[CI Check]ArmPkg: DefaultExceptionHandlerLib: Do Not Allocate Memory #4703
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If gST->ConOut is available when Arm's DefaultExceptionHandler is running, AsciiPrint will get called to attempt to print to ConOut, in addition to the serial output. AsciiPrint calls AsciiInternalPrint in UefiLibPrint.c which in turn calls AllocatePool to allocate a buffer to convert the Ascii input string to a Unicode string to pass to ConOut->OutputString. Per the comment on DefaultExceptionHandler, we should not be allocating memory in the exception handler, as this can cause the exception handler to fail if we had a memory exception or the system state is such that we cannot allocate memory. It has been observed on ArmVirtQemu that exceptions generated in the memory handling code will fail to output the stack dump and CPU state that is critical to debugging because the AllocatePool will fail. This patch fixes the Arm and AARCH64 DefaultExceptionHandlers to not allocate memory when ConOut is available and instead use stack memory to convert the Ascii string needed for SerialPortWrite to the Unicode string needed for ConOut->OutputString. Correspondingly, ArmVirtQemu can now output the stack dump and CPU state when hitting an exception in memory code. Cc: Leif Lindholm <quic_llindhol@quicinc.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Sami Mujawar <sami.mujawar@arm.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Oliver Smith-Denny <osde@linux.microsoft.com>
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Closing for v2. |
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Changes since v1: - Move OutputString write to after serial logging - Drop sending "Recursive Exception" to ConOut If gST->ConOut is available when Arm's DefaultExceptionHandler is running, AsciiPrint will get called to attempt to print to ConOut, in addition to the serial output. AsciiPrint calls AsciiInternalPrint in UefiLibPrint.c which in turn calls AllocatePool to allocate a buffer to convert the Ascii input string to a Unicode string to pass to ConOut->OutputString. Per the comment on DefaultExceptionHandler, we should not be allocating memory in the exception handler, as this can cause the exception handler to fail if we had a memory exception or the system state is such that we cannot allocate memory. It has been observed on ArmVirtQemu that exceptions generated in the memory handling code will fail to output the stack dump and CPU state that is critical to debugging because the AllocatePool will fail. This patch fixes the Arm and AARCH64 DefaultExceptionHandlers to not allocate memory when ConOut is available and instead use stack memory to convert the Ascii string needed for SerialPortWrite to the Unicode string needed for ConOut->OutputString. Correspondingly, ArmVirtQemu can now output the stack dump and CPU state when hitting an exception in memory code. GitHub PR: tianocore#4703 Cc: Leif Lindholm <quic_llindhol@quicinc.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Sami Mujawar <sami.mujawar@arm.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Oliver Smith-Denny <osde@linux.microsoft.com>
os-d
pushed a commit
to os-d/edk2
that referenced
this pull request
Aug 2, 2023
Changes since v1: - Move OutputString write to after serial logging - Drop sending "Recursive Exception" to ConOut If gST->ConOut is available when Arm's DefaultExceptionHandler is running, AsciiPrint will get called to attempt to print to ConOut, in addition to the serial output. AsciiPrint calls AsciiInternalPrint in UefiLibPrint.c which in turn calls AllocatePool to allocate a buffer to convert the Ascii input string to a Unicode string to pass to ConOut->OutputString. Per the comment on DefaultExceptionHandler, we should not be allocating memory in the exception handler, as this can cause the exception handler to fail if we had a memory exception or the system state is such that we cannot allocate memory. It has been observed on ArmVirtQemu that exceptions generated in the memory handling code will fail to output the stack dump and CPU state that is critical to debugging because the AllocatePool will fail. This patch fixes the Arm and AARCH64 DefaultExceptionHandlers to not allocate memory when ConOut is available and instead use stack memory to convert the Ascii string needed for SerialPortWrite to the Unicode string needed for ConOut->OutputString. Correspondingly, ArmVirtQemu can now output the stack dump and CPU state when hitting an exception in memory code. GitHub PR: tianocore#4703 Cc: Leif Lindholm <quic_llindhol@quicinc.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Sami Mujawar <sami.mujawar@arm.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Oliver Smith-Denny <osde@linux.microsoft.com>
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If gST->ConOut is available when Arm's DefaultExceptionHandler is running, AsciiPrint will get called to attempt to print to ConOut, in addition to the serial output.
AsciiPrint calls AsciiInternalPrint in UefiLibPrint.c which in turn calls AllocatePool to allocate a buffer to convert the Ascii input string to a Unicode string to pass to ConOut->OutputString.
Per the comment on DefaultExceptionHandler, we should not be allocating memory in the exception handler, as this can cause the exception handler to fail if we had a memory exception or the system state is such that we cannot allocate memory.
It has been observed on ArmVirtQemu that exceptions generated in the memory handling code will fail to output the stack dump and CPU state that is critical to debugging because the AllocatePool will fail.
This patch fixes the Arm and AARCH64 DefaultExceptionHandlers to not allocate memory when ConOut is available and instead use stack memory to convert the Ascii string needed for SerialPortWrite to the Unicode string needed for ConOut->OutputString. Correspondingly, ArmVirtQemu can now output the stack dump and CPU state when hitting an exception in memory code.
Cc: Leif Lindholm quic_llindhol@quicinc.com
Cc: Ard Biesheuvel ardb+tianocore@kernel.org
Cc: Sami Mujawar sami.mujawar@arm.com
Cc: Gerd Hoffmann kraxel@redhat.com