fix/allsyms - #19593
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Arch: risc-v
g_allsyms/g_nallsyms only exist in the kernel image, but symtab_allsyms.c is unconditionally built into libc.a, so user-mode code under CONFIG_BUILD_PROTECTED/CONFIG_BUILD_KERNEL fails to link. Guard the affected code so user-mode libc.a no longer references these kernel-only symbols. Signed-off-by: liang.huang <liang.huang@houmo.ai> Assisted-by: Claude Code:claude-sonnet-5
allsyms_findbyvalue()/%pS printed a bogus name/offset for addresses outside the real symbol table's coverage, due to the boundary sentinels being matchable as real symbols. Compute the high sentinel from the actual symbol range and treat a sentinel match as "not found". Signed-off-by: liang.huang <liang.huang@houmo.ai> Assisted-by: Claude Code:claude-sonnet-5
allsyms_lookup() derived a symbol's size from the physically next table entry, assuming address order. Under CONFIG_SYMTAB_ORDEREDBYNAME the table is sorted by name instead, producing a huge bogus size in %pS/backtrace output. Scan for the closest larger address instead of relying on table order. Signed-off-by: liang.huang <liang.huang@houmo.ai> Assisted-by: Claude Code:claude-sonnet-5
Several risc-v assembly labels are .global but untyped, so mkallsyms.py (which only collects STT_FUNC symbols) silently drops them from the ALLSYMS table, and backtraces/%pS print raw addresses instead of names. Add .type <name>, function to the affected labels, matching existing convention elsewhere in the tree. Signed-off-by: liang.huang <liang.huang@houmo.ai> Assisted-by: Claude Code:claude-sonnet-5
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Summary
CONFIG_ALLSYMSdoesn't even link underCONFIG_BUILD_PROTECTED/CONFIG_BUILD_KERNEL:g_allsyms/g_nallsymsonly exist in the kernel image, butsymtab_allsyms.creferencing them is built into user-modelibc.atoo. Once that's fixed and you actually try backtraces, three more bugs show up: user-mode addresses get matched against unrelated kernel symbols, symbol sizes are garbage underCONFIG_SYMTAB_ORDEREDBYNAME, and a bunch of assembly-only entry points (exception/boot code) never resolve to a name because they were never markedSTT_FUNC. This PR fixes all four.Impact
Touches
libs/libc/symtab/symtab_allsyms.cand a few risc-v assembly boot/exception files. No new Kconfig, no API changes, nothing changes unlessCONFIG_ALLSYMS=y.Testing
All of the below is
rv-virt:knshwithCONFIG_ALLSYMS,CONFIG_SYSTEM_DUMPSTACK,CONFIG_FRAME_POINTER, andCONFIG_SCHED_BACKTRACEturned on by hand, unless noted otherwise. Also checked onpnsh, and regression-testednshto make sure nothing else broke.Problem 0: link failure under BUILD_PROTECTED/BUILD_KERNEL
rv-virt:knsh:rv-virt:pnsh, same underlying problem:Problems 1-3: after fixing the link error, boots but backtraces are wrong
Before fixing problems 1-3:
Three problems here:
register_blockdriver-style output), which is worse than useless.nxsem_wait_uninterruptible+0x16/0xffffb9b0.Unknown+0x8020004a/0x80207d2e).Problem 1 doesn't really have a fix beyond "don't lie": there's no way to resolve a user-mode symbol from kernel context, so the right behavior is just falling back to the raw address instead of guessing:
After fixing problem 2, symbol sizes are correct:
After fixing problem 3, assembly-only symbols resolve correctly too (
__start,exception_common):Known follow-up (not fixed here)
g_symtabandg_allsymshave nothing to do with each other — different data, different generators — butsymtab_findbyname()/symtab_findbyvalue()only get compiled once, so both tables end up forced to share the same global ordering assumption (CONFIG_SYMTAB_ORDEREDBYNAME/CONFIG_SYMTAB_ORDEREDBYVALUE).