[PATCH 1/1] efi_loader: allow compiling with clang

[PATCH 1/1] efi_loader: allow compiling with clang

[Heinrich Schuchardt]

On ARM systems gd is stored in register r9 or x18. When compiling with
clang gd is defined as a macro calling function gd_ptr(). So we can not
make assignments to gd.

In the UEFI sub-system we need to save gd when leaving to UEFI binaries and
have to restore gd when reentering U-Boot.

Define a new function set_gd() for setting gd and use it in the UEFI
sub-system.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
---
 arch/arm/include/asm/global_data.h |  9 +++++++++
 lib/efi_loader/efi_boottime.c      | 10 +++++-----
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/arch/arm/include/asm/global_data.h b/arch/arm/include/asm/global_data.h
index f23b6bfb75..7c0905d240 100644
--- a/arch/arm/include/asm/global_data.h
+++ b/arch/arm/include/asm/global_data.h
@@ -117,4 +117,13 @@ static inline gd_t *get_gd(void)
 #endif
 #endif

+static inline void set_gd(volatile gd_t *gd_ptr)
+{
+#ifdef CONFIG_ARM64
+	__asm__ volatile("ldr x18, %0\n" : : "m"(gd_ptr));
+#else
+	__asm__ volatile("ldr r9, %0\n" : : "m"(gd_ptr));
+#endif
+}
+
 #endif /* __ASM_GBL_DATA_H */
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index db34938196..1591ad8300 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -49,7 +49,7 @@ static efi_handle_t current_image;
  * restriction so we need to manually swap its and our view of that register on
  * EFI callback entry/exit.
  */
-static volatile void *efi_gd, *app_gd;
+static volatile gd_t *efi_gd, *app_gd;
 #endif

 /* 1 if inside U-Boot code, 0 if inside EFI payload code */
@@ -89,7 +89,7 @@ int __efi_entry_check(void)
 #ifdef CONFIG_ARM
 	assert(efi_gd);
 	app_gd = gd;
-	gd = efi_gd;
+	set_gd(efi_gd);
 #endif
 	return ret;
 }
@@ -99,7 +99,7 @@ int __efi_exit_check(void)
 {
 	int ret = --entry_count == 0;
 #ifdef CONFIG_ARM
-	gd = app_gd;
+	set_gd(app_gd);
 #endif
 	return ret;
 }
@@ -123,7 +123,7 @@ void efi_restore_gd(void)
 	/* Only restore if we're already in EFI context */
 	if (!efi_gd)
 		return;
-	gd = efi_gd;
+	set_gd(efi_gd);
 #endif
 }

@@ -2920,7 +2920,7 @@ efi_status_t EFIAPI efi_start_image(efi_handle_t image_handle,
 		 * otherwise __efi_entry_check() will put the wrong value into
 		 * app_gd.
 		 */
-		gd = app_gd;
+		set_gd(app_gd);
 #endif
 		/*
 		 * To get ready to call EFI_EXIT below we have to execute the
--
2.26.2

[PATCH 1/1] efi_loader: allow compiling with clang

[Tom Rini]

On Wed, May 27, 2020 at 02:54:06AM +0200, Heinrich Schuchardt wrote:


> On ARM systems gd is stored in register r9 or x18. When compiling with
> clang gd is defined as a macro calling function gd_ptr(). So we can not
> make assignments to gd.
> 
> In the UEFI sub-system we need to save gd when leaving to UEFI binaries and
> have to restore gd when reentering U-Boot.
> 
> Define a new function set_gd() for setting gd and use it in the UEFI
> sub-system.
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

Tested-by: Tom Rini <trini@konsulko.com> [Raspberry Pi 3, 32bit, Clang 10]

-- 
Tom
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