| Message ID | 1404468997-6925-1-git-send-email-ard.biesheuvel@linaro.org |
|---|---|
| State | New |
| Headers | show |
On Fri, 2014-07-04 at 12:16 +0200, Ard Biesheuvel wrote: > If we cannot resolve the virtual address of the UEFI System Table, its physical > offset must be missing from the virtual memory map, and there is really no point > in proceeding with installing the virtual memory map and the runtime services > dispatch table. So back out gracefully. > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > --- > > v2: > - release mappings and free virtmap before bailing > > arch/arm64/kernel/efi.c | 28 ++++++++++++++++++++++++++-- > 1 file changed, 26 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c > index 56c3327bbf79..23942158e0f8 100644 > --- a/arch/arm64/kernel/efi.c > +++ b/arch/arm64/kernel/efi.c > @@ -416,11 +416,23 @@ static int __init arm64_enter_virtual_mode(void) > continue; > if (remap_region(md, &virt_md)) > ++count; > + else > + goto err_unmap; How about: if (!remap_region(md, &virt_md)) goto err_unmap; ++count; > } > > efi.systab = (__force void *)efi_lookup_mapped_addr(efi_system_table); > - if (efi.systab) > - set_bit(EFI_SYSTEM_TABLES, &efi.flags); > + if (!efi.systab) { > + /* > + * If we have no virtual mapping for the System Table at this > + * point, the memory map doesn't cover the physical offset where > + * it resides. This means the System Table will be inaccessible > + * to Runtime Services themselves once the virtual mapping is > + * installed. > + */ > + pr_err("Failed to remap EFI System Table -- buggy firmware?\n"); > + goto err_unmap; > + } > + set_bit(EFI_SYSTEM_TABLES, &efi.flags); > > local_irq_save(flags); > cpu_switch_mm(idmap_pg_dir, &init_mm); > @@ -453,5 +465,17 @@ static int __init arm64_enter_virtual_mode(void) > set_bit(EFI_RUNTIME_SERVICES, &efi.flags); > > return 0; > + > +err_unmap: > + /* unmap all mappings that succeeded: there are 'count' of those */ > + for_each_efi_memory_desc(&memmap, md) { > + if (!(md->attribute & EFI_MEMORY_RUNTIME)) > + continue; > + if (!count--) > + break; > + iounmap((__force void *)md->virt_addr); > + } This is wrong. memmap still belongs to UEFI and hasn't been touched. The new mappings are in virtmap. So, it is even simpler: /* unmap all mappings that succeeded: there are 'count' of those */ for (virt_md = virtmap; count; virt_md++, count--) iounmap((__force void __iomem *)virt_md->virt_addr); > + kfree(virtmap); > + return -1; > } > early_initcall(arm64_enter_virtual_mode);
(adding Catalin) On 4 July 2014 16:42, Mark Salter <msalter@redhat.com> wrote: > On Fri, 2014-07-04 at 12:16 +0200, Ard Biesheuvel wrote: >> If we cannot resolve the virtual address of the UEFI System Table, its physical >> offset must be missing from the virtual memory map, and there is really no point >> in proceeding with installing the virtual memory map and the runtime services >> dispatch table. So back out gracefully. >> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> >> --- >> >> v2: >> - release mappings and free virtmap before bailing >> >> arch/arm64/kernel/efi.c | 28 ++++++++++++++++++++++++++-- >> 1 file changed, 26 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c >> index 56c3327bbf79..23942158e0f8 100644 >> --- a/arch/arm64/kernel/efi.c >> +++ b/arch/arm64/kernel/efi.c >> @@ -416,11 +416,23 @@ static int __init arm64_enter_virtual_mode(void) >> continue; >> if (remap_region(md, &virt_md)) >> ++count; >> + else >> + goto err_unmap; > > How about: > if (!remap_region(md, &virt_md)) > goto err_unmap; > ++count; > > Sure. >> } >> >> efi.systab = (__force void *)efi_lookup_mapped_addr(efi_system_table); >> - if (efi.systab) >> - set_bit(EFI_SYSTEM_TABLES, &efi.flags); >> + if (!efi.systab) { >> + /* >> + * If we have no virtual mapping for the System Table at this >> + * point, the memory map doesn't cover the physical offset where >> + * it resides. This means the System Table will be inaccessible >> + * to Runtime Services themselves once the virtual mapping is >> + * installed. >> + */ >> + pr_err("Failed to remap EFI System Table -- buggy firmware?\n"); >> + goto err_unmap; >> + } >> + set_bit(EFI_SYSTEM_TABLES, &efi.flags); >> >> local_irq_save(flags); >> cpu_switch_mm(idmap_pg_dir, &init_mm); >> @@ -453,5 +465,17 @@ static int __init arm64_enter_virtual_mode(void) >> set_bit(EFI_RUNTIME_SERVICES, &efi.flags); >> >> return 0; >> + >> +err_unmap: >> + /* unmap all mappings that succeeded: there are 'count' of those */ >> + for_each_efi_memory_desc(&memmap, md) { >> + if (!(md->attribute & EFI_MEMORY_RUNTIME)) >> + continue; >> + if (!count--) >> + break; >> + iounmap((__force void *)md->virt_addr); >> + } > > This is wrong. memmap still belongs to UEFI and hasn't been touched. The > new mappings are in virtmap. So, it is even simpler: > > /* unmap all mappings that succeeded: there are 'count' of those */ > for (virt_md = virtmap; count; virt_md++, count--) > iounmap((__force void __iomem *)virt_md->virt_addr); > Yes, you're right. Will respin.
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c index 56c3327bbf79..23942158e0f8 100644 --- a/arch/arm64/kernel/efi.c +++ b/arch/arm64/kernel/efi.c @@ -416,11 +416,23 @@ static int __init arm64_enter_virtual_mode(void) continue; if (remap_region(md, &virt_md)) ++count; + else + goto err_unmap; } efi.systab = (__force void *)efi_lookup_mapped_addr(efi_system_table); - if (efi.systab) - set_bit(EFI_SYSTEM_TABLES, &efi.flags); + if (!efi.systab) { + /* + * If we have no virtual mapping for the System Table at this + * point, the memory map doesn't cover the physical offset where + * it resides. This means the System Table will be inaccessible + * to Runtime Services themselves once the virtual mapping is + * installed. + */ + pr_err("Failed to remap EFI System Table -- buggy firmware?\n"); + goto err_unmap; + } + set_bit(EFI_SYSTEM_TABLES, &efi.flags); local_irq_save(flags); cpu_switch_mm(idmap_pg_dir, &init_mm); @@ -453,5 +465,17 @@ static int __init arm64_enter_virtual_mode(void) set_bit(EFI_RUNTIME_SERVICES, &efi.flags); return 0; + +err_unmap: + /* unmap all mappings that succeeded: there are 'count' of those */ + for_each_efi_memory_desc(&memmap, md) { + if (!(md->attribute & EFI_MEMORY_RUNTIME)) + continue; + if (!count--) + break; + iounmap((__force void *)md->virt_addr); + } + kfree(virtmap); + return -1; } early_initcall(arm64_enter_virtual_mode);
If we cannot resolve the virtual address of the UEFI System Table, its physical offset must be missing from the virtual memory map, and there is really no point in proceeding with installing the virtual memory map and the runtime services dispatch table. So back out gracefully. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- v2: - release mappings and free virtmap before bailing arch/arm64/kernel/efi.c | 28 ++++++++++++++++++++++++++-- 1 file changed, 26 insertions(+), 2 deletions(-)