On Wed, Jul 26, 2017 at 4:12 PM, Alexander Graf agraf@suse.de wrote:
On 26.07.17 18:41, Rob Clark wrote:
On Wed, Jul 26, 2017 at 11:25 AM, Alexander Graf agraf@suse.de wrote:
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 robdclark@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); \ })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)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).
hmm, well that does increase the scope unnecessarily, which is why I made it static inside the fxn. But if you can prefer I guess I can put it just above __efi_check_nesting().
It's a matter of taste, but in general I find it very useful to know at a glimpse where .bss, .rodata and .data come from.
Also I think this function would be better off as a static inline in a header, as it should get compressed quite well.
That would mean making entry_count also non-static (ie. broader than
Ah, no, entry_count would still be in efi_boottime.c, but the function using it would be in a .h file. That way we don't need to do the register save/restore dance we need to do for full remote function calls.
Ok.. I'm thinking about just moving these calls into efi_restore_gd()/efi_exit_func() but leaving the asserts in the macro (so the assert reflects the proper file/line). Minor downside is the assert would come before the debug() print, but since it has file/line I guess that isn't really important.
Fortunately the one place we need to special-case call the check_nesting() (ie. efi_start_image()) is in the same object file.
I'll give that a go this evening and see how it turns out.
BR, -R