| Message ID | 20250226132841.381063-1-xry111@xry111.site (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | MIPS: Ignore relocs against __ex_table for relocatable kernel | expand |
On Wed, 26 Feb 2025 21:28:41 +0800 Xi Ruoyao <xry111@xry111.site> wrote: > Since commit 6f2c2f93a190 ("scripts/sorttable: Remove unneeded > Elf_Rel"), sorttable no longer clears relocs against __ex_table, > claiming "it was never used." But in fact MIPS relocatable kernel had > been implicitly depending on this behavior, so after this commit the > MIPS relocatable kernel has started to spit oops like: Oops! > > CPU 1 Unable to handle kernel paging request at virtual address 000000fffbbdbff8, epc == ffffffff818f9a6c, ra == ffffffff813ad7d0 > ... ... > Call Trace: > [<ffffffff818f9a6c>] __raw_copy_from_user+0x48/0x2fc > [<ffffffff813ad7d0>] cp_statx+0x1a0/0x1e0 > [<ffffffff813ae528>] do_statx_fd+0xa8/0x118 > [<ffffffff813ae670>] sys_statx+0xd8/0xf8 > [<ffffffff81156cc8>] syscall_common+0x34/0x58 > > So ignore those relocs on our own to fix the issue. > > Fixes: 6f2c2f93a190 ("scripts/sorttable: Remove unneeded Elf_Rel") > Signed-off-by: Xi Ruoyao <xry111@xry111.site> Thanks! Yeah, this is better than having an implicit dependency to the sorttable code. I take it that this will go through the mips tree? -- Steve
On Wed, Feb 26, 2025 at 10:43:40AM -0500, Steven Rostedt wrote: > On Wed, 26 Feb 2025 21:28:41 +0800 > Xi Ruoyao <xry111@xry111.site> wrote: > > > Since commit 6f2c2f93a190 ("scripts/sorttable: Remove unneeded > > Elf_Rel"), sorttable no longer clears relocs against __ex_table, > > claiming "it was never used." But in fact MIPS relocatable kernel had > > been implicitly depending on this behavior, so after this commit the > > MIPS relocatable kernel has started to spit oops like: > > Oops! > > > > > CPU 1 Unable to handle kernel paging request at virtual address 000000fffbbdbff8, epc == ffffffff818f9a6c, ra == ffffffff813ad7d0 > > ... ... > > Call Trace: > > [<ffffffff818f9a6c>] __raw_copy_from_user+0x48/0x2fc > > [<ffffffff813ad7d0>] cp_statx+0x1a0/0x1e0 > > [<ffffffff813ae528>] do_statx_fd+0xa8/0x118 > > [<ffffffff813ae670>] sys_statx+0xd8/0xf8 > > [<ffffffff81156cc8>] syscall_common+0x34/0x58 > > > > So ignore those relocs on our own to fix the issue. > > > > Fixes: 6f2c2f93a190 ("scripts/sorttable: Remove unneeded Elf_Rel") > > Signed-off-by: Xi Ruoyao <xry111@xry111.site> > > Thanks! Yeah, this is better than having an implicit dependency to the > sorttable code. > > I take it that this will go through the mips tree? yes, I'll take it. Thomas.
On Wed, Feb 26, 2025 at 09:28:41PM +0800, Xi Ruoyao wrote: > Since commit 6f2c2f93a190 ("scripts/sorttable: Remove unneeded > Elf_Rel"), sorttable no longer clears relocs against __ex_table, > claiming "it was never used." But in fact MIPS relocatable kernel had > been implicitly depending on this behavior, so after this commit the > MIPS relocatable kernel has started to spit oops like: > > CPU 1 Unable to handle kernel paging request at virtual address 000000fffbbdbff8, epc == ffffffff818f9a6c, ra == ffffffff813ad7d0 > ... ... > Call Trace: > [<ffffffff818f9a6c>] __raw_copy_from_user+0x48/0x2fc > [<ffffffff813ad7d0>] cp_statx+0x1a0/0x1e0 > [<ffffffff813ae528>] do_statx_fd+0xa8/0x118 > [<ffffffff813ae670>] sys_statx+0xd8/0xf8 > [<ffffffff81156cc8>] syscall_common+0x34/0x58 > > So ignore those relocs on our own to fix the issue. > > Fixes: 6f2c2f93a190 ("scripts/sorttable: Remove unneeded Elf_Rel") > Signed-off-by: Xi Ruoyao <xry111@xry111.site> > --- > arch/mips/boot/tools/relocs.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/arch/mips/boot/tools/relocs.c b/arch/mips/boot/tools/relocs.c > index a88d66c46d7f..9863e1d5c62e 100644 > --- a/arch/mips/boot/tools/relocs.c > +++ b/arch/mips/boot/tools/relocs.c > @@ -468,6 +468,8 @@ static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel, > Elf_Sym *sym, const char *symname)) > { > int i; > + struct section *extab_sec = sec_lookup("__ex_table"); > + int extab_index = extab_sec ? extab_sec - secs : -1; > > /* Walk through the relocations */ > for (i = 0; i < ehdr.e_shnum; i++) { > @@ -480,6 +482,9 @@ static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel, > if (sec->shdr.sh_type != SHT_REL_TYPE) > continue; > > + if (sec->shdr.sh_info == extab_index) > + continue; > + > sec_symtab = sec->link; > sec_applies = &secs[sec->shdr.sh_info]; > if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) > -- > 2.48.1 applied to mips-fixes. Thomas.
diff --git a/arch/mips/boot/tools/relocs.c b/arch/mips/boot/tools/relocs.c index a88d66c46d7f..9863e1d5c62e 100644 --- a/arch/mips/boot/tools/relocs.c +++ b/arch/mips/boot/tools/relocs.c @@ -468,6 +468,8 @@ static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym, const char *symname)) { int i; + struct section *extab_sec = sec_lookup("__ex_table"); + int extab_index = extab_sec ? extab_sec - secs : -1; /* Walk through the relocations */ for (i = 0; i < ehdr.e_shnum; i++) { @@ -480,6 +482,9 @@ static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel, if (sec->shdr.sh_type != SHT_REL_TYPE) continue; + if (sec->shdr.sh_info == extab_index) + continue; + sec_symtab = sec->link; sec_applies = &secs[sec->shdr.sh_info]; if (!(sec_applies->shdr.sh_flags & SHF_ALLOC))
Since commit 6f2c2f93a190 ("scripts/sorttable: Remove unneeded Elf_Rel"), sorttable no longer clears relocs against __ex_table, claiming "it was never used." But in fact MIPS relocatable kernel had been implicitly depending on this behavior, so after this commit the MIPS relocatable kernel has started to spit oops like: CPU 1 Unable to handle kernel paging request at virtual address 000000fffbbdbff8, epc == ffffffff818f9a6c, ra == ffffffff813ad7d0 ... ... Call Trace: [<ffffffff818f9a6c>] __raw_copy_from_user+0x48/0x2fc [<ffffffff813ad7d0>] cp_statx+0x1a0/0x1e0 [<ffffffff813ae528>] do_statx_fd+0xa8/0x118 [<ffffffff813ae670>] sys_statx+0xd8/0xf8 [<ffffffff81156cc8>] syscall_common+0x34/0x58 So ignore those relocs on our own to fix the issue. Fixes: 6f2c2f93a190 ("scripts/sorttable: Remove unneeded Elf_Rel") Signed-off-by: Xi Ruoyao <xry111@xry111.site> --- arch/mips/boot/tools/relocs.c | 5 +++++ 1 file changed, 5 insertions(+)