY() / EFI_EXIT() */
+int __efi_check_nesting(int delta)
+{
+ static int entry_count;
I'd prefer if we marked globals as such (read: somewhere at the top of a
.c file).
Also I think this function would be better off as a static inline in a
header, as it should get compressed quite well.
+ /* post-increment, pre-decrement: */
+ if (delta > 0)
+ return entry_count++ == 0;
+ else
+ return --entry_count == 0;
I have a hard time to wrap my head around the logic. At least, couldn't
you split this into 2 functions? :)
Alex
+}
+
/* Called on every callback entry */
void efi_restore_gd(void)
{
@@ -716,7 +727,9 @@ static efi_status_t EFIAPI efi_start_image(efi_handle_t
image_handle,
return EFI_EXIT(info->exit_status);
}
+ __efi_check_nesting(-1);
entry(image_handle, &systab);
+ __efi_check_nesting(+1);
/* Should usually never get here */
return EFI_EXIT(EFI_SUCCESS);
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