efi/libstub/arm64: avoid image_base value from efi_loaded_image

PATCH In review Ard Biesheuvel 4 participants 13 messages Mar 28, 2020 – Apr 7, 2020 EFI

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Ard Biesheuvel

author maintainer

2020-03-28 20:58 UTC #0 lore raw

PATCH 1/1 efi/libstub/arm64: avoid image_base value from efi_loaded_image

Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.

However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.

While at it, fix another issue in commit 9f9223778ef3, which may result in the unassigned image_addr to be misidentified as the preferred load offset of the kernel, which is unlikely but will cause a boot crash if it does occur.

Finally, let's add a warning if the _text vs. image_base discrepancy is detected, so we can tell more easily how widespread this issue actually is.

Reported-by Michael Kelley <[email protected]>

Signed-off-by Ard Biesheuvel <[email protected]>

---
 drivers/firmware/efi/libstub/arm64-stub.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

drivers/firmware/efi/libstub/arm64-stub.c +6 -1

index 9254cd8ab2d3..db0c1a9c1699 100644
@@ -116,6 +116,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 		 * Mustang), we can still place the kernel at the address
 		 * 'dram_base + TEXT_OFFSET'.
 		 */
+		*image_addr = (unsigned long)_text;
 		if (*image_addr == preferred_offset)
 			return EFI_SUCCESS;

@@ -140,7 +141,11 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 		}
 		*image_addr = *reserve_addr + TEXT_OFFSET;
 	}
-	memcpy((void *)*image_addr, image->image_base, kernel_size);
+
+	if (image->image_base != _text)
+		pr_efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n");
+
+	memcpy((void *)*image_addr, _text, kernel_size);
 
 	return EFI_SUCCESS;
 }

Signature · 1 line

2.17.1

Michael Kelley

Tested-by on v1 1/1

2020-03-28 23:55 UTC #1 lore raw

From: Ard Biesheuvel <[email protected]> Sent: Saturday, March 28, 2020 1:58 PM

Quoted 21 lines

Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.
However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.
While at it, fix another issue in commit 9f9223778ef3, which may result in the unassigned image_addr to be misidentified as the preferred load offset of the kernel, which is unlikely but will cause a boot crash if it does occur.
Finally, let's add a warning if the _text vs. image_base discrepancy is detected, so we can tell more easily how widespread this issue actually is.

Quoted 5 lines

Reported-by Michael Kelley <[email protected]>
Signed-off-by Ard Biesheuvel <[email protected]>
---
 drivers/firmware/efi/libstub/arm64-stub.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Tested in a Hyper-V VM. With the 2.02~beta2 version of grub, the FIRMWARE BUG message is output and then Linux correctly boots. With the 2.04-4 version of grub, Linux correctly boots with no error messages.

Tested-by Michael Kelley <[email protected]>

Quoted 30 lines

drivers/firmware/efi/libstub/arm64-stub.c +6 -1

index 9254cd8ab2d3..db0c1a9c1699 100644
@@ -116,6 +116,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 		 * Mustang), we can still place the kernel at the address
 		 * 'dram_base + TEXT_OFFSET'.
 		 */
+		*image_addr = (unsigned long)_text;
 		if (*image_addr == preferred_offset)
 			return EFI_SUCCESS;

@@ -140,7 +141,11 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 		}
 		*image_addr = *reserve_addr + TEXT_OFFSET;
 	}
-	memcpy((void *)*image_addr, image->image_base, kernel_size);
+
+	if (image->image_base != _text)
+		pr_efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus
 value\n");
+
+	memcpy((void *)*image_addr, _text, kernel_size);
 
 	return EFI_SUCCESS;

}
--
2.17.1

Leif Lindholm

2020-03-30 07:47 UTC #2 lore raw

In reply to Ard Biesheuvel

Quoted 10 lines · Ard Biesheuvel

Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.
However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.

It is not clear to me how "older GRUB builds" would differ here. I think more investigation is needed before making that claim. My suspicion is that some (old) version of non-upstream, shim-enabled distro-specific build is playing a part.

So, do we have the option for more detailed investigations, or can we vague the claim up to say "some GRUB builds seen in the wild, based on an upstream 2.02" or suchlike?

/
Leif

Quoted 43 lines

While at it, fix another issue in commit 9f9223778ef3, which may result in the unassigned image_addr to be misidentified as the preferred load offset of the kernel, which is unlikely but will cause a boot crash if it does occur.
Finally, let's add a warning if the _text vs. image_base discrepancy is detected, so we can tell more easily how widespread this issue actually is.
Reported-by Michael Kelley <[email protected]>
Signed-off-by Ard Biesheuvel <[email protected]>
---
 drivers/firmware/efi/libstub/arm64-stub.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
drivers/firmware/efi/libstub/arm64-stub.c +6 -1
index 9254cd8ab2d3..db0c1a9c1699 100644
@@ -116,6 +116,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 		 * Mustang), we can still place the kernel at the address
 		 * 'dram_base + TEXT_OFFSET'.
 		 */
+		*image_addr = (unsigned long)_text;
 		if (*image_addr == preferred_offset)
 			return EFI_SUCCESS;
 
@@ -140,7 +141,11 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 		}
 		*image_addr = *reserve_addr + TEXT_OFFSET;
 	}
-	memcpy((void *)*image_addr, image->image_base, kernel_size);
+
+	if (image->image_base != _text)
+		pr_efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n");
+
+	memcpy((void *)*image_addr, _text, kernel_size);
 
 	return EFI_SUCCESS;
 }
Signature · 1 line
2.17.1

Ard Biesheuvel

author maintainer

2020-03-30 07:50 UTC #3 lore raw

Quoted 13 lines · Leif Lindholm

Quoted 10 lines · Ard Biesheuvel
Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.
However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.

Quoted 9 lines

It is not clear to me how "older GRUB builds" would differ here. I think more investigation is needed before making that claim. My suspicion is that some (old) version of non-upstream, shim-enabled distro-specific build is playing a part.
So, do we have the option for more detailed investigations, or can we vague the claim up to say "some GRUB builds seen in the wild, based on an upstream 2.02" or suchlike?

I've queued a fix that prints a nastygram if the value deviates from the expected one. Let's see if this triggers any reports.

Ard Biesheuvel

author maintainer

2020-03-30 07:51 UTC #4 lore raw

Quoted 20 lines · Ard Biesheuvel

Quoted 18 lines · Leif Lindholm
Quoted 10 lines · Ard Biesheuvel
Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.
However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.
It is not clear to me how "older GRUB builds" would differ here. I think more investigation is needed before making that claim. My suspicion is that some (old) version of non-upstream, shim-enabled distro-specific build is playing a part.

Quoted 7 lines

Quoted 4 lines
So, do we have the option for more detailed investigations, or can we vague the claim up to say "some GRUB builds seen in the wild, based on an upstream 2.02" or suchlike?
I've queued a fix that prints a nastygram if the value deviates from the expected one. Let's see if this triggers any reports.

(/me looks at context)

*This* is the fix that prints a nastygram.

Michael Kelley

2020-03-30 18:12 UTC #5 lore raw

From: Ard Biesheuvel <[email protected]> Sent: Monday, March 30, 2020 12:51 AM

Quoted 27 lines · Ard Biesheuvel

Quoted 25 lines · Leif Lindholm
Quoted 22 lines · Ard Biesheuvel
Quoted 10 lines
Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.
However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.
It is not clear to me how "older GRUB builds" would differ here. I think more investigation is needed before making that claim. My suspicion is that some (old) version of non-upstream, shim-enabled distro-specific build is playing a part.
So, do we have the option for more detailed investigations, or can we vague the claim up to say "some GRUB builds seen in the wild, based on an upstream 2.02" or suchlike?

Quoted 6 lines

Quoted 2 lines
I've queued a fix that prints a nastygram if the value deviates from the expected one. Let's see if this triggers any reports.
(/me looks at context)
*This* is the fix that prints a nastygram.

FWIW, I pulled the BOOTAA64.EFI and grubaa64.efi files from CentOS 7.6 and CentOS 8.0 binary packages and tested both in my Hyper-V VM. Using strings | grep '2\.' to get version info, the CentOS 7.6 grubaa64.efi shows:

	User-Agent: GRUB 2.02~beta2

The CentOS 8.0 grubaa64.efi shows:

	User-Agent: GRUB 2.03

Both versions produce the FIRMWARE BUG warning when using Ard's latest patch. I'll assume the equivalent RHEL versions are the same. So we've got official distro releases that show the problem.

As reported earlier, the BOOTAA64.EFI and grubaa64.efi from a Debian release (not exactly sure which one) do not produce the FIRMWARE BUG warning. The grubaa64.efi reports as 2.04-4.

Michael
_______________________________________________
linux-arm-kernel mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Ard Biesheuvel

author maintainer

2020-03-30 18:24 UTC #6 lore raw

Quoted 47 lines · Michael Kelley

From: Ard Biesheuvel <[email protected]> Sent: Monday, March 30, 2020 12:51 AM
Quoted 27 lines · Ard Biesheuvel
Quoted 25 lines · Leif Lindholm
Quoted 22 lines · Ard Biesheuvel
Quoted 10 lines
Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.
However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.
It is not clear to me how "older GRUB builds" would differ here. I think more investigation is needed before making that claim. My suspicion is that some (old) version of non-upstream, shim-enabled distro-specific build is playing a part.
So, do we have the option for more detailed investigations, or can we vague the claim up to say "some GRUB builds seen in the wild, based on an upstream 2.02" or suchlike?
Quoted 6 lines
Quoted 2 lines
I've queued a fix that prints a nastygram if the value deviates from the expected one. Let's see if this triggers any reports.
(/me looks at context)
*This* is the fix that prints a nastygram.
FWIW, I pulled the BOOTAA64.EFI and grubaa64.efi files from CentOS 7.6 and CentOS 8.0 binary packages and tested both in my Hyper-V VM. Using strings | grep '2\.' to get version info, the CentOS 7.6 grubaa64.efi shows:
        User-Agent: GRUB 2.02~beta2
The CentOS 8.0 grubaa64.efi shows:
        User-Agent: GRUB 2.03

Quoted 8 lines

Both versions produce the FIRMWARE BUG warning when using Ard's latest patch. I'll assume the equivalent RHEL versions are the same. So we've got official distro releases that show the problem.
As reported earlier, the BOOTAA64.EFI and grubaa64.efi from a Debian release (not exactly sure which one) do not produce the FIRMWARE BUG warning. The grubaa64.efi reports as 2.04-4.

Thanks a lot Michael, that is really helpful.

Ard Biesheuvel

author maintainer

2020-03-31 07:56 UTC #7 lore raw

Quoted 53 lines · Ard Biesheuvel

Quoted 51 lines · Michael Kelley
From: Ard Biesheuvel <[email protected]> Sent: Monday, March 30, 2020 12:51 AM
Quoted 27 lines · Ard Biesheuvel
Quoted 25 lines · Leif Lindholm
Quoted 22 lines · Ard Biesheuvel
Quoted 10 lines
Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.
However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.
It is not clear to me how "older GRUB builds" would differ here. I think more investigation is needed before making that claim. My suspicion is that some (old) version of non-upstream, shim-enabled distro-specific build is playing a part.
So, do we have the option for more detailed investigations, or can we vague the claim up to say "some GRUB builds seen in the wild, based on an upstream 2.02" or suchlike?
Quoted 6 lines
Quoted 2 lines
I've queued a fix that prints a nastygram if the value deviates from the expected one. Let's see if this triggers any reports.
(/me looks at context)
*This* is the fix that prints a nastygram.
FWIW, I pulled the BOOTAA64.EFI and grubaa64.efi files from CentOS 7.6 and CentOS 8.0 binary packages and tested both in my Hyper-V VM. Using strings | grep '2\.' to get version info, the CentOS 7.6 grubaa64.efi shows:
        User-Agent: GRUB 2.02~beta2
The CentOS 8.0 grubaa64.efi shows:
        User-Agent: GRUB 2.03
Both versions produce the FIRMWARE BUG warning when using Ard's latest patch. I'll assume the equivalent RHEL versions are the same. So we've got official distro releases that show the problem.

Quoted 6 lines

Quoted 4 lines
As reported earlier, the BOOTAA64.EFI and grubaa64.efi from a Debian release (not exactly sure which one) do not produce the FIRMWARE BUG warning. The grubaa64.efi reports as 2.04-4.
Thanks a lot Michael, that is really helpful.

I could not reproduce the issue with Debian Stretch's 2.02~beta3-5+deb9u2, so it does appear to be RedHat's value add that is to blame here.

@Laszlo: TL;DR RedHat's GRUB for arm64 appears to clobber the image_base field of the efi_loaded_image struct passed to the kernel. Could you please recommend a way to report this?

Michael Kelley

2020-03-31 13:37 UTC #8 lore raw

From: Ard Biesheuvel <[email protected]> Sent: Tuesday, March 31, 2020 12:56 AM

Quoted 62 lines · Ard Biesheuvel

Quoted 53 lines · Michael Kelley
Quoted 51 lines
From: Ard Biesheuvel <[email protected]> Sent: Monday, March 30, 2020 12:51 AM
Quoted 27 lines · Ard Biesheuvel
Quoted 25 lines · Leif Lindholm
Quoted 22 lines · Ard Biesheuvel
Quoted 10 lines
Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.
However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.
It is not clear to me how "older GRUB builds" would differ here. I think more investigation is needed before making that claim. My suspicion is that some (old) version of non-upstream, shim-enabled distro-specific build is playing a part.
So, do we have the option for more detailed investigations, or can we vague the claim up to say "some GRUB builds seen in the wild, based on an upstream 2.02" or suchlike?
Quoted 6 lines
Quoted 2 lines
I've queued a fix that prints a nastygram if the value deviates from the expected one. Let's see if this triggers any reports.
(/me looks at context)
*This* is the fix that prints a nastygram.
FWIW, I pulled the BOOTAA64.EFI and grubaa64.efi files from CentOS 7.6 and CentOS 8.0 binary packages and tested both in my Hyper-V VM. Using strings | grep '2\.' to get version info, the CentOS 7.6 grubaa64.efi shows:
        User-Agent: GRUB 2.02~beta2
The CentOS 8.0 grubaa64.efi shows:
        User-Agent: GRUB 2.03
Both versions produce the FIRMWARE BUG warning when using Ard's latest patch. I'll assume the equivalent RHEL versions are the same. So we've got official distro releases that show the problem.
Quoted 6 lines
Quoted 4 lines
As reported earlier, the BOOTAA64.EFI and grubaa64.efi from a Debian release (not exactly sure which one) do not produce the FIRMWARE BUG warning. The grubaa64.efi reports as 2.04-4.
Thanks a lot Michael, that is really helpful.

Quoted 7 lines

I could not reproduce the issue with Debian Stretch's 2.02~beta3-5+deb9u2, so it does appear to be RedHat's value add that is to blame here.
@Laszlo: TL;DR RedHat's GRUB for arm64 appears to clobber the image_base field of the efi_loaded_image struct passed to the kernel. Could you please recommend a way to report this?

Or there could be something weird about my Hyper-V VM. I have a couple of ARM64 bare metal machines, but they are in the office with no remote access, and we're on the work-from-home plan for now. But I may be able to get into the office later this week and try it. I'd like to rule out anything related to Hyper-V, and will update this thread if I can.

Michael

Michael Kelley

2020-04-06 17:13 UTC #9 lore raw

From: Michael Kelley Sent: Tuesday, March 31, 2020 6:38 AM

Quoted 72 lines

From: Ard Biesheuvel <[email protected]> Sent: Tuesday, March 31, 2020 12:56 AM
Quoted 62 lines · Ard Biesheuvel
Quoted 53 lines · Michael Kelley
Quoted 51 lines
From: Ard Biesheuvel <[email protected]> Sent: Monday, March 30, 2020 12:51 AM
Quoted 27 lines · Ard Biesheuvel
Quoted 25 lines · Leif Lindholm
Quoted 22 lines · Ard Biesheuvel
Quoted 10 lines
Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.
However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.
It is not clear to me how "older GRUB builds" would differ here. I think more investigation is needed before making that claim. My suspicion is that some (old) version of non-upstream, shim-enabled distro-specific build is playing a part.
So, do we have the option for more detailed investigations, or can we vague the claim up to say "some GRUB builds seen in the wild, based on an upstream 2.02" or suchlike?
Quoted 6 lines
Quoted 2 lines
I've queued a fix that prints a nastygram if the value deviates from the expected one. Let's see if this triggers any reports.
(/me looks at context)
*This* is the fix that prints a nastygram.
FWIW, I pulled the BOOTAA64.EFI and grubaa64.efi files from CentOS 7.6 and CentOS 8.0 binary packages and tested both in my Hyper-V VM. Using strings | grep '2\.' to get version info, the CentOS 7.6 grubaa64.efi shows:
        User-Agent: GRUB 2.02~beta2
The CentOS 8.0 grubaa64.efi shows:
        User-Agent: GRUB 2.03
Both versions produce the FIRMWARE BUG warning when using Ard's latest patch. I'll assume the equivalent RHEL versions are the same. So we've got official distro releases that show the problem.
Quoted 6 lines
Quoted 4 lines
As reported earlier, the BOOTAA64.EFI and grubaa64.efi from a Debian release (not exactly sure which one) do not produce the FIRMWARE BUG warning. The grubaa64.efi reports as 2.04-4.
Thanks a lot Michael, that is really helpful.
Quoted 7 lines
I could not reproduce the issue with Debian Stretch's 2.02~beta3-5+deb9u2, so it does appear to be RedHat's value add that is to blame here.
@Laszlo: TL;DR RedHat's GRUB for arm64 appears to clobber the image_base field of the efi_loaded_image struct passed to the kernel. Could you please recommend a way to report this?

Quoted 7 lines

Or there could be something weird about my Hyper-V VM. I have a couple of ARM64 bare metal machines, but they are in the office with no remote access, and we're on the work-from-home plan for now. But I may be able to get into the office later this week and try it. I'd like to rule out anything related to Hyper-V, and will update this thread if I can.

I have tried this scenario on bare metal running RHEL 7.4, and the problem reproduces as described above. So this is *not* related to running in a Hyper-V VM, which is what I wanted to make sure of.

Michael

Ard Biesheuvel

author maintainer

2020-04-07 08:08 UTC #10 lore raw

Quoted 82 lines · Michael Kelley

From: Michael Kelley Sent: Tuesday, March 31, 2020 6:38 AM
Quoted 72 lines
From: Ard Biesheuvel <[email protected]> Sent: Tuesday, March 31, 2020 12:56 AM
Quoted 62 lines · Ard Biesheuvel
Quoted 53 lines · Michael Kelley
Quoted 51 lines
From: Ard Biesheuvel <[email protected]> Sent: Monday, March 30, 2020 12:51 AM
Quoted 27 lines · Ard Biesheuvel
Quoted 25 lines · Leif Lindholm
Quoted 22 lines · Ard Biesheuvel
Quoted 10 lines
Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.
However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.
It is not clear to me how "older GRUB builds" would differ here. I think more investigation is needed before making that claim. My suspicion is that some (old) version of non-upstream, shim-enabled distro-specific build is playing a part.
So, do we have the option for more detailed investigations, or can we vague the claim up to say "some GRUB builds seen in the wild, based on an upstream 2.02" or suchlike?
Quoted 6 lines
Quoted 2 lines
I've queued a fix that prints a nastygram if the value deviates from the expected one. Let's see if this triggers any reports.
(/me looks at context)
*This* is the fix that prints a nastygram.
FWIW, I pulled the BOOTAA64.EFI and grubaa64.efi files from CentOS 7.6 and CentOS 8.0 binary packages and tested both in my Hyper-V VM. Using strings | grep '2\.' to get version info, the CentOS 7.6 grubaa64.efi shows:
        User-Agent: GRUB 2.02~beta2
The CentOS 8.0 grubaa64.efi shows:
        User-Agent: GRUB 2.03
Both versions produce the FIRMWARE BUG warning when using Ard's latest patch. I'll assume the equivalent RHEL versions are the same. So we've got official distro releases that show the problem.
Quoted 6 lines
Quoted 4 lines
As reported earlier, the BOOTAA64.EFI and grubaa64.efi from a Debian release (not exactly sure which one) do not produce the FIRMWARE BUG warning. The grubaa64.efi reports as 2.04-4.
Thanks a lot Michael, that is really helpful.
Quoted 7 lines
I could not reproduce the issue with Debian Stretch's 2.02~beta3-5+deb9u2, so it does appear to be RedHat's value add that is to blame here.
@Laszlo: TL;DR RedHat's GRUB for arm64 appears to clobber the image_base field of the efi_loaded_image struct passed to the kernel. Could you please recommend a way to report this?
Quoted 7 lines
Or there could be something weird about my Hyper-V VM. I have a couple of ARM64 bare metal machines, but they are in the office with no remote access, and we're on the work-from-home plan for now. But I may be able to get into the office later this week and try it. I'd like to rule out anything related to Hyper-V, and will update this thread if I can.

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I have tried this scenario on bare metal running RHEL 7.4, and the problem reproduces as described above. So this is *not* related to running in a Hyper-V VM, which is what I wanted to make sure of.

Thanks Michael. I'll mention this in the bugzilla entry.

Laszlo Ersek

2020-03-31 19:20 UTC #11 lore raw

In reply to Ard Biesheuvel

Quoted 61 lines · Ard Biesheuvel

Quoted 53 lines · Ard Biesheuvel
Quoted 51 lines · Michael Kelley
From: Ard Biesheuvel <[email protected]> Sent: Monday, March 30, 2020 12:51 AM
Quoted 27 lines · Ard Biesheuvel
Quoted 25 lines · Leif Lindholm
Quoted 22 lines · Ard Biesheuvel
Quoted 10 lines
Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.
However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.
It is not clear to me how "older GRUB builds" would differ here. I think more investigation is needed before making that claim. My suspicion is that some (old) version of non-upstream, shim-enabled distro-specific build is playing a part.
So, do we have the option for more detailed investigations, or can we vague the claim up to say "some GRUB builds seen in the wild, based on an upstream 2.02" or suchlike?
Quoted 6 lines
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I've queued a fix that prints a nastygram if the value deviates from the expected one. Let's see if this triggers any reports.
(/me looks at context)
*This* is the fix that prints a nastygram.
FWIW, I pulled the BOOTAA64.EFI and grubaa64.efi files from CentOS 7.6 and CentOS 8.0 binary packages and tested both in my Hyper-V VM. Using strings | grep '2\.' to get version info, the CentOS 7.6 grubaa64.efi shows:
        User-Agent: GRUB 2.02~beta2
The CentOS 8.0 grubaa64.efi shows:
        User-Agent: GRUB 2.03
Both versions produce the FIRMWARE BUG warning when using Ard's latest patch. I'll assume the equivalent RHEL versions are the same. So we've got official distro releases that show the problem.
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As reported earlier, the BOOTAA64.EFI and grubaa64.efi from a Debian release (not exactly sure which one) do not produce the FIRMWARE BUG warning. The grubaa64.efi reports as 2.04-4.
Thanks a lot Michael, that is really helpful.

Quoted 7 lines

I could not reproduce the issue with Debian Stretch's 2.02~beta3-5+deb9u2, so it does appear to be RedHat's value add that is to blame here.
@Laszlo: TL;DR RedHat's GRUB for arm64 appears to clobber the image_base field of the efi_loaded_image struct passed to the kernel. Could you please recommend a way to report this?

Yes. I seem to recall that you already have an account at
<https://bugzilla.redhat.com/>. Please log in, then go to the following link:

https://bugzilla.redhat.com/enter_bug.cgi?product=Red%20Hat%20Enterprise%20Linux%208

In the "Component" field, please enter "grub2", then fill in Summary / Description / etc.

Please be thorough, as if you wanted me to reproduce the issue :)

After filing the bug, please send the BZ link to me (or add me to the bug's CC list), so I can ping some RH bootloader folks directly.

Thanks!
Laszlo

Ard Biesheuvel

author maintainer

2020-04-01 08:24 UTC #12 lore raw

Quoted 77 lines · Laszlo Ersek

Quoted 61 lines · Ard Biesheuvel
Quoted 53 lines · Ard Biesheuvel
Quoted 51 lines · Michael Kelley
From: Ard Biesheuvel <[email protected]> Sent: Monday, March 30, 2020 12:51 AM
Quoted 27 lines · Ard Biesheuvel
Quoted 25 lines · Leif Lindholm
Quoted 22 lines · Ard Biesheuvel
Quoted 10 lines
Commit 9f9223778ef3 ("efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint") did some code refactoring to get rid of the EFI entry point assembler code, and in the process, it got rid of the assignment of image_addr to the value of _text. Instead, it switched to using the image_base field of the efi_loaded_image struct provided by UEFI, which should contain the same value.
However, Michael reports that this is not the case: older GRUB builds corrupt this value in some way, and since we can easily switch back to referring to _text to discover this value, let's simply do that.
It is not clear to me how "older GRUB builds" would differ here. I think more investigation is needed before making that claim. My suspicion is that some (old) version of non-upstream, shim-enabled distro-specific build is playing a part.
So, do we have the option for more detailed investigations, or can we vague the claim up to say "some GRUB builds seen in the wild, based on an upstream 2.02" or suchlike?
Quoted 6 lines
Quoted 2 lines
I've queued a fix that prints a nastygram if the value deviates from the expected one. Let's see if this triggers any reports.
(/me looks at context)
*This* is the fix that prints a nastygram.
FWIW, I pulled the BOOTAA64.EFI and grubaa64.efi files from CentOS 7.6 and CentOS 8.0 binary packages and tested both in my Hyper-V VM. Using strings | grep '2\.' to get version info, the CentOS 7.6 grubaa64.efi shows:
        User-Agent: GRUB 2.02~beta2
The CentOS 8.0 grubaa64.efi shows:
        User-Agent: GRUB 2.03
Both versions produce the FIRMWARE BUG warning when using Ard's latest patch. I'll assume the equivalent RHEL versions are the same. So we've got official distro releases that show the problem.
Quoted 6 lines
Quoted 4 lines
As reported earlier, the BOOTAA64.EFI and grubaa64.efi from a Debian release (not exactly sure which one) do not produce the FIRMWARE BUG warning. The grubaa64.efi reports as 2.04-4.
Thanks a lot Michael, that is really helpful.
Quoted 7 lines
I could not reproduce the issue with Debian Stretch's 2.02~beta3-5+deb9u2, so it does appear to be RedHat's value add that is to blame here.
@Laszlo: TL;DR RedHat's GRUB for arm64 appears to clobber the image_base field of the efi_loaded_image struct passed to the kernel. Could you please recommend a way to report this?
Yes. I seem to recall that you already have an account at
<https://bugzilla.redhat.com/>. Please log in, then go to the following link:
https://bugzilla.redhat.com/enter_bug.cgi?product=Red%20Hat%20Enterprise%20Linux%208

Quoted 8 lines

In the "Component" field, please enter "grub2", then fill in Summary / Description / etc.
Please be thorough, as if you wanted me to reproduce the issue :)
After filing the bug, please send the BZ link to me (or add me to the bug's CC list), so I can ping some RH bootloader folks directly.

https://bugzilla.redhat.com/show_bug.cgi?id=1819624

Thanks.