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x86: Handle 64bit framebuffer memory address properly

PATCH Superseded Kairui Song 3 participants 5 messages Nov 23, 2018 – May 31, 2019

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Live update kexec handover (KHO)

v1 of 2 Superseded Latest is v2 →

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Kairui Song

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#0 lore raw

PATCH 1/1 x86: Handle 64bit framebuffer memory address properly

In a EFI system, the frame buffer address is 64bit, so currently if the address is beyound 4G, kexec will set wrong address due to truncate.

Linux kernel commit ae2ee627dc87 ('efifb: Add support for 64-bit frame buffer addresses') added support for 64bit frame buffer address, an 'ext_lfb_base' field is added as the upper 32-bits of the frame buffer, and introduced a new capability flag 'VIDEO_TYPE_CAPABILITY_64BIT_BASE' to indicate if the extend field is used.

This patch adopts this change, set proper extent address and capability flag when the address is beyound 4G.

Signed-off-by Kairui Song <[email protected]>
---
 include/x86/x86-linux.h           | 7 +++++--
 kexec/arch/i386/x86-linux-setup.c | 7 ++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)
include/x86/x86-linux.h +5 -2
index 7834751..352ea02 100644
@@ -107,7 +107,10 @@ struct x86_linux_param_header {
 	uint16_t vesapm_seg;			/* 0x2e */
 	uint16_t vesapm_off;			/* 0x30 */
 	uint16_t pages;				/* 0x32 */
-	uint8_t  reserved4[12];			/* 0x34 -- 0x3f reserved for future expansion */
+	uint16_t vesa_attributes;		/* 0x34 */
+	uint32_t capabilities;			/* 0x36 */
+	uint32_t ext_lfb_base;			/* 0x3a */
+	uint8_t  reserved4[2];			/* 0x3e -- 0x3f reserved for future expansion */
 
 	struct apm_bios_info apm_bios_info;	/* 0x40 */
 	struct drive_info_struct drive_info;	/* 0x80 */

@@ -199,7 +202,7 @@ struct x86_linux_param_header {
 	struct 	edd_info eddbuf[EDDMAXNR];	/* 0xd00 */
 						/* 0xeec */
 #define COMMAND_LINE_SIZE 2048
-};
+} __attribute__((packed));
 
 struct x86_linux_faked_param_header {
 	struct x86_linux_param_header hdr;	/* 0x00 */
kexec/arch/i386/x86-linux-setup.c +6 -1
index 6cda12c..dc785a2 100644
@@ -158,10 +158,15 @@ static int setup_linux_vesafb(struct x86_linux_param_header *real_mode)
 	real_mode->lfb_width      = var.xres;
 	real_mode->lfb_height     = var.yres;
 	real_mode->lfb_depth      = var.bits_per_pixel;
-	real_mode->lfb_base       = fix.smem_start;
+	real_mode->lfb_base       = fix.smem_start & 0xffffffff;
 	real_mode->lfb_linelength = fix.line_length;
 	real_mode->vesapm_seg     = 0;
 
+	if (fix.smem_start > 0xffffffff) {
+		real_mode->ext_lfb_base = fix.smem_start >> 32;
+		real_mode->capabilities |= VIDEO_CAPABILITY_64BIT_BASE;
+	}
+
 	/* FIXME: better get size from the file returned by proc_iomem() */
 	real_mode->lfb_size       = (fix.smem_len + 65535) / 65536;
 	real_mode->pages          = (fix.smem_len + 4095) / 4096;
Signature · 7 lines
2.19.1


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#1 lore raw

Hi Kairui,

Quoted 50 lines · Kairui Song

In a EFI system, the frame buffer address is 64bit, so currently if the address is beyound 4G, kexec will set wrong address due to truncate.

Linux kernel commit ae2ee627dc87 ('efifb: Add support for 64-bit frame buffer addresses') added support for 64bit frame buffer address, an 'ext_lfb_base' field is added as the upper 32-bits of the frame buffer, and introduced a new capability flag 'VIDEO_TYPE_CAPABILITY_64BIT_BASE' to indicate if the extend field is used.

This patch adopts this change, set proper extent address and capability flag when the address is beyound 4G.

Signed-off-by Kairui Song <[email protected]>
---
 include/x86/x86-linux.h           | 7 +++++--
 kexec/arch/i386/x86-linux-setup.c | 7 ++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)
include/x86/x86-linux.h +5 -2
index 7834751..352ea02 100644
@@ -107,7 +107,10 @@ struct x86_linux_param_header {
 	uint16_t vesapm_seg;			/* 0x2e */
 	uint16_t vesapm_off;			/* 0x30 */
 	uint16_t pages;				/* 0x32 */
-	uint8_t  reserved4[12];			/* 0x34 -- 0x3f reserved for future expansion */
+	uint16_t vesa_attributes;		/* 0x34 */
+	uint32_t capabilities;			/* 0x36 */
+	uint32_t ext_lfb_base;			/* 0x3a */
+	uint8_t  reserved4[2];			/* 0x3e -- 0x3f reserved for future expansion */
 
 	struct apm_bios_info apm_bios_info;	/* 0x40 */
 	struct drive_info_struct drive_info;	/* 0x80 */

@@ -199,7 +202,7 @@ struct x86_linux_param_header {
 	struct 	edd_info eddbuf[EDDMAXNR];	/* 0xd00 */
 						/* 0xeec */
 #define COMMAND_LINE_SIZE 2048
-};
+} __attribute__((packed));
 
 struct x86_linux_faked_param_header {
 	struct x86_linux_param_header hdr;	/* 0x00 */
kexec/arch/i386/x86-linux-setup.c +0 -0
index 6cda12c..dc785a2 100644

kexec/arch/i386/x86-linux-setup.c static int setup_linux_vesafb(struct x86_linux_param_header *real_mode) · line 165

Quoted 9 lines
kexec/arch/i386/x86-linux-setup.c +2 -1
@@ -158,10 +158,15 @@ static int setup_linux_vesafb(struct x86_linux_param_header *real_mode)
 	real_mode->lfb_width      = var.xres;
 	real_mode->lfb_height     = var.yres;
 	real_mode->lfb_depth      = var.bits_per_pixel;
-	real_mode->lfb_base       = fix.smem_start;
+	real_mode->lfb_base       = fix.smem_start & 0xffffffff;
 	real_mode->lfb_linelength = fix.line_length;
 	real_mode->vesapm_seg     = 0;
 
+	if (fix.smem_start > 0xffffffff) {

This might be a problem for 32 bit case? Other than this I do not see other issues of this patch.

Quoted 15 lines
kexec/arch/i386/x86-linux-setup.c +4 -0
+		real_mode->ext_lfb_base = fix.smem_start >> 32;
+		real_mode->capabilities |= VIDEO_CAPABILITY_64BIT_BASE;
+	}
+
 	/* FIXME: better get size from the file returned by proc_iomem() */
 	real_mode->lfb_size       = (fix.smem_len + 65535) / 65536;
 	real_mode->pages          = (fix.smem_len + 4095) / 4096;
Signature · 7 lines
2.19.1


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Thanks
Dave

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author
#2 lore raw

Hi Dave, thanks for the review.
It should be safe, "smem_start" is defined as an unsigned long and with 32bit it will always smaller than 0xffffffff, but to make it cleaner and safer I will update the
patch to use 0xffffffffUL instead.

Quoted 85 lines · Dave Young

Hi Kairui,

Quoted 50 lines · Kairui Song

In a EFI system, the frame buffer address is 64bit, so currently if the address is beyound 4G, kexec will set wrong address due to truncate.

Linux kernel commit ae2ee627dc87 ('efifb: Add support for 64-bit frame buffer addresses') added support for 64bit frame buffer address, an 'ext_lfb_base' field is added as the upper 32-bits of the frame buffer, and introduced a new capability flag 'VIDEO_TYPE_CAPABILITY_64BIT_BASE' to indicate if the extend field is used.

This patch adopts this change, set proper extent address and capability flag when the address is beyound 4G.

Signed-off-by Kairui Song <[email protected]>
---
 include/x86/x86-linux.h           | 7 +++++--
 kexec/arch/i386/x86-linux-setup.c | 7 ++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)
include/x86/x86-linux.h +5 -2
index 7834751..352ea02 100644
@@ -107,7 +107,10 @@ struct x86_linux_param_header {
      uint16_t vesapm_seg;                    /* 0x2e */
      uint16_t vesapm_off;                    /* 0x30 */
      uint16_t pages;                         /* 0x32 */
-     uint8_t  reserved4[12];                 /* 0x34 -- 0x3f reserved for future expansion */
+     uint16_t vesa_attributes;               /* 0x34 */
+     uint32_t capabilities;                  /* 0x36 */
+     uint32_t ext_lfb_base;                  /* 0x3a */
+     uint8_t  reserved4[2];                  /* 0x3e -- 0x3f reserved for future expansion */
 
      struct apm_bios_info apm_bios_info;     /* 0x40 */
      struct drive_info_struct drive_info;    /* 0x80 */

@@ -199,7 +202,7 @@ struct x86_linux_param_header {
      struct  edd_info eddbuf[EDDMAXNR];      /* 0xd00 */
                                              /* 0xeec */
 #define COMMAND_LINE_SIZE 2048
-};
+} __attribute__((packed));
 
 struct x86_linux_faked_param_header {
      struct x86_linux_param_header hdr;      /* 0x00 */
kexec/arch/i386/x86-linux-setup.c +0 -0
index 6cda12c..dc785a2 100644

kexec/arch/i386/x86-linux-setup.c static int setup_linux_vesafb(struct x86_linux_param_header *real_mode) · line 165

Quoted 9 lines
kexec/arch/i386/x86-linux-setup.c +2 -1
@@ -158,10 +158,15 @@ static int setup_linux_vesafb(struct x86_linux_param_header *real_mode)
      real_mode->lfb_width      = var.xres;
      real_mode->lfb_height     = var.yres;
      real_mode->lfb_depth      = var.bits_per_pixel;
-     real_mode->lfb_base       = fix.smem_start;
+     real_mode->lfb_base       = fix.smem_start & 0xffffffff;
      real_mode->lfb_linelength = fix.line_length;
      real_mode->vesapm_seg     = 0;
 
+     if (fix.smem_start > 0xffffffff) {

This might be a problem for 32 bit case? Other than this I do not see other issues of this patch.

Quoted 11 lines
kexec/arch/i386/x86-linux-setup.c +4 -1
+             real_mode->ext_lfb_base = fix.smem_start >> 32;
+             real_mode->capabilities |= VIDEO_CAPABILITY_64BIT_BASE;
+     }
+
      /* FIXME: better get size from the file returned by proc_iomem() */
      real_mode->lfb_size       = (fix.smem_len + 65535) / 65536;
      real_mode->pages          = (fix.smem_len + 4095) / 4096;
--

2.19.1

Quoted 4 lines

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Thanks
Dave

Signature · 7 lines
Best Regards,
Kairui Song

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#3 lore raw
In reply to Kairui Song
Quoted 11 lines · Kairui Song

In a EFI system, the frame buffer address is 64bit, so currently if the address is beyound 4G, kexec will set wrong address due to truncate.

Linux kernel commit ae2ee627dc87 ('efifb: Add support for 64-bit frame buffer addresses') added support for 64bit frame buffer address, an 'ext_lfb_base' field is added as the upper 32-bits of the frame buffer, and introduced a new capability flag 'VIDEO_TYPE_CAPABILITY_64BIT_BASE' to indicate if the extend field is used.

Quoted 4 lines

This patch adopts this change, set proper extent address and capability flag when the address is beyound 4G.

Signed-off-by Kairui Song <[email protected]>

Sorry for letting this slip through the cracks.
Please let me know if this is still relevant.

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author
#4 lore raw
Quoted 13 lines · Simon Horman
Quoted 11 lines · Kairui Song

In a EFI system, the frame buffer address is 64bit, so currently if the address is beyound 4G, kexec will set wrong address due to truncate.

Linux kernel commit ae2ee627dc87 ('efifb: Add support for 64-bit frame buffer addresses') added support for 64bit frame buffer address, an 'ext_lfb_base' field is added as the upper 32-bits of the frame buffer, and introduced a new capability flag 'VIDEO_TYPE_CAPABILITY_64BIT_BASE' to indicate if the extend field is used.

Quoted 7 lines
Quoted 4 lines

This patch adopts this change, set proper extent address and capability flag when the address is beyound 4G.

Signed-off-by Kairui Song <[email protected]>

Sorry for letting this slip through the cracks.
Please let me know if this is still relevant.

Hi Simon, I checked kexec-tools repo and this patch is merged already, maybe you replied the wrong mail?

--
Best Regards,
Kairui Song

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